Rat Coronary Endothelial Cell Membrane Potential Responses During Hypertension

-The purpose of this study was to provide the first membrane potential profile in coronary endothelial cells from normotensive sham-operated control and 1-kidney, 1-clip renal hypertensive rats. Dilator responses were assessed in cannulated coronary arteries from control and 1-kidney, 1-clip rats, and the perforated patch-clamp method was used to compare membrane potential responses between the intact endothelial cells. Under these conditions, acetylcholine (100 pmol/L to 10 µmol/L) induced similar large dilations of coronary arteries from control and 1-kidney, 1-clip rats that were associated with endothelial cell hyperpolarizing responses of 16+/-3 and 18+/-2 mV, respectively. Substance P (10 fmol/L to 1 nmol/L) and bradykinin (100 fmol/L to 10 nmol/L) also substantially dilated coronary arteries from control rats but only induced small (2 to 4 mV) endothelial cell hyperpolarizing responses. These dilations, which appeared independent of membrane potential changes, were highly blunted or absent in arteries from 1-kidney, 1-clip rats. Thus, dilator responses to acetylcholine that are associated with large endothelial hyperpolarizing responses are normal in the small coronary arteries of 1-kidney, 1-clip rats. However, dilator response to substance P and bradykinin, which apparently are not heavily dependent on endothelial cell hyperpolarizations, are selectively targeted for impairment in the coronary arteries of this model of hypertension