Altered vasoactive intestinal peptides expression in irritable bowel syndrome patients and rats with trinitrobenzene sulfonic acid-induced colitis

AIM: To investigate the vasoactive intestinal peptides(VIP) expression in irritable bowel syndrome(IBS) and trinitrobenzene sulfonic acid(TNBS) induced colitis.METHODS: The VIP gene expression and protein plasma levels were measured in adult participants(45.8% male) who met Rome Ⅲ criteria for IBS for longer than 6 mo and in a rat model of colitis as induced by TNBS.Plasma and colons were collected from naive and inflamed rats.Markers assessing inflammation(i.e.,weight changes and myeloperoxidase levels) were assessed on days 2,7,14 and 28 and compared to controls.Visceral hypersensitivity of the rats was assessed with colo-rectal distension and mechanical threshold testing on hind paws.IBS patients(n = 12) were age,gender,race,and BMI-matched with healthy controls(n = 12).Peripheral whole blood and plasma from fasting participants was collected and VIP plasma levels were assayed using a VIP peptide-enzyme immunoassay.Human gene expression of VIP was analyzed using a custom PCR array.RESULTS: TNBS induced colitis in the rats was confirmed with weight loss(13.7 ± 3.2 g) and increased myeloperoxidase activity.Visceral hypersensitivity tocolo-rectal distension was increased in TNBS treated rats up to 21 d and resolved by day 28.Somatic hypersensitivity was also increased up to 14 d post TNBS induction of colitis.The expression of an inflammatory marker myeloperoxidase was significantly elevated in the intracellular granules of neutrophils in rat models following TNBS treatment compared to naive rats.This confirmed the induction of inflammation in rats following TNBS treatment.VIP plasma concentration was significantly increased in rats following TNBS treatment as compared to naive animals(P < 0.05).Likewise,the VIP gene expression from peripheral whole blood was significantly upregulated by 2.91-fold in IBS patients when compared to controls(P < 0.00001; 95%CI).VIP plasma protein was not significantly different when compared with controls(P = 0.193).CONCLUSION: Alterations in VIP expression may play a role in IBS.Therefore,a better understanding of the physiology of VIP could lead to new therapeutics.

Recombinant expressed vasoactive intestinal peptide analogue ameliorates TNBS-induced colitis in rats

AIM To investigate the modulatory effect of recombinantexpressed vasoactive intestinal peptide(VIP) analogue(rVIPa) on trinitrobenzene sulfonic acid(TNBS)-induced colitis in rats. METHODS Forty-eight rats were randomized into six groups: normal control group(Control), model control group(TNBS), ethanol treatment group(ETOH), and VIP treatment groups with different dosage(rVIPa_(1nmol), rVIPa_(2nmol), rVIPa_(4nmol)). Diarrhea and bloody stool were observed. Colonic damage was evaluated histologically. The levels of tumor necrosis factor-α( TNF-α), interleukin-10(Il-10), myeloperoxidase(MPO) and endotoxin in colonic tissue and serum were determined by enzyme-linked immunosorbent assay(ElISA). The expression of occludin, ZO-1, Toll-like receptor 4(TlR4),and nuclear factor-kappa B p65(NF-κBp65), IκBα, and p-IκBα were detected by Western blot. RESULTS Administration with 2 nmol rVIPa prevented TNBSinduced necrosis, hyperemia, swelling, inflammation, etc., pathologic changes observed in the inner surface of colon in experimental rats. Moreover, rVIPa significantly decreased colonic TNF-α level(P < 0.001), MPO activity(P < 0.001) and serum endotoxin level(P < 0.01), and remarkably increased colonic Il-10 content(P < 0.001) in rats with TNBS-induced colitis. Furthermore, compared to the TNBS-induced colitis group, 2 nmol rVIPa treatment up-regulated the levels of occludin(P < 0.05) and ZO-1(P < 0.05), NF-κB p65(P < 0.01) and IκBα(P < 0.001), and down-regulated the levels of TlR4. CONCLUSION rVIPa ameliorates TNBS-induced colonic injury and inflammation and effectively protected the intestinal mucosal barrier function in rats. The mechanism may be related to TlR4/NF-κB-mediated signaling pathway. rVIPa could be used as a new alternative therapy for intestinal inflammatory disorders.

