Roles And Mechanisms Of AKAP150 In Aerobic Exercise-induced Improvement Of Cerebral Arterial Function In Essential Hypertension

Aims:The vascular smooth muscle voltage-gated L-type Ca²⁺channel（LTCC）is a principal mediator in regulating arterial tone and blood pressure.A-kinase anchoring protein AKAP150,facilitating transduction events by binding multiple signaling enzymes to specific cellular microdomains,plays a central role in ion channel remodeling in vascular during hypertension.Aerobic exercise is an effective prevention and treatment of essential hypertension,however,the cellular mechanism underlying is unclear.In the present study,we focused on AKAP150,investigating the role of LTCC in aerobic exercise-induced improvement of cerebral arterial function in essential hypertension.Furthermore,we investigated the mechanism of AKAP150/protein kinase Cα（PKCα）signaling pathway in exercise-mediated LTCC function of cerebral arteries during hypertension.Methods:12-week-old male spontaneously hypertensive rats（SHR）and Wistar-Kyoto（WKY）rats were randomly assigned to sedentary（WKY-SED,SHR-SED）and exercise training（WKY-EX,SHR-EX）groups,respectively.Exercise groups were performed a moderate-intensity treadmill running.After 12 weeks,femoral venous and arterial cannular surgery,artery contraction myography,patch-clamp electrophysiology,TIRF Ca²⁺image,immunofluorescence and Western blot were used to detect cardiovascular responses,cerebral vascular tone,LTCC whole-cell and single channel currents,Ca²⁺sparklets,and AKAP150/PKCαsignaling pathway.In vitro experiment,cerebral arteries were transfected with AKAP150shRNA,then cultured in medium supplemented with angiotensin II（AngII）.Transfected arteries were used to detect AKAP150,LTCCα_1c subunit expression,and cerebral arterial contractility.Results:（1）Aerobic exercise significantly reduced body weight,systolic blood pressure,diastolic blood pressure and mean arterial pressure in SHR-EX（all P<0.05）.（2）After aerobic exercise,Ang II,Bay K8644-stimulated increases and nifedipine-stimulated decreases of SBP in SHR-EX were significantly lower than that of SHR-SED,respectively（all P<0.05）.（3）Aerobic exercise significantly attenuated the LTCC contribution to cerebral vascular tone regulation;and inhibited SHR-induced increases in LTCC currents in cerebral arterial myocytes（both P<0.05）.（4）The LTCC channel open probability（nP_o）and persistent Ca²⁺sparklet activity（nPs）of cerebral arterial myocytes were significantly reduced in SHR-EX as compared with SHR-SED cells（both P<0.05）.（5）Aerobic exercise significantly suppressed hypertension-associated increases of PKCαactivity,which was shown to reduce PKCαcontribution to vascular tone regulation,LTCC single channel and whole-cell currents（all P<0.05）.（6）The protein expression of AKAP150 in cerebral arterial smooth muscle was significantly up-regulated in SHR-SED（P<0.05）,while down-regulated in SHR-EX（P<0.05）.（7）Plasma membrane-localized AKAP150 and sarcolemmal PKCαtranslocation were significantly reduced in SHR-EX as compared with SHR-SED myocytes（both P<0.05）.（8）The colocalization rate of AKAP150 and PKCα,PKCαand LTCCα_1c subunits at the sarcolemma were lower in cerebral arterial myocytes from SHR-EX than in SHR-SED cells（both P<0.05）.（9）Aerobic exercise significantly decreased plasma Angiotensinogen（AGT）and Ang II levels in SHR-EX（both P<0.05）,and inhibited LTCC channel activation by Ang II in hypertensive myocytes（P<0.05）.（10）The protein expression of AKAP150,as well as LTCC and PKCαcontribution to the regulation of cerebral vascular tone were significantly elevated in 24 h Ang II treated cerebral arteries（all P<0.05）.（11）The LTCC and PKCαcontribution to cerebral vascular tone regulation were reduced after AKAP150 knockdown（both P<0.05）,which were unchanged in AKAP150knockdown and Ang II treated arteries（P>0.05）.Conclusion:（1）Aerobic exercise effectively reduces blood pressure,prevents the upregulation of LTCC function in vascular smooth muscle,and ameliorates cerebral arterial function during hypertension.（2）Aerobic exercise inhibits sarcolemmal PKCαtranslocation,LTCC channel activity and persistent Ca²⁺sparklets via suppression of AKAP150 protein expression,and so alleviates the enhanced arterial tone of SHR.（3）AKAP150 knockdown in vitro attenuates Ang II-induced activation in LTCC and PKCαcontribution to cerebral vascular tone regulation,which contributes to the reduction of enhanced arterial tone by Ang II.