| Objective:In China,cardiovascular diseases take the first place among all the diseases,and hypertension is the most important risk factor.Old age itself is also a risk factor for cardiovascular diseases.The harm of hypertension increases significantly with aging,but the mechanism needs to be clarified.The binding of thromboxane A2?TXA2?to its specific TXA2 receptor?TXA2R?can induce a variety of biological effects and participate in a variety of pathological changes,including hypertension,atherosclerosis and so on,but its roles in aging and hypertension are rarely reported.Ion channels are widely involved in the regulation of vascular function.Large-conductance calcium-activated potassium channels(BKCa)and calcium channels play an important role in the regulation of vascular tension in cardiovascular diseases.Transient receptor potential channel?TRPs?can regulate intracellular calcium concentration,forming macromolecule complexes with BKCa,and their roles in cardiovascular diseases,especially hypertension-related vascular function regulation are gradually recognized.Immunoprecipitation and functional experiments confirmed that BKCaa channel and Transient Receptor Potential Vanillin Receptor 4 Channel?TRPV4?may form a complex.The TRPV4-BKCaa channel complex,couples with the vasodilation and plays an important role in the regulation of arterial contraction induced by vasoconstrictors.However,most of these studies have been carried out in normal animal models.In the state of diseases,such as hypertension,whether the expression and function of BKCaa channel/Ca2+-permeable channels complex are abnormal and whether these complexes are the key factors affecting vascular function,there are no related reports.There are great basic and clinical significances to explore and reveal the functional changes of these channels and their complexes under diseases.This topic mainly carried on the following researches:?1?changes of mesenteric artery responsiveness to vasoconstrictor?9,11 Dideoxy11a,9a epoxy methanoprostaglandin F2?,U46619?in aged hypertensive rats.?2?Changes of vasodilation effects of U46619-pretreated mesenteric artery after activation of TRPV4 channel.?3?Changes of vasodilation effects of U46619-pretreated mesenteric artery,after blocking TRPV4 channel and BKCaa channel.?4?Comparing the expressions of thrombus A2 signaling pathway associated proteins,TRPV4 channel protein and BKCaa channel protein in mesenteric artery from WKY rats,SHR,WKY-old rats and SHR-old.Methods:The experimental animals were divided into Wistar Kyoto rats?WKY group,16 weeks old,normal blood pressure?,spontaneous hypertensive rats?SHR group,16 weeks old,hypertension?,old Wistar Kyoto group?WKY-old group,?18 months old,normal blood pressure?,and old spontaneous hypertensive rats group?SHR-old group,?18 months old,hypertension?.Male animals were used in all experiments.After all of the four groups were anesthetized with 1%pentobarbital sodium?5mL/Kg?and blood pressure and blood glucose were measured to obtain the basic physiological data.Fresh mesenteric arteries were separated for HE,mason staining,vascular tension determination,western blotting and immunohistochemical study.Results:1.To compare the differences of vasoconstriction induced by1?mol/L U46619 and 60 mmol/L high K+in isolated mesenteric artery of WKY rats,SHR,WKY-old rats and SHR-old.The maximum contractions?Emax?induced by 1?mol/L U46619 in isolated mesenteric artery of WKY rats,SHR,WKY-old rats and SHR-old were 5.95±2.78 mN,9.07±3.66 mN,0.33±0.31 mN,0.57±0.47 mN,respectively.The maximum contractions percentage?