Relationship of the renin-angiotensin system and systemic arterial pressure to sodium excretion during atrial natriuretic peptide infusion in men.
The goal of this study was to evaluate the relative contribution of the renin-angiotensin system and mean arterial pressure to sodium excretion and urine flow rate during an infusion of atrial natriuretic peptide (ANP) at physiologically relevant doses in humans. Eight normal volunteers were studied during five periods: (1) baseline in the supine position; (2) during an infusion of ANP at physiologic doses (0.01 micrograms/kg/min) in the supine position; (3) during ANP infusion and 60 degrees head-up tilt; (4) during ANP infusion, head-up tilt, and interruption of the renin-angiotensin axis with the angiotensin converting enzyme inhibitor (ACEI) enalaprilat; and (5) in the supine position during ANP infusion and ACEI. Infusion of ANP in the supine posture significantly increased urine flow rate and sodium excretion compared to baseline while mean arterial pressure and plasma renin activity were unchanged. During head-up tilt and ANP infusion, urine flow rate and sodium excretion were no longer significantly elevated over baseline while mean arterial pressure decreased and plasma angiotensin II levels increased. Addition of ACEI caused a marked diminution of urine flow rate and sodium excretion compared to baseline levels despite continued ANP infusion. Although mean arterial pressure after ACEI administration was lower than baseline, it was not significantly different from the non-ACEI head-up tilt state. Placing subjects in the supine position during ANP infusion and ACEI administration increased mean arterial pressure to levels that were no longer different from baseline, but urine flow rate and sodium excretion remained significantly depressed to the same degree as during head-up tilt with ACEI.(ABSTRACT TRUNCATED AT 250 WORDS)
Grandis
D J
DJ
Department of Medicine, University of Pittsburgh, Pennsylvania.
Uretsky
B F
BF
Verbalis
J G
JG
Chong
T K
TK
Puschett
J B
JB
D000328:Adult; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D004231:Diuresis / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D009318:Natriuresis / Q000187:drug effects*; D011187:Posture; D012079:Renal Circulation / Q000187:drug effects; D012084:Renin-Angiotensin System / Q000187:drug effects*; D016683:Supine Position
D000806:Angiotensin-Converting Enzyme Inhibitors; D009320:Atrial Natriuretic Factor