Relations of vascular calcium channels with blood pressure and endotheliumin hypertension and with aging

To investigate the relationships between the activity in potential operated Ca2+ channels (POC), blood pressure, and endothelium in hypertension, we t ested the contractile responses to a Ca2+ channel agonist Bay K 8644 (BAY K ) in aorta from deoxycorticosterone-acetate-saline (DOCA-S) and reduced ren al mass-saline (RRM-S) hypertensive rats. The effects of mechanical rubbing , N omega-Nitro-L-Arginine Methyl Ester (l-NAME) and indomethacin were also examined. Sensitivity to BAY K increased in experimental rats before they became hypertensive and contractile responses were enhanced as hypertension developed. Force development to BAY K was correlated with blood pressure l evels. Endothelium removal enhanced the contractile response to BAY K. L NA ME, but not indomethacin, potentiated the response to BAY K. Contractile re sponse to BAY K was negatively correlated with relaxation to acetylcholine. An enhanced contractile response to BAY K was observed also in aged rats. Enhanced activation of vascular POC in hypertension results from elevated b lood pressure and partly from diminished inhibitory action of endothelium. Senescence also enhances vascular POC activity.