Nano Lanthanum Oxide Preparation by Alkalescent Ammonium Citrate System and Its Primary Biological Effect

Using alkalescent ammonium(AAC)as precipitatnt, the diameter of nano La_2O_3 powder with diameter in 80 nm and less was prepared by the method of homogeneous precipitation, and reactant concentration, temperature and pH were studied and confirmed. The best precipitated concentration is from 0.2 to 0.5 mol·L^(-1), and the diameter of compounded powder turns small as the temperature gradually becomes high, and the pH from 6 to 8 is the best and the concentration of precipitant does not affect the diameter of compounded powder significantly. Meanwhile, most experiments lasting for fifty days in the greenhouse, and the results are 0.2 g·kg^(-1) nano La_2O_3 powder is enorgh for increasing biomass by 133% compared with that of the CK.

The Citrate Metabolism in Homo-and Heterofermentative LAB:A Selective Means of Becoming Dominant over Other Microorganisms in Complex Ecosystems

The citrate metabolism has been extensively studied in lactic acid bacteria (LAB) for its aroma compound production. Among the 4-carbon (C4) by-products obtained from citrate fermentation, diacetyl is one of the better known products for its contribution to the buttery aroma of dairy products. A lot of documents deal with ways to improve diacetyl concentration in food matrices. Apart from these organoleptic advantages, in a microbial ecosystem, the citrate metabolism gives selective advantages to citrate positive microorganisms. Citrate metabolism allows the LAB to use another carbon source for their growth, withstand acidic conditions and generate a “proton motive force” (PMF). Moreover, the citrate/glucid co-metabolism leads to the fast release of organic compounds known for having bacteriostatic effects. Under specific conditions, the C4?pathway liberates diacetyl which is bacteriostatic. In this review we first describe the citrate metabolism and the enzymes involved in the two homo- and heterofermentative LABLc diacetylactisandLeuconostocspp. Moreover, the way to shift the metabolic pathway toward the production of aromatic compounds is discussed for both of these fermentative types of bacteria. Finally, the selective advantages of citrate metabolism for LAB in complex microbial ecosystems are delineated.

Phosphotungstic acid immobilized on amino-functionalized TS-1 zeolite as a solid acid catalyst for the synthesis of tributyl citrate

The amino-functionalization of TS-1 zeolite followed by immobilization of phosphotungstic acid(HPW)was presented to prepare a strong solid acid catalyst for the synthesis of bio-based tributyl citrate from the esterification of citric acid and n-butanol.γ-Aminopropyltriethoxysilane(APTES)was first grafted on the TS-1 zeolite via the condensation reactions with surface hydroxyl groups,and subsequently the HPW was immobilized via the reaction between the amino groups and the protons from HPW-forming strong ionic bonding.The Keggin structure of HPW and MFI topology of TS-1 zeolite were well maintained after the modifications.The amino-functionalization generated abundant uniformly distributed active sites on TS-1 for HPW immobilization,which promoted the dispersity,abundance,as well as the stability of the acid sites.The tetrahedrally coordinated framework titanium and non-framework titania behaved as weak Lewis acid sites,and the protons from the immobilized HPW acted as the moderate or strong Brønsted acid sites.An optimized TBC yield of 96.2%(mol)with a conversion of-COOH of 98.1%(mol)was achieved at 150℃for 6 h over the HPW immobilized on amino-functionalized TS-1.The catalyst exhibited good stability after four consecutive reaction runs,where the activity leveled off at still a relatively high level after somewhat deactivation possibly caused by the leaching of a small portion of weakly anchored APTES or HPW.

Usefulness of Newly Devised Clomiphene Citrate Administration Method Compared with the Conventional Method in Ovulation and Pregnancy

Objective: Since not all women wish to conceive a child through aggressive treatment, we investigated the usefulness of modified repeated intracyclic clomiphene citrate (CC) therapy (repeated CC therapy) as a newly devised administration method. Methods: We evaluated the effects of CC administration on menstrual cycle length and retrospectively compared ovulation and pregnancy in 220 women who received CC at our hospital. Patients in the conventional method group received 50 mg per day for five days, starting on the fifth day of menstruation (withdrawal bleeding). Groups with and without menstrual cycle shortening after conventional CC administration were compared. The repeated CC therapy group was also compared with the non-shortened group. Repeated CC therapy was administered for the first five days as in the conventional method, and a second five-day repeat treatment was administered after an interval of five to seven days. Pregnancy rates, including indirect pregnancies, were evaluated by three different methods. Results: Ovulation and pregnancy rates were significantly better in the shortened group than in the non-shortened group (P < 0.001 and P = 0.010, respectively). Even in the non-shortened group, ovulation and pregnancy rates including indirect pregnancies were significantly improved when ovulation was observed with repeated CC therapy (P < 0.001 and P = 0.022, respectively). Conclusions: For patients whose menstrual cycle was not improved or shortened, repeated CC therapy as the newly devised CC administration method is useful as the next step after the conventional CC administration method.