Differences and significance of motilin,vasoactive intestinal peptide and gastrin in blood and gallbladder tissues of patients with gallstones

BACKGROUND: The disorders of gallbladder motility may play an important role in the formation of gallstones. Many neural and hormonal factors and their interactions regulate gallbladder motility and bile flow into the duodenum. Further study in these factors may help to reveal the etiology of gallbladder diseases. This study was undertaken to assess the relationship of the levels of motilin, vasoactive intestinal peptide (VIP) and gastrin in blood and gallbladder tissues with the formation of cholelithiasis. METHODS: The levels of motilin, gastrin and VIP in blood and gallbladder tissues of 36 patients with gallbladder stones, 14 patients with gallbladder polyps, 10 healthy volunteers and 10 patients with common bile duct stones were measured by radioimmunoassay. RESULTS: The level of motilin in plasma and gallbladder tissues of the gallbladder stone group was higher than that of the control and gallbladder polyp groups (P<0.05). The levels of plasma VIP and serum gastrin were much higher than those of the other three groups (P<0.01). The level of VIP in gallbladder tissues was higher than that of the control and gallbladder polyp groups (P<0.01). CONCLUSIONS: The abnormal excretion of hormonal factors is closely related to gallstone formation. The high level of VIP in gallbladder tissues may be an important cause of gallbladder hypomotility. The abnormal level of serum gastrin may be related to the gastrointestinal symptoms of patients with gallstones.

Role of vasoactive intestinal peptide and nitric oxide in the modulation of electroacupucture on gastric motility in stressed rats

AIM: To investigate the effects and mechanisms of vasoactive intestinal peptide (VIP) and nitric oxide (NO) in the modulation of electroacupucture (EA) on gastric motility in restrained-cold stressed rats. METHODS: An animal model of gastric motility disorder was established by restrained-cold stress. Gastric myoelectric activities were recorded by electrogastroent erography (EGG). VIP and NO concentrations in plasma and gastric mucosal and bulb tissues were detected by radioimmunoassay (RIA). VIP expression in the gastric walls was assayed using avidin-biotin-peroxidase complex (ABC) and image analysis. RESULTS: In cold restrained stressed rats, EGG was disordered and irregular. The frequency and amplitude of gastric motility were higher than that in control group (P < 0.01). VIP and NO contents of plasma, gastric mucosal and bulb tissues were obviously decreased (P < 0.01). Following EA at “Zusanli” (ST36), the frequency and amplitude of gastric motility were obviously lowered (P < 0.01), while the levels of VIP and NO in plasma, gastric mucosal and bulb tissues increased strikingly (P < 0.01, P < 0.05) and expression of VIP in antral smooth muscle was elevated significantly (P < 0.01) in comparison with those of model group. CONCLUSION: VIP and NO participate in the modulatory effect of EA on gastric motility. EA at “Zusanli” acupoint (ST36) can improve gastric motility of the stressed rats by increasing the levels of VIP and NO.

Effects of psychological stress on small intestinal motility and expression of cholecystokinin and vasoactive intestinal polypeptide in plasma and small intestine in mice

AIM: To investigate the effects of psychological stress on small intestinal motility and expression of cholecystokinin (CCK) and vasoactive intestinal polypeptide (VIP) in plasma and small intestine, and to explore the relationship between small intestinal motor disorders and gastrointestinal hormones under psychological stress. METHODS: Thirty-six mice were randomly divided into psychological stress group and control group. A mouse model with psychological stress was established by housing the mice with a hungry cat in separate layers of a two-layer cage. A semi-solid colored marker (carbon-ink) was used for monitoring small intestinal transit. CCK and VIP levels in plasma and small intestine in mice were measured by radioimmunoassay (RIA). RESULTS: Small intestinal transit was inhibited (52.18±19.15% vs70.19±17.79%, P<0.01) in mice after psychological stress, compared to the controls. Small intestinal CCK levels in psychological stress mice were significantly lower than those in the control group (0.75±0.53 μg/g vs1.98±1.17 μg/g, P<0.01), whereas plasma CCK concentrations were not different between the groups. VIP levels in small intestine were significantly higher in psychological stress mice than those in the control group (8.45±1.09 μg/g vs7.03±2.36 μg/g, P<0.01), while there was no significant difference in plasma VIP levels between the two groups. CONCLUSION: Psychological stress inhibits the small intestinal transit, probably by down-regulating CCK and up-regulating VIP expression in small intestine.

