Cardiovascular and renal effects of iso-rANP, a second natriuretic peptide from rat atria.
Administration of a newly discovered second atrial peptide, iso-atrial natriuretic peptide (or iso-rANP(1-45) for the rat), caused hypotension, decreased heart rate, diuresis, and increased renal excretion of Na+, K+, and Cl- in the anesthetized rat. Bolus injections of chemically synthetic iso-rANP(1-45) had