Analysis of the Effect of High-Dose Segmental Citrate Anticoagulation in High Flux Hemodialysis

Objective:To analyze the clinical effect of high-dose citrate in segmental extracorporeal anticoagulation for high-throughput hemodialysis.Methods:The subjects included in this study were admitted to the hospital for maintenance hemodialysis treatment from January 2021 to January 2023.All patients had a high risk of bleeding and received 4%trisodium citrate anticoagulant treatment,administered at a rate of 200 mL/h before and after the dialyzer.The anticoagulant effects achieved by the patients were observed and analyzed.Results:The total number of patients who received high-dose segmented citrate extracorporeal anticoagulation dialysis treatment was 50,with each patient undergoing 100 treatments.During the treatment,2 patients had to end the treatment early due to transmembrane pressure exceeding 30 mmHg and an increase in venous pressure exceeding 250 mmHg;the treatment times for these patients were 20 minutes and 200 minutes,respectively.The remaining patients successfully completed the 4-hour treatment.Blood pH and calcium ion concentration in the venous pot were monitored.It was observed that before dialysis,after 2 hours of dialysis,and at the end of dialysis,the blood pH of the patients remained within a relatively normal range.Although some patient levels changed after dialysis,they remained within the normal range.No adverse reactions(such as numbness of the limbs or convulsions)were observed during the anticoagulant treatment.Conclusion:Administering 4%trisodium citrate at a rate of 200 mL/h before and after the dialyzer achieves a good anticoagulant effect,maintains the patient’s blood gas levels within the normal range at the end of dialysis,and causes no adverse reactions.

Preparation of high active Pt/C cathode electrocatalyst for direct methanol fuel cell by citrate-stabilized method

Platinum nanoparticles supported on carbons（Pt/C,60%,mass fraction） electrocatalysts for direct methanol fuel cell（DMFC） were prepared by citrate-stabilized method with different reductants and carbon supports.The catalysts were characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM） and cyclic voltammetry（CV）.It is found that the size of Pt nanoparticles on carbon is controllable by citrate addition and reductant optimization,and the form of carbon support has a great influence on electrocatalytic activity of catalysts.The citrate-stabilized Pt nanoparticles supported on BP2000 carbon,which was reduced by formaldehyde,exhibit the best performance with about 2 nm in diameter and 66.46 m2/g（Pt） in electrocatalytic active surface（EAS） area.Test on single DMFC with 60%（mass fraction） Pt/BP2000 as cathode electrocatalyst showed maximum power density at 78.8 mW/cm2.

Electrochemical reduction process of Co(Ⅱ) in citrate solution

Effects of citrate concentration and pH on the electrochemical reduction process of Co（Ⅱ） were investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. The results show that Co（Ⅱ） is reduced into two species which are free Co2＋ and [Co（C6H607）] in the solution composed of 0.05 mol/L CoS04·5H2O, 0.20 mol/L Na2SO4 and 0-0.40 mol/L C6H5O7Na3·2H2O in the pH range of 3-9. The reduction behavior depends on the pH of the solution. Co（H） is mainly reduced into the form of free Co^2＋ at pH 3 and into the form of [Co（C6H6O7）] at the pH range of 4-6 in citrate solution. The [Co（C6H6O7）] is first reduced to an intermediate state and then to Co°. Adsorption of the intermediate state exists on the surface of the electrode. Co（Ⅱ） is difficult to be reduced in the solution with the pH above 7, because the existing Co（Ⅱ）-citrate complex species [Co（C6H5O7）]- and [Co（C6H4O7）]2- are more difficult to be reduced than the hydrogen ion.