Vasoactive intestinal peptide,a promising agent for myopia?

AIM： To investigate the role of vasoactive intestinal peptide（VIP） in form-deprivation myopia（FDM）.METHODS： FDM was created in three groups of eight chicks by placing a translucent diffuser on their right eyes.Intravitreal injections of saline and VIP were applied once a day into the occluded eyes of groups 2 and 3,respectively.Retinoscopy and axial length（AL） measurements were performed on the first and 8^th days of diffuser wear.The retina mR NA levels of the VIP receptors and the ZENK protein in right eyes of the three groups and left eyes of the first group on day 8 were determined using real time polymerase chain reaction（PCR）.RESULTS： The median final refraction（D） in right eyes were-13.75（-16.00,-12.00）,-11.50（-12.50,-7.50）,and-1.50（-4.75,-0.75） in groups 1,2,and 3,respectively（P〈0.001）.The median AL（mm） in right eyes were 10.65（10.00,11.10）,9.90（9.70,10.00）,and 9.20（9.15,9.25） in groups 1,2,and 3,respectively（P〈0.001）.The median delta-delta cycle threshold（CT） values for the VIP2 receptors were 1.07（0.82,1.43）,1.22（0.98,1.65）,0.29（0.22,0.45） in right eyes of groups 1,2,and 3,and 1.18（0.90,1.37） in left eyes of group 1,respectively（P=0.001）.The median delta-delta CT values for the ZENK protein were 1.07（0.63,5.03）,3.55（2.20,5.55）,undetectable in right eyes of groups 1,2,and 3 and 1.89（0.21,4.73） in left eyes of group 1,respectively（P=0.001）.CONCLUSION： VIP has potential inhibitory effects in the development of FDM.

Roles of sphincter of Oddi motility and serum vasoactive intestinal peptide,gastrin and cholecystokinin octapeptide

AIM: To investigate roles of sphincter of Oddi (SO) motility played in pigment gallbladder stone formation in model of guinea pigs.

Research advances of vasoactive intestinal peptide in the pathogenesis of ulcerative colitis by regulating interleukin-10 expression in regulatory B cells

Ulcerative colitis(UC)is a chronic relapsed intestinal disease with an increasing incidence around the world.The pathophysiology of UC remains unclear.However,the role of the interaction between the enteric nervous system and the immune system in the pathogenesis of UC has been the focus of attention and has become a research hotspot.Vasoactive intestinal peptide(VIP)is a kind of endogenous neuropeptide with regulatory activity on intestinal immunity.It has been shown to regulate immune disorders in animal and human experiments and has become an effective anti-inflammatory and immune modulator that affects the innate immune system and adaptive immune system.Regulatory B cells(Bregs)are a new group of B cells that negatively regulate the immunity and have received extensive attention in immune circles.Bregs can regulate immune tolerance by producing interleukin(IL)-10,IL-35,and transforming growth factor-β,suppressing autoimmune diseases or excessive inflammatory responses.The secretion of IL-10 by Bregs induces the development of T helper(Th)0 and Th2 cells.It also induces Th2 cytokines and inhibits Th1 cytokines,thereby inhibiting Th1 cells and the Th1/Th2 balance.With further clarity on the mechanism of the regulation of IL-10 expression by VIP in Bregs in colitis patients,we believe that Bregs can provide a novel strategy for the clinical treatment of UC.Thus,we aim to review the current literature on this evolving topic.

