Research on Age-Related Changes of BKCa in Renal Artery Smooth Muscle Cells of Spontaneously Hypertensive Rats

Objective To observe the changes of large-conductance calcium-activated potassium channels(BKCa,MaxiK) during aging and its relationship with blood pressure.Methods Thirty male spontaneously hypertensive rats(SHR) and normal rats aged 9,15,21,27,33 weeks were selected as SHR group and control group.Abdominal aortic blood pressure of rats in SHR and control groups were measured.The potassium current,the current of BKCa was blockaded by Tetraethylammonium(TEA) and the capacitance membrane(Cm) of the vascular smooth muscle cells(VSMCs) of renal artery were recorded using whole cell patch clamp,and the BKCa current,the potassium current and the BKCa current density were calculated.Results The mean abdominal aortic blood pressure(MABP) of SHR was obviously higher than normal(P0.001),while MABP of the normal rats was still normal.The MABP of SHR and normal rats all had tended to heighten with aging.The Cm of SHR group increased during aging,but normal group did not.The BKCa current density of SHR group decreased during aging,but the changes of normal group were not significant(P0.05).The BKCa current density and Cm were negatively related with MABP in SHR group(r=-0.7962,r=-0.7361),and BKCa current density was poorly related with MABP in normal group(r=-0.4761).Conclusions BKCa current density of SHR attenuated with aging.The process of attenuation is complex and have high correlation with blood pressure during aging.