Experimental Study on AT1-receptor-peptide-induced Myocardial Immune Damage in Rat

In order to investigate the immunological damage in rat immunized with AT1-receptor peptide, 18 male Wistar rats were divided into two groups: immunized-group (n=12), each rat was immunized with 150 μg AT 1-receptor petide coupled to bovine serum albumin, together with Freund's adjuvant. Control group (n=6), sham-immunized, 'immunized liquid' was same as immunized-group except AT1-receptor peptide. Systolic blood pressure (SBP) was measured by using the tail-cuff technique, antibody against AT1-receptor peptide detected by using ELISA method, and left ventricular myocardium and renal cortex sections were observed under light and electron microscopy. There was no significant difference in SBP and light microscopic observation of the tissue sections between the immunized-group and control group. The O.D. value of anti-AT1-receptor peptide antiserum was significantly higher in the immunized-group than in the rats before immunization and control group (P<0.01). Positive rate in the immunized-group was 100 %, while 0 % in the control group. Ultramicroscopic morphology showed potential myocardial injury, including: increase in number of mitochondria, swelling of many mitochondria with reduction in number or absence of their cristae and cristolysis, disorder of the cardiac myofibrils, and myofibrillar disruption and myocytolysis. And lysosomes were increased in renal tubular epithelia. The AT1-receptor peptide could induce to generate the antibody against AT1-receptor peptide and lead to myocardial and renal damage in rats.

EFFECT OF α_1 AND α_2 RECEPTORS IN THE RABBIT THORACIC SPINAL CORD ON ELECTROACUPUNCTURE AT "NEIGUAN" FOR TREATMENT OF ACUTE MYOCARDIAL ISCHEMIA

In the present paper, the effect of α1 and α2 subtypes of the thoracic spinal cord on electroacupuncture (EA)-induced improvement of ischemic cardiac electrical and mechanical activities was observed in 80 anesthetized rabbits by using ECG-ST, MBP, LVP and dp/dt max as indexes. Results showed that:1) EA at "Neiguan" could significantly improve the electrical and mechanical activities of the ischemic heart; 2) the effect of EA could be enhanced to a certain degree when α1 receptors of the thoracic spinal cord were activated by subarachnoid microinjection of phenylephrine, while it was weakened when α1 receptors were inhibited by microinjection of parison; and 3) activation or inhibition of α2 receptors of the thoracic spinal cord by microinjection of clonidine and yohimbine had no marked influence on the effect of EA in improving electrical activity of the ischemic heart, but when activated,they could weaken the effect of EA in raising MBP; while suppressed, they had no any striking influence on the effect of EA in raising MBP. It suggests that among α-receptors, predominantly α1-receptors participate in the process of EA-induced improvement of performance of ischemic heart.

Effect of nonpeptide NK1 receptor antagonist L-703,606 on the edema formation in rats at early stage after deep partial-thickness skin scalding

Objective:To investigate the effect and the relevant potential mechanism of nonpeptide neurokinin 1(NK1) receptor antagonist L-703,606 in the edema formation after burn injury. Method:1.-703,606 treatment was performed in Sprague-Dawley(SD) rats at early stage after deep partial-thickness skin scalding.One hundred and fifty two adult male SI) rats were used in the study and randomly divided into sham scald(SS,n=8),scald control(SC,n=48),and L-703,606 treatment(IT,n=48) groups.The rats in SC and LT groups were subjected to 20%total body surface area(TBSA) deep partial-thickness skin scalding.Modified Evans blue extravasation, tracing electron microscopy by lanthanum nitrate and mean water content assay were employed to observe and detect the changes of vascular permeability,ultrastructure and edema formation in adjacent tissue to the wounds and in the jejuna of rats at early stage(72 h) after scald.Results: The pathological increase of vascular permeability in the periwound tissue and jejunum of rats in LT group were significantly lower than that in SC group(P【0.01),and recuperated earlier. Meanwhile,the changes of water contents of corresponding tissues in LT group were lighter than those in SC group(P【0.01).The ultrastructural changes of the microvessels in the peri-wound tissue of LT group showed that the junctions between microvascular endothelium cells were more narrow than those of SC group,moreover,and the number of opening and the engorgement and cavitation of the vascular endothelium cells decreased,the areosis and edema in perivascular tissue lightened,and the precipitation of the high eletron density lanthanum tracing agent in the interspace of the tissue decreased significantly in LT group.Conclusions:It is concluded that nonpeptide NK1-receptor antagonist L-703,606 could lighten the vascular permeability and edema formation in the periwound tissue and jejunum,and accelerate the normalization process of pathological changes in the tissues of rats after scald.

Human ciliary muscle cell responses to kinins:Activation of ERK1/2 and pro-matrix metalloproteinases secretion

AIM To study activation of extracellular signal-regulated kinase-1/2(ERK1/2) and pro-matrix metalloproteinases(pro-MMPs) secretion from isolated primary human ciliary muscle(h-CM) cells in response to bradykinin(BK) and other agonists. METHODS Serum-starved h-CM cells were challenged with vehicle, BK agonists or antagonists. Cell lysates were evaluated for phosphorylated ERK1/2 using homogeneous timeresolved fluorescence technology based on a sandwich immunoassay. Rabbit polyclonal anti-pro-MMP antibodies were used to measure pro-MMPs using immunoblot analysis.RESULTS A 10 min incubation time using 5 × 104 h-CM cells/well was optimum condition for studying stimulation of ERK1/2 phosphorylation. BK(100 nmol/L) caused a 1.86 ± 0.26 fold(n = 3) increase in ERK1/2 phosphorylation above baseline. BK analogs, Met-Lys-BK and RMP-7(100 nmol/L), also stimulated ERK1/2 phosphorylation by 1.57 ± 0.04 and 1.55 ± 0.09 fold, respectively. However, DesArg9-Bradykinin, a B1 receptor-selective agonist(0.1-1 μmol/L), was essentially inactive. HOE-140 or WIN-64338(B2-antagonists) appreciably blocked phosphorylation of ERK1/2 induced by various BK agonists. Pre-treatmentof cells with a prostaglandin(PG) synthase inhibitor(bromfenac; 1 μmol/L) failed to alter kinin-induced ERK1/2 activation. BK and a non-peptide BK agonist(FR-190997)(10 nmol/L-1 μmol/L) also enhanced pro-MMPs secretion(pro-MMP-1 > pro-MMP-3 > pro-MMP-2; 1.45-1.75-fold over baseline) from h-CM cells. CONCLUSION These collective data suggest that B2 kinin receptors initiate signaling in h-CM cells by a relatively rapid mechanism(within minutes) involving ERK1/2 activation which in turn regulates MMPs production(within hours). The latter process does not involve PGs.