Effect of fluoxetine on depression-induced changes in the expression of vasoactive intestinal polypeptide and corticotrophin releasing factor in rat duodenum

AIM: To investigate changes in vasoactive intestinal polypeptide (VIP) and corticotrophin releasing factor (CRF) in the plasma and duodenum of chronic stress- induced depressed rats and the effects of fluoxetine hydrochloride (fluoxetine) treatment on depression- induced changes in VIP and CRF. METHODS: A Sprague-Dawley rat model of chronic stress-induced depression was produced. Thirty experimental rats were randomly divided into the following groups: control group, saline-treated depressed group, and fluoxetine-treated depressed group. Open- f ield testing was performed to assess the rats’ behavior. VIP and CRF levels in plasma were measured by ELISA. Immunofluorescence techniques combined with laser scanning confocal microscopy (LSCM) were used to investigate VIP and CRF expression in the duodenum. RESULTS: The open-field behavior, both crossing and rearing, of depression model rats, decreased signif icantly compared with those of normal control rats over 5 min. Defecation times increased significantly. Compared to the control group, FITC fluorescence of duodenal CRF expression and plasma CRF levels in the depressed rats increased significantly (fluorescence intensity of duodenal CRF: 11.82 ± 2.54 vs 25.17 ± 4.63; plasma CRF: 11.82 ± 2.54 ng/L vs 25.17 ± 4.63 ng/L, P < 0.01), whereas duodenal VIP expression and plasma VIP levels decreased signif icantly (fluorescence intensity of duodenal VIP: 67.37 ± 18.90 vs 44.51 ± 16.37; plasmaVIP: 67.37 ± 18.90 ng/L vs 44.51 ± 16.37 ng/L, P < 0.01). Fluoxetine improved depressed behavior, increased VIP expression and decreased CRF expression in plasma and the duodenal tissue of depressed rats. CONCLUSION: Chronic stress can induce injury to the duodenum, accompanied by increasing CRF and decreasing VIP in the plasma and duodenum. Treatment with fluoxetine can ameliorate pathological changes in the duodenum of depressed rats, which suggests that antidepressants are an effective therapeutic agent for some duodenal diseases caused by chronic stress. VIP is a potential therapeutic strategy.

Effect of vasoactive intestinal peptide on the wound healing of alkali-burned corneas

AIM： To study the effect of vasoactive intestinal peptide （VIP） on wound healing in experimental alkali burns of the cornea. METHODS： Twenty-seven albino rabbits, weighing 3.2 -0.75 kg were used. Alkali burns were induced on corneas by applying 10 mm Whatman paper No：50 soaked in 1 mol/L NaOH. They have further classified into 5 groups as follows： 1） control group given no treatment （n=5）; 2） VIP given subconjunctivally （n=6）; 3） VIP injected into anterior chamber （n=6）; 4） NaCI 0.9% given subconjunctivally （n=5）; 5） NaCI 0.9% given into the anterior chamber （n=5）. All treatment protocols except control group were followed by topical eye drops composed of VIP at two hourly intervals for one week from 8 a.mo to 6 p.m, RESULTS： VIP treated groups of rabbits with alkali burns were found to have better wound healing findings histo-pathologically when compared to those of control group who have received no treatment on day 30. No differences were observed between groups in respect to degree of polymorphonuclear leukocytes （PMNL） infiltration and degree of loss of amorphous substrate on day 15. However, PMNL infiltration and degree of loss of amorphous substrate were lower in Groups 2 and 3 when compared to that of control group on day 30 （P〈0.05）. CONCLUSION： We have shown that VIP has positive effects on alkali induced corneal burns. VIP may inhibit PMNL migration to cornea through an immunomodulatory effect. Inhibition of PMNL migration might reduce the release of collagenaees and this might prevent the extracellular amorphous substance loss.