Mechanism of action of Linggui Zhugan Decoction in treating non-alcoholic fatty liver disease using untargeted metabolomics approach

Background:Non-alcoholic fatty liver disease(NAFLD)is a liver disorder characterized by the accumulation and degeneration of fat in the liver cells,a condition that may further deteriorate and lead to cirrhosis and liver cancer.Numerous studies showed that metabolic dysfunction can promote NAFLD development.Linggui Zhugan Decoction(LGZGD)has therapeutic effects on NAFLD.The mechanism of LGZGD still remains unclear.This study was to examine the impact of LGZGD on the metabolic processes involved in the development of NAFLD.Methods:A mice model of NAFLD was treated with LGZGD.The therapeutic potential of LGZGD was evaluated by assessing the activity of transaminases,lipids levels of blood,and pathological changes in the liver of the mice model of NAFLD.Additionally,this study also evaluated the influence of LGZGD on liver inflammation and oxidative stress.Results:The results of untargeted metabolomics analysis showed that LGZGD reduced the disordered lipid metabolism in NAFLD mice.LGZGD improved the oxidative stress and also reduced the levels of pro-inflammatory cytokines in the liver.Untargeted metabolomics analysis of liver samples revealed that LGZGD treatment improved metabolic disorders,including alanine,aspartate,glutamate,glycerophospholipid metabolism,and citrate cycle.Further RT-qPCR and Western blot results showed that LGZGD could regulate the expression of key enzymes in the metabolic pathway of the citrate cycle,including ATP-citrate lyase(ACLY),alanine-glyoxylate aminotransferase-2(AGXT2),phosphatidylethanolamine N-methyltransferase(PEMT),and succinate dehydrogenase(SDH).Conclusion:We found that LGZGD can treat NAFLD by reducing inflammatory responses,inhibiting oxidative stress,regulating alanine,aspartate,glutamate,and glycerophospholipid metabolism,and citrate cycle pathways.

几种常用的核染色标记物pH 6.0 Citrate和pH 9.0 Tris/EDTA修复液的比较

目的探讨pH 6.0 Citrate和pH 9.0 Tris/EDTA两种修复液在常用的免疫组化核染色标记物中的染色效果。方法选取本科室常用的3种核/浆标记抗体以及22种核标记抗体分别采用pH 6.0 Citrate和pH 9.0 Tris/EDTA微波热修复进行比较。结果在25种抗体中,其中有11种分别用pH 6.0 Citrate和pH 9.0 Tris/EDTA微波修复染色效果基本一致,在其余14种抗体中,有11种用pH 9.0 Tris/EDTA微波热修复方法进行修复时,阳性信号明显增强;而有3种抗体用pH 6.0 Citrate微波热修复方法进行修复时,阳性信号稍增强。结论对于这25种抗体来说,如果用微波加热的方法进行抗原修复,那么pH 9.0 Tris/EDTA优于PH 6.0 Citrate。

治疗伴有中至严重血小板减少的骨髓纤维化新药——枸橼酸帕西替尼(pacritinib citrate)

骨髓纤维化是一种罕见的骨髓进行性恶性肿瘤,破坏健康血细胞的正常产生,导致骨髓衰竭和严重贫血。帕西替尼(pacritinib)的激酶谱显示其对急性髓系白血病、骨髓增生异常综合征、慢性单核粒细胞白血病和慢性淋巴细胞白血病具有潜在的治疗作用。枸橼酸帕西替尼最初由美国细胞疗法公司开发,2009年1月与美国S*BIO和Onyx制药公司签订开发和商业化协议,成立美国CTI生物制药公司,重点开发枸橼酸帕西替尼,用于治疗骨髓增生和移植物抗宿主病等疾病。2012年4月,成立CTI生物制药公司,与美国S*BIO和Onyx制药公司重新签订协议,CTI将收回帕西替尼全球开发权利。2020年10月13日CTI生物制药公司向美国食品药品管理局(FDA)提交滚动新药申请,寻求批准枸橼酸帕西替尼用于治疗严重血小板减少症(血小板计数<50×10^(9)·L^(-1))的骨髓纤维化。2022年2月28日,美国FDA批准枸橼酸帕西替尼胶囊上市,商品名Vonjo®,用于治疗成人血小板计数<50×10^(9)·L^(-1)的中高危原发性或继发性(真性红细胞增多症后或原发性血小板增多症)的骨髓纤维化。该文对枸橼酸帕西替尼胶囊的非临床和临床药理毒理学、临床研究、不良反应、适应证、剂量与用法、用药注意事项及知识产权状态和国内外研究进展等进行介绍。

Efficacy of mosapride citrate with polyethylene glycol solution for colonoscopy preparation

