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Low K+ current in arterial myocytes with impaired K+-vasodilation and its recovery by exercise in hypertensive rats

저자

Seo EY, Kim HJ, Zhao ZH, Jang JH, Jin CZ, Yoo HY, Zhang YH, Kim SJ

저널 정보

Pflugers Archiv European Journal of Physiology

출간연도

Nov 2014

K+ channels determine the plasma membrane potential of vascular myocytes, influencing arterial tone. In many types of arteries, a moderate increase in [K+]e induces vasorelaxation by augmenting the inwardly rectifying K+ channel current (IKir). K+-vasodilation matches regional tissue activity and O2 supply. In chronic hypertension (HT), small arteries and arterioles undergo various changes; however, ion channel remodeling is poorly understood. Here, we investigated whether K+ channels and K+-induced vasodilation are affected in deep femoral (DFA) and cerebral artery (CA) myocytes of angiotensin II-induced hypertensive rats (Ang-HT). Additionally, we tested whether regular exercise training (ET) restores HT-associated changes in K+ channel activity. In Ang-HT, both the voltage-gated K+ channel current (IKv) and IKir were decreased in DFA and CA myocytes, and were effectively restored and further increased by combined ET for 2 weeks (HT-ET). Consistently, K+-vasodilation of the DFA was impaired in Ang-HT, and recovered in HT-ET. Interestingly, ET did not reverse the decreased K+-vasodilation of CA. CA myocytes from the Ang-HT and HT-ET groups demonstrated, apart from K+ channel changes, an increase in nonselective cationic current (INSC). In contrast, DFA myocytes exhibited decreased INSC in both the Ang-HT and HT-ET groups. Taken together, the decreased K+ conductance in Ang-HT rats and its recovery by ET suggest increased peripheral arterial resistance in HT and the anti-hypertensive effects of ET, respectively. In addition, the common upregulation of INSC in the CA in the Ang-HT and HT-ET groups might imply a protective adaptation preventing excessive cerebral blood flow under HT and strenuous exercise.