Vasoactive Intestinal Peptide (VIP) and VIP Receptors-Elucidation of Structure and Function for Therapeutic Applications

Vasoactive intestinal peptide (VIP) is a 28-amino acid polypeptide first isolated from swine duodenum. VIP is a neurotransmitter that is extensively distributed in tissues. According to published reports, VPAC1 and VPAC2 act as VIP receptors and are widely present in the central nervous system and peripheral tissues. VIP exerts diverse actions on the cardiovascular system, pancreas, digestive tract, respiratory system, and urological system. Recent reports indicated that VIP has immunological and neuroprotective effects and also affects cell growth. While primary investigations for developing therapeutic applications for various pathological conditions and diseases are underway, the structure and function of VIP should be analyzed in more detail.

Role of vasoactive intestinal peptide in Aspergillus fumigatus-infected cornea

AIM： To investigate the anti-inflammatory role of vasoactive intestinal peptide（VIP） in Aspergillus fumigatus（A. fumigatus） ketatitis.METHODS： Expression of VIP was tested by polymerase chain reaction（PCR） in C57BL/6 and BALB/c normal and A. fumigatus infected corneas. C57BL/6 mice were pretreated with recombinant（r） VIP, while BALB/c mice were pretreated with VIP antagonist, and then infected with A. fumigatus. Clinical score was recorded. Expression of pro-and anti-inflammatory cytokines, toll-like receptor 4（TLR4）, lectin-like oxidized low-density lipoprotein receptor 1（LOX-1）, and neutrophil infiltration were tested by PCR, enzyme-linked immunosorbent assay（ELISA）, and myeloperoxidase（MPO） assay.RESULTS： VIP mR NA expression in BALB/c cornea was higher than C57BL/6 cornea at 1 and 3 d post infection（p.i.）. rV IP treatment of C57BL/6 mice showed alleviated disease and down-regulated expression of interleukin-1β（IL-1β） and tumor necrosis factor-α（TNF-α）, while IL-10 expression was up-regulated. Neutrophil infiltration and TLR4, IL-17 expression were decreased after rVIP treatment, while LOX-1 expression was up-regulated in C57BL/6. VIP antagonist pretreatment showed increased disease and higher IL-1β, TNF-α, TLR4, IL-17 and MPO levels, while IL-10 and LOX-1 levels were down-regulated in BALB/c mice.CONCLUSION： rVIP alleviate disease response of C57BL/6 mice. VIP antagonist resulted in worsened disease of BALB/c mice. VIP proposed anti-inflammatory role in A. fumigatus keratitis.

Octreotide reverses shock due to vasoactive intestinal peptide-secreting adrenal pheochromocytoma: A case report and review of literature

Vasoactive intestinal peptide-producing tumors （VIP-oma） usually originate in the pancreas and are chara-cterized by diarrhea, hypokalemia, and achlorhydria （WDHA syndrome）. In adults, nonpancreatic VIPoma is very rare. Herein, we report an unusual case of VIP-producing pheochromocytoma marked by persistent shock, fushing, and watery diarrhea and high sensitivity to octreotide. A 53-year-old woman was hospitalized for sudden-onset hypertension with convulsions, which then rapidly evolved to persistent shock, fushing, and watery diarrhea. Abdominal computed tomography indicated a left adrenal mass, accompanied by bleeding;and marked elevations of both plasma catecholamine and VIP concentrations were documented via laboratory testing. Surprisingly, all clinical symptoms responded swiftly to octreotide treatment. Once surgically treated, hormonal levels normalized in this patient, and the clinical symptoms dissipated. Postoperative pathological and immunohistopathological studies confrmed a VIP-secreting pheochromocytoma with strong, diffuse positivity for somatostatin receptor type 2. During a 6-mo follow-up period, she seemed in good health andwas symptom-free.