AIM:To evaluate the efficacy and safety of adjunctive mosapride citrate for bowel preparation before colonoscopy. METHODS:We conducted a randomized,double-blind, placebo-controlled study with mosapride in addition to polyethylene glycol(PEG)-electrolyte solution.Of 250 patients undergoing colonoscopy,124 were randomized to receive 2 L PEG plus 15 mg of mosapride citrate (mosapride group),and 126 received 2 L PEG plus placebo(placebo group).Patients completed a questionnaire reporting the acceptability and tolerability of the bowel preparation process.The efficacy of bowel preparation was assessed by colonoscopists using a 5-point scale based on Aronchick's criteria.The primary end point was optimal bowel preparation rates(scores of excellent/good/fair vs poor/inadequate). RESULTS:A total of 249 patients were included in the analysis.In the mosapride group,optimal bowel preparation rates were significantly higher in the left colon compared with the placebo group(78.2%vs 65.6%,P<0.05),but not in the right colon(76.5%vs 66.4%,P=0.08).After excluding patients with severe constipation,there was a significant difference in bowel preparation in both the left and right colon(82.4%vs 66.7%,80.8%vs 67.5%,P<0.05,P<0.01).The incidence of adverse events was similar in both groups. Among the subgroup who had previous colonoscopy experience,a significantly higher number of patients in the mosapride group felt that the current preparation was easier compared with patients in the placebo group(34/72 patients vs 24/74 patients,P<0.05). CONCLUSION:Mosapride citrate may be an effective and safe adjunct to PEG-electrolyte solution that leads to improved quality of bowel preparation,especially in patients without severe constipation.

Absorption of Sulphur Dioxide with Sodium Citrate Buffer Solution in a Rotating Packed Bed

Absorption of SO2 from a SO2/air mixture with sodium citrate buffer solution was investigated using a rotating packed bed(RPB) in laboratory scale.The effects of operating parameters,such as the rotation speed of RPB,liquid-gas ratio,inlet gas flow rate,inlet concentration of SO2 in flue gas,sodium citrate buffer concentration and initial pH of absorption solution,on the SO2 concentration in the absorption solution or removal efficiency of SO2 were examined.Incremental rate of sulfate radical ions in the absorption solution was also examined.Experimental results indicate that the efficiency of this regenerative process will be improved by using RPB under appropriate operating conditions,and the generation of SO2-4 will be restrained in the process in RPB.

Removal of citrate and hypophosphite binary components using Fenton,photo-Fenton and electro-Fenton processes

Both citrate and hypophosphite in aqueous solution were degraded by advanced oxidation processes （Fe^2＋/H2O2, UV/Fe^2＋/H2O2, and electrolysis/Fe^2＋/H2O2） in this study. Comparison of these techniques in oxidation efficiency was undertaken. It was found that Fenton process could not completely degrade citrate in the presence of hypophosphite since it caused a series inhibition. Therefore, UV light （photo-Fenton） or electron current （electro-Fenton） was applied to improve the degradation efficiency of the Fenton process. Results showed that both photo-Fenton and electro-Fenton processes could overcome the inhibition of hypophosphite, especially the electro-Fenton.

Catalysis of Manganese(II) on Chromium(VI) Reduction by Citrate

The catalysis of manganese（Ⅱ） （Mn^2＋） on chromium（Ⅵ） （Cr^6＋） reduction by citrate was studied through batch experiments with the concentration of citrate greatly in excess of Cr^6＋ at 25 ℃ and in pH ranges of 4.0 go 5.0. Results showed that at pH 4.5 within 22 h direct reduction of Cr^6＋ by citrate was not observed, bug for the same time when Mn^2＋ （50 to 200 μmol L^-1） was added, nearly all Cr^6＋ was reduced, with the higher initial Mn^2＋ concentration having faster Cr^6＋ reduction. In the initial stage of the reaction, the Cr^6＋ reduction could be described with a pseudo-first-order kinetics equation. In the lager stage of the reaction, plots of lnc（Cr^6＋） versus t, where c（Cr^6＋） is the Cr^6＋ concentration in the reaction and t is the reaction time, deviated from the initial linear trend. The deviations suggested that the pseudo-first-order kinetics did not apply go the whole experimental period and that some reaction intermediates could have greatly accelerated Cr^6＋ reduction by citrate. The catalysis of the intermediates increased with the reaction time and gradually reached stability. Then, the plot of lnc（Cr^6＋） versus t in the presence of Mn^2＋ was linear again, with the rate constant increasing by 102 times compared with the absence of Mn^2＋. Complexation between Mn^2＋ and citrate was likely a prerequisite for the catalysis of Mn^2＋ on the reaction. Additional experiments showed that introducing eghylenediaminegegraacegic acid （EDTA） into the reaction system strongly suppressed the catalysis of Mn^2＋.

