Plasma Catecholamines and the Pressor Response to Sar1-Ala8-Angiotensin II in Man

Publisher Website
Google Scholar
Abstract
The initial blood pressure response to saralasin (Sar1-Ala8-angiotensin II) infusion was examined in 15 normal subjects, 8 patients with untreated essential hypertension and 65 patients established on chronic hemodialysis (including 6 anephric patients), and related to measurements of plasma renin activity (PRA), angiotensin II, plasma catecholamines (noradrenaline [norepinephrine] and adrenaline [epinephrine]), blood volume and extracellular fluid volume 35S-sulfate space or exchangeable Na). A transient rise in arterial pressure, maximum after 5-6 min, occurred in all normal subjects, patients with essential hypertensohypertension and anephric patients, and in 41 of 59 dialysis patients with kidneys. In normal subjects, saralasin infusion resulted in a significant rise in plasma noradrenaline (mean increase 360%, P < 0.02) without change in plasma adrenaline concentration. Change in noradrenaline was significantly related to change in mean blood pressure (P < 0.05) and was similar to the response to 5 min of a 40.degree. head-up tilt. Increase in plasma noradrenaline occurred in dialysis patients (P < 0.005), but change in mean blood pressure with saralasin in this group was inversely related to PRA (P < 0.001) and angiotensin II (P < 0.001), directly related to blood volume (P < 0.001), but unrelated to change in plasma noradrenaline. The pressor response to saralasin may be mediated not only by angiotensin-like action on vascular receptors but also by an action on the CNS or peripheral autonomic nervous system.