Vasoactive intestinal polypeptide (VIP) corrects chronic inflammatory response syndrome (CIRS) acquired following exposure to water-damaged buildings

Exposure in water-damaged buildings (WDB) to airborne bioaerosols including metabolic products of toxigenic fungi, bacteria and actinomycetes;and inflammagens, can lead to a persistent innate immune inflammatory illness. This illness, termed a chronic inflammatory response syndrome (CIRS-WDB), is systemic with symptoms acquired from multiple organ systems. Treatment of CIRS-WDB has progressed rapidly as a better understanding of the inflammatory pathophysiology has led to targeted, sequential therapies. The fundamental basis of uncontrolled innate immune responses, the humoral deficiency of regulatory neuropeptides melanocyte stimulating hormone (MSH) or vasoactive intestinal polypeptide (VIP), seen in over 98% of pa tients, has not consistently responded to any treatment modality. Use of replacement VIP has been attempted anecdotally;VIP replacement therapies show promise in short term studies but longer therapies have not been attempted. Here we report an open label trial of 20 patients with refractory CIRS-WDB illness who took replacement VIP in a nasal spray for at least 18 months with confirmation of durable efficacy and absence of significant side effects. These 20 patients were similar in symptoms and lab find- ings to three previously published cohorts in- volving 1829 patients and 169 controls. Dosage of VIP was titrated downwards from four to zero doses a day to determine minimum effective dose, and retitrated upwards for maximum improvement over time. The trial showed that VIP therapy safely 1) reduced refractory symptoms to equal controls;2) corrected inflammatory parameters C4a, TGF beta-1, VEGF, MMP9;3) corrected estradiol, testosterone and 25-OH Vitamin D;4) returned pulmonary artery systolic pressure (PASP) during exercise to normal;and 5) enhanced quality of life in 100% of trial patients. Subsequent identification of correction of T-regulatory cell levels supports the potential role of VIP in both innate and adaptive immune function.

Vasoactive intestinal peptide secreting tumour:An overview

Vasoactive intestinal peptide(VIP)secreting tumour(VIPoma)is a rare functional neuroendocrine tumour that typically arises from pancreatic islet cells.These present as sporadic,solitary pancreatic neoplasias with an estimated incidence of one in ten million individuals per year.Only around 5%of VIPomas are associated with multiple endocrine neoplasia type I syndrome.Excessive VIP secretion produces a clinical syndrome characterized by refractory watery diarrhoea,hypokalemia and metabolic acidosis.These coupled with elevated plasma levels of VIP are diagnostic.The majority of VIPomas are malignant and have already metastasized at the time of diagnosis(60%).Metastases occur most frequently in the liver,or regional lymph nodes,lungs,kidneys and bones.Some reports of skin metastases have been documented.Complete surgical resection continues to be the only potentially curative treatment.However,when the neoplasia cannot be excised completely,surgical debulking may provide palliative benefit.Other palliative options have included recently the peptide receptor radionuclide therapy which has shown to be effective and well-tolerated.This article will review all aspects of pancreatic VIPomas highlighting aspects such as clinical presentation,diagnosis and management.

Effect of vasoactive intestinal peptide on proliferation of hepatoma cells

It has been found that vasoactive intestinal peptide (VIP) stimulates the growth ofseveral kinds of tumor cells.There is no report so far about the effect of VIP on the growth ofhepatoma cells.Using the tetrazolium colorimetric assay (MTT assay) and cell countingmethod,it was investigated that the effect of VIP on the growth of a cultured rat hepatomaFSK-7902 cells.The results showed that VIP stimulated the proliferation of the rat hepatomacells obviously.The addition of 1μmol/L VIP caused a significant increase in the number of thecultured rat hepatoma cells on 3rd day and maximal increase occured on 4th day and 5th day ( P【0.01).The growth promoting effect was greater as the concentration of VIP increased.Thelowest effective concentration of VIP was 0.5μmol/L.Exposure to VIP for 12 h followed by re-moval of the peptide resulted in sustained growth for several days.