Can mosapride citrate reduce the volume of lavage solution for colonoscopy preparation?

AIM:To evaluate the possibility of reducing the volume of polyethylene glycol(PEG)-electrolyte solution using adjunctive mosapride citrate for colonoscopy preparation. METHODS:This was a single-center,prospective, randomized,investigator-blinded,non-inferiority study involving 252 patients of both sexes,aged from 20 to 80 years,scheduled for screening or diagnostic colonoscopy in our department.A total of 126 patients was randomized to receive 1.5 L PEG-electrolyte solution plus 15 mg of mosapride(1.5 L group),and 126 received 2 L PEG-electrolyte solution plus 15 mg of mosapride(2 L group).Patients completed a questionnaire on the acceptability and tolerability of the bowel preparation process.The efficacy of bowel preparation was assessed using a 5-point scale based on the Aronchick scale.The primary end point was adequate bowel preparation rates(score of excellent/good/fair) vs(poor/inadequate).Acceptability and tolerability,as well as disease detection,were secondary end points. RESULTS:A total of 244 patients was included in the analysis.There were no significant differences between the 2 L and 1.5 L groups in age,sex,body mass index, number of previous colonoscopies,and the preparation method used previously.The adequate bowel preparation rates were 88.5%in the 2 L group and 82.8%in the 1.5 L group[95%lower confidence limit(LCL)for the difference=-14.5%,non-inferiority P=0.019]in the right colon.In the left colon,the adequate bowel preparation rates were 89.3%in the 2 L group and 81.1%in the 1.5 L group(95%LCL=-17.0%,non-inferiority P=0.066).Compliance,defined as complete (100%)intake of the PEG solution,was significantly higher in the 1.5 L group than in the 2 L group(96.8% vs 85.7%,P=0.002).The proportion of abdominal distension(none/mild/moderate/severe)was significantly lower in the 1.5 L group than in the 2 L group (36/65/22/3 vs 58/48/18/2,P=0.040).Within the subgroup who had undergone colonoscopy previously, a significantly higher number of patients in the 1.5 L group than in the 2 L group felt that the current preparation was easier than the previous one(54.1%vs 28.0%,P=0.001).The disease detection rate was not significantly different between the two groups. CONCLUSION:Although the 1.5 L group had better acceptability and tolerability,15 mg of mosapride may be insufficient to compensate for a 0.5-L reduction of PEG solution.

Management of regional citrate anticoagulation for continuous renal replacement therapy:guideline recommendations from Chinese emergency medical doctor consensus

Continuous renal replacement therapy(CRRT)is widely used for treating critically-ill patients in the emergency department in China.Anticoagulant therapy is needed to prevent clotting in the extracorporeal circulation during CRRT.Regional citrate anticoagulation(RCA)has been shown to potentially be safer and more effective,and is now recommended as the preferred anticoagulant method for CRRT.However,there is still a lack of unified standards for RCA management in the world,and there are many problems in using this method in clinical practice.The Emergency Medical Doctor Branch of the Chinese Medical Doctor Association(CMDA)organized a panel of domestic emergency medicine experts and international experts of CRRT to discuss RCA-related issues,including the advantages and disadvantages of RCA in CRRT anticoagulation,the principle of RCA,parameter settings for RCA,monitoring of RCA(mainly metabolic acid-base disorders),and special issues during RCA.Based on the latest available research evidence as well as the paneled experts'clinical experience,considering the generalizability,suitability,and potential resource utilization,while also balancing clinical advantages and disadvantages,a total of 16 guideline recommendations were formed from the experts'consensus.

Magnesium citrate with a single dose of sodium phosphate for colonoscopy bowel preparation

