Role Of Ampkαin Aerobic Exercise-Induced Regulation Of The Function Of Ca_L Channel In Mesenteric Arterial Smooth Muscle In Hypertension

Objective:To investigate the role of AMPKαin aerobic exercise-induced regulation of the inverse remodeling of Ca _L channel in mesenteric arterial smooth muscle in Spontaneously hypertensive rat(SHR).Methods:Twelve-weeks-old,male,Wistar-Kyoto(WKY)and SHR were randomly divided into sedentary groups(WKY-SED,SHR-SED)and exercise training groups(WKY-EX,SHR-EX),respectively.The exercise training groups underwent moderate-intensity treadmill running for 12 weeks after one-week adaptation.The basic indicators such as body weight(BW),systolic blood pressure(SBP),diastolic blood pressure(DBP)and mean arterial pressure(MAP)of each group were measured before and after the experiment.After the intervention,the mesenteric arteries were obtained to investigate the effect of Ca _L channel agonist(Bay K8644),inhibitor(Nifedipine)and AMPKαspecific agonist(PT1)on the vascular tone by using isometric contraction test.The smooth muscle cells from the mesenteric arteries were separated by enzyme digestion to measure the Ca _Lchannel current and the impact of AMPKαon its current by using the whole-cell patch clamp technique.Western blotting was performed to detect the expression of Ca _L channelα1C subunit,AMPKα,p-AMPKαand the effect of aerobic exercise on it.Results:1)The body weight of SHR-SED group was significantly lower than that of WKY-SED group(P<0.05),but the blood pressure(including SBP,DBP,MAP)was significantly higher than that of WKY-SED group(P<0.05);Aerobic exercise training significantly reduced the BW and blood pressure(BP)of SHR(P<0.05).2)The sensitivity of the Ca _L channel agonist Bay K8644 and the inhibitor Nifedipine was significantly higher in the SHR-SED group than that in the WKY-SED group(P<0.05).However,aerobic exercise training could effectively inhibit the increased sensitivity of the SHR to Bay K8644 and Nifedipine(P<0.05).3)PT1,the specific AMPKαagonist induced vasodilation,and the sensitivity of PT1 was significantly higher in the SHR-SED group than that in WKY-SED group(P<0.05);compared with the SHR-SED group,the sensitivity of mesenteric artery to PT1 in SHR-EX group was significantly lower(P<0.05).4)PT1 reduced the amplitude of Ca _L channel current in each group.Compared with WKY-SED group,the SHR-SED group showed a great reduction in Ca _L channel current(P<0.05),while aerobic exercise significantly inhibited the response of Ca _L channel to PT1 in SHR(P<0.05).5)Immunoblotting results showed that the expression of Ca _L channelα1C subunit was significantly up-regulated during hypertension.After 12 weeks of aerobic exercise,the expression ofα1C subunit in the SHR-EX group was down-regulated(P<0.05).Compared with the WKY-SED group,the expression of p-AMPKαin the SHR-SED group was significantly reduced(P<0.05),and there was no significant difference in the expression of AMPKα(P>0.05).After the intervention,the expression of p-AMPKαprotein in the WKY-EX and SHR-EX groups was significantly increased,but there was no significant difference in AMPKαbetween the groups(P>0.05).Conclusions:aerobic exercise can effectively inhibit the up-regulation of Ca _Lchannel function in hypertensive mesenteric arterial smooth muscle cells,thereby improving the diastolic function of the resistance arteries in hypertensive rats,lowering blood pressure;in this process,in addition to inhibiting the expression of Ca _L channelα1C subunit to improving the function of Ca _L channel,the activation of AMPKαand then inhibit the function of Ca _L channel is also one of its important mechanisms.