Plasma adrenaline: relations to blood pressure, blood platelet function and blood lipids in essential hypertension.

For various reasons plasma catecholamines should be measured in arterial blood when comparing hypertensive and normotensive groups (1, 2). Measurements of plasma catecholamines in peripheral venous blood may conceal important hypertensive-normotensive differences (2). Plasma catecholamines seem to be subjected to a peripheral arterialvenous fractional extraction of approximately 50%. Thus, arterial adrenaline represents the effective adrenaline concentration to which the tissues are exposed. Besides, plasma noradrenaline in peripheral venous blood mainly represents local release related to skeletal muscle sympathetic tone which seems unchanged in essential hypertension ( 3 ) .