AIM:To evaluate the efficacy and acceptability of magnesium citrate and a single dose of oral sodium phosphate(45 mL) solution for morning colonoscopy bowel preparation. METHODS:A total of 159 patients were randomly assigned to receive two split doses of 90 mg of sodium phosphate(GroupⅠ,n=79) or magnesium citrate(250 mL,the day before the procedure) followed by 45 mL of sodium phosphate(the day of procedure,GroupⅡ,n= 80) .The quality of bowel cleansing and the acceptability of each regimen were compared,including the satisfaction,taste,willing to repeat and adverse effects of each regimen. RESULTS:The quality of bowel cleansing of GroupⅡ was as good as that of GroupⅠ(An Aronchick scale score of good or excellent:70.9%vs 81.0%,respectively,P=0.34;the Ottawa system score:4.4±2.6 vs 3.8 ±3.0,respectively,P=0.76) .There was no statisticallysignificant difference between both groups with regard to acceptability,including the satisfaction,taste and willingness to repeat the regimen.A significantly greater number of older patients(over 65 years old) in Group Ⅱgraded the overall satisfaction as satisfactory(48.1% vs 78.1%,respectively;GroupⅠvs GroupⅡ,P=0.01) . There were no significant adverse reactions. CONCLUSION:Magnesium citrate and a single dose of sodium phosphate was as effective and tolerable as the conventional sodium phosphate regimen and is a satisfactory option.

Study on Desorbing Sulfur Dioxide from Citrate Solution by Ultrasonlficatlon

Using a sonochemical reactor designed by the authors,the process of removing sulfur dioxide from cit- rate solution simulating the flue gas desulfurization was studied.The influence of ultrasonic frequency,ultrasonic power,reaction temperature,stirring speed,inert gases,initial concentration of sulfur dioxide and concentration of citrate on the efficiency of sulfur dioxide desorption,the stability of citrate solution and the concentration of sulfate radical was examined systematically.By comparing the desorption of sulfur dioxide with and without ultrasonifica- tion,it was concluded that(1)lower ultrasonic frequency results in a better degassing efficiency;(2)the use of ul- trasonification in desorbing sulfur dioxide from citrate solution improves the desorbing efficiency in some condi- tions,without changing the essence of chemical reactions;(3)sparging inert gas into the liquid can lower the vis- cosity of solution and the cavitating threshold,and raise the desorption efficiency.These results demonstrate a technical way for deep desorption of sulfur dioxide and provide the fundamental data for future industrial disposal of sulfur dioxide.

Competitive and cooperative adsorption of arsenate and citrate on goethite

The fate of arsenic in natural environments is influenced by adsorption onto metal （hydr）oxides. The extent of arsenic adsorption is strongly affected by coexisting dissolved natural organic acids. Recently, some studies reported that there existed competitive adsorption between arsenate and citrate on goethite. Humic acid is known to interact strongly with arsenate by forming complexes in aqueous solution, hence it is necessary to undertake a comprehensive study of the adsorption of arsenate/citrate onto goethite in the presence of one another. The results showed that at the arsenate concentrations used in this study （0.006-0.27 mmol/L）, citrate decreased arsenate adsorption at acidic pH but no effect was observed at alkaline pH. In comparison, citrate adsorption was inhibited at acidic pH, but enhanced at alkaline pH by arsenate. This was probably due to the formation of complex between arsenate and citrate like the case of arsenate with humic acid. These results implied that the mechanism of the adsorption of arsenate and citrate onto goethite in the presence of one another involved not only competition for binding sites, but the cooperation between the two species at the watergoethite interface as well.

Assessment of heme oxygenase-1 （HO-1） activity in the cavernous tissues of sildenafil citrate-treated rats

Aim： To assess heine oxygenase-1 （HO-1） activity in the cavemous tissue of sildenafil citrate-treated rats. Methods： One hundred and ninety-two Sprague-Dawley male rats, divided into four equal groups, were investigated. Group 1, the control group, received regular animal chow; group 2 received sildenafil citrate by intragastric tube; group 3 received sildenafil and HO inhibitor （zinc protoporphyrin, ZnPP）; and group 4 received sildenafil and nitric oxide synthase （NOS） inhibitor L-nitroarginine methyl ester （L-NAME）. Twelve rats from each group were killed after 0.5 h, 1 h, 2 h and 3 h of drug administration. Then HO-1 activity, cGMP levels and NOS enzymatic activity in the cavernous tissues were estimated. Results： In cavemous tissue, HO-1 activity, NOS enzymatic activity and cGMP concentration increased significantly in sildenafil-treated rats compared to other groups throughout the experiment. Rats receiving either HO or NOS inhibitors showed a significant decrease in these parameters. HO- 1 cavemous tissue activity and NOS enzymatic activity demonstrated a positive significant correlation with cGMP levels （r = 0.646, r = 0.612 respectively; P 〈 0.001）. Conclusion： The actions of PDE5 inhibitor sildenafil citrate in the cavernous tissue are partly mediated through the interdependent relationship between both HO-1 and NOS activities.