Aerobic exercise of low to moderate intensity corrects unequal changes in BK(Ca) subunit expression in the mesenteric arteries of spontaneously hypertensive rats.

Abstract

Accumulating evidence indicates that hypertension is associated with "ion channel remodeling" of vascular smooth muscle cells (VSMCs). The objective of this study was to determine the effects of exercise intensity/volume on hypertension-associated changes in large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels in mesenteric arteries (MAs) from spontaneously hypertensive rats (SHR). Male SHRs were randomly assigned to three groups: a low-intensity aerobic exercise group (SHR-L: 14 m/min), a moderate-intensity aerobic exercise group (SHR-M: 20 m/min), and a sedentary group (SHR). Age-matched Wistar-Kyoto rats (WKYs) were used as normotensive controls. Exercise groups completed an 8-week exercise program. Elevation of the alpha and beta1 proteins was unequal in MA myocytes from SHRs, with the beta1 subunit increasing more than the alpha subunit. BK(Ca) contribution to vascular tone regulation was higher in the myocytes and arteries of SHRs compared to WKYs. SHR BK(Ca) channel subunit protein expression, beta1/alpha ratio, whole cell current density and single-channel open probability was also increased compared with WKYs. Aerobic exercise lowered systemic blood pressure and normalized hypertension-associated BK(Ca) alterations to normotensive control levels in the SHRs. These effects were more pronounced in the moderate-intensity group than in the low-intensity group. There is a dose-effect for aerobic exercise training in the range of low to moderate-intensity and accompanying volume for the correction of the pathological adaptation of BK(Ca) channels in myocytes of MAs from SHR.