Study on vasoactive intestinal polypeptide receptor 1 gene translation in psoriatic epidermis with the topical treatment of capsaicin ointment

Objective To investigate the mechanism of capsaicin in treating active psoriasis vulgaris.Methods A total of 42 patients with active psoriasis vulgaris diagnosed by histology and clinical features were given either placebo or 0.025% capsaicin ointment four times daily for 30 days randomly by double-blind method.Vasoactive intestinal polypeptide receptor 1(VIPR1)gene translation in active psoriatic lesions before and after treatment with capsaicin ointment was detected by in situ hybridization.Results There was positive staining of VIPR1 gene in all the layers of psoriatic epidermis(95.5%)before the treatment with capsaicin ointment,but nearly no dyeing in epidermis(18.2%)after the treatment for 30 days.There was nearly no brown staining before and after treatment in control group.Conclusion VIPR1 gene translation in psoriatic epidermis is down-regulated after capsaicin treatment for 30 days.

EFFECTSOFVASOACTIVEINTESTINALPEPTIDEONACTIVITIESOFSUCCINICDEHYDROGENASEANDALKALINEPHOSPHATASEINRATHEPATOMACELLS

Using cytochemical method,microspectrophotometry and image analysis,effects of va-soactive intestinal peptide(VIP)on activities of succinic dehydrogenase(SDH)and alkalinephosphatase(ALP)in rat hepatoma cells were studied in vitro.The results showed that thehepatoma cell expressed potent positive reactions of SDH and ALP,the positive positionswere located at the cell membranes and/or cytoplasm.Having been treated with VIP,ALPdecreased obviously in activity(P【0. 01,compared with hepatoma cells untreated by VIP).The sites of ALP activty were chiefly located at the cell membranes,particularly at the cell-cell contacts.Cultured rat hepatoma cells had intensive SDH activity in their cytoplasm.Compared with untreated eclls,there was no marked difference in the intensity of SDH activ-ity in VIP-treated hepatoma cells(P】0.05).

VASOACTIVE INTESTINAL POLYPEPTIDE PREVENTS INJURY OF PULMONARY VASCULAR PERMEABILITY DUE TO XANTHINE WITH XANTHINE OXIDASE

Hyperpermeability is a crux of pathogenesis of sudden lung edema in many pulmonary disorders. especially in acute lung injury and adult respiratory distress syndrome(ARDS). Using our modified method for assessment of pulmonary vascular permeability. we observed the effects of xanthine with xanthine oxidase(X-XO) perfused in rat pulmonary artery and the protection of vasoactive intestinal polypeptide(VIP) against the injury of pulmonary vascular permeabilrty. After addition of xanthine oxidase in the perfusate reservoir containing xanthine￣(125) I-albumin leak index (￣(125)IALI)was remarkably increased while peak airway pressure(Paw) was not significantly increased, and perfusion pressure of pulmonary artery(Ppa)and lung wet/dry weight ratio(W/D) were only slightly increased. Xanthine plus xanthine oxidase also increased thromboxane B_2(TX B_2) and 6-keto-prostaglandin F_(1α)(6-keto -PGF_(1α)) in the perfusate. Treatment with VIP obviously reduced or totally prevented all signs of injury. Simultaneously, VIP also diminished or abolished the associated generation of arachidonate products. The results indicated that VIP has potent protective activity against injury of pulmonary vascular permeability and may be a physiological modulator of inflammatory damage to vascular endothelium associated with toxic oxygen metacolites.

RELAXANT EFFECTS OF VASOACTIVE INTESTINAL PEPTIDE ON PULMONARY ARTERY IN CHRONICALLY HYPOXIC RATS

The object of this study is to investigate the effect of VIP on pulmonary artery of chronically hypoxic rats. It was shown that chronic hypoxia depressed significantly pulmonary artery relaxation induced by VIP as compared with those of control (P<0. 001). The vascular relaxation of both groups was correlated with concentration of VIP. In addition, the relaxant effect of VIP on pulmonary arteries in rats was endothelium─independent, and was not prevented by indomethacin or nordihydroguaiaretic acid, but was abolished completely by methylene blue. These results suggest that the lower relaxation of pulmonary artery in rats might not be due to the endothelial injury caused by chronic hypoxia, and chronic hypoxia may inhibit directly the soluble guanylate cyclase in vascular smooth muscle cells invloved in synthesis of cGMP and thus reduced the sensitivity and reactivity of pulmonary artery to VIP.