Rat Coronary Endothelial Cell Membrane Potential Responses During Hypertension

Area of Science:

• Cardiovascular Physiology
• Renal Hypertension Research
• Endothelial Cell Biology

Background:

• Hypertension can alter vascular function in coronary arteries.
• Endothelial cell membrane potential plays a crucial role in regulating vascular tone.
• Previous studies have not fully characterized membrane potential changes in coronary endothelial cells during hypertension.

Purpose of the Study:

• To investigate and compare membrane potential profiles in coronary endothelial cells of normotensive and hypertensive rats.
• To assess the impact of hypertension on dilator responses mediated by acetylcholine, substance P, and bradykinin.
• To correlate endothelial cell membrane potential changes with vascular smooth muscle relaxation in a rat model of hypertension.

Main Methods:

• Utilized the 1-kidney, 1-clip rat model to induce renal hypertension.
• Employed cannulated coronary arteries for assessing dilator responses.
• Applied the perforated patch-clamp technique to measure membrane potential in intact endothelial cells.

Main Results:

• Acetylcholine induced similar large dilations and hyperpolarizing responses in coronary arteries from both control and hypertensive rats.
• Substance P and bradykinin caused significant dilations and hyperpolarizations in control rats, but these responses were blunted in hypertensive rats.
• Dilations to substance P and bradykinin in hypertensive rats were largely independent of significant membrane potential changes.

Conclusions:

• Coronary endothelial cell hyperpolarizing responses to acetylcholine remain intact in the 1-kidney, 1-clip model of hypertension.
• Dilator responses to substance P and bradykinin are selectively impaired in the coronary arteries of hypertensive rats.
• Hypertension differentially affects endothelial-dependent vasodilation, targeting pathways not solely reliant on large membrane potential shifts.