%Emax?induced by 1?mol/L U46619 relative 60 mmol/L high K+were 56.0±20.85%,76.0±19.55%,3.03±2.99%and 4.50±3.54%,respectively.?SHR,WKY-old rats vs WKY rats,SHR-old vs SHR,P<0.001?The maximum contractions?Emax?induced by 60 mmol/L high K+in isolated mesenteric artery of WKY rats,SHR,WKY-old rats and SHR-old were 11.6±1.21 mN,14.21±2.72 mN,11.54±1.89 mN and 13.55±2.35 mN,respectively.?SHR vs WKY rats,P<0.01;SHR-old vs WKY-old rats,P<0.05?2.To compare the differences of vasodilation response to TRPV4 channel agonist GSK1016790A in isolated mesenteric artery of WKY rats and SHR.U46619 1?mol/L precontracted the mesenteric artery of WKY rats and SHR in vitro and when the vessels reached the maximum contraction,GSK1016790A 10-910-77 mol/L relaxed the mesenteric artery of WKY rats and SHR.The results showed that when the concentration of GSK were 5×10-88 mol/L and 10-77 mol/L,the relaxation effects of SHR mesenteric arteries were significantly decreased,compared with WKY rats.?40.74±13.64%vs 58.52±19.53%,50.36±15.41%vs 72.71±18.32%,SHR vs WKY rats,P<0.01 respectively?3.To compare the differences of vasodilation effects induced by TRPV4channel agonist GSK1016790A after blocking BKCaa channel and TRPV4channel in isolated mesenteric arteries of WKY rats.?1?For the same vascular ring,after incubated with TEA or IbTX for 30 minutes,U466191?mol/L precontracted artery of WKY rats and when the vessels reached the maximum contraction,GSK1016790A 10-910-77 mol/L relaxed the mesenteric artery of WKY rates.The results showed that when the concentration of GSK1016790A in the TEA treatment group were 10-8mol/L,5×10-88 mol/L and 10-77 mol/L,the relaxation effects of mesenteric artery were significantly decreased,compared with the control group.?12.30±21.47%vs 43.74±25.73%,18.78±29.8%vs58.52±19.53%,P<0.05;28.60±30.77vs 72.71±18.32%,P<0.01 TEA treated group vs control??2?For the same vascular ring,after incubated with RN1734 for 30 minutes,U46619 1?mol/L precontracted the artery of WKY rats and when the vessels reached the maximum contraction,GSK1016790A 10-910-77 mol/L relaxed the mesenteric artery of WKY rats.The results showed that the relaxation effects of mesenteric artery were significantly decreased when the concentration of GSK1016790A in the TEA treatment group were 5×10-88 mol/L and 10-77 mol/L,compared with the control group.?35.66±14.44%vs 58.52±19.53%,49.35±9.43%vs 72.71±18.32%,RN1734 treated group vs control,P<0.05respectively?4.To compare the differences of vasodilation effects induced by TRPV4channel agonist GSK1016790A after blocking BKCaa channel and TRPV4channel in isolated mesenteric artery of SHR.?1?For the same vascular ring,after incubated with TEA or IbTX for 30 minutes,U46619 1?mol/L precontracted the artery of SHR and when the vessels reached the maximum contraction,GSK1016790A 10-910-77 mol/L relaxed the mesenteric artery of SHR.The results showed that the relaxation effects of mesenteric artery were significantly decreased when the concentrations of GSK1016790A in the TEA treatment group were 5×10-88 mol/L and 10-7mol/L,compared with the control group.?29.89±20.0%vs 40.74±13.64%,36.30±24.31%vs 50.36±15.41%,TEA treated group vs control,P<0.05respectively??2?For the same vascular ring,after incubated with RN1734for 30 minutes,U46619 1?mol/L precontracted the artery of SHR and when the vessels reached the maximum contraction,GSK1016790A10-910-77 mol/L relaxed the mesenteric artery of SHR.The results showed that there were no significant difference in RN1734 treatment group,compared with the control group.5.Comparison the expression differences of relevant proteins in the TXA2R signaling pathway and TRPV4 channel protein and BKCaa channel protein.The results showed that in the mesenteric artery of SHR,WKY-old rats,SHR-old,the expression of thromboxane A2 receptor protein,TLR4?Toll-like recepter 4?and Cyclooxygenase-2?COX-2?were up-regulated in different degrees.The expression of BKCaa channel protein and TRPV4 channel protein were down-regulated in different degrees.Conclusion:1.Thrombus A2 analog U46619 enhanced significantly the maximum contraction of mesenteric artery in SHR,but U46619 could hardly induce the contraction of mesenteric artery in WKY-old rats and SHR-old.2.The maximum contraction of mesenteric artery induced by 60 mmol/L high K+in SHR and SHR-old increased significantly.3.ThrombusA2 signaling pathway associated proteins?TLR4,COX-2,TXA2R?were related to the pathological processes of hypertension and aging.however,hypertension and aged hypertension are two different kinds of pathological processes.4.For the mesenteric artery of SHR,the reduction of relaxation effects mediated by TRPV4-BKCaa complex were associated with the down regulation of TRPV4 channel protein and BKCa?1 protein on vascular smooth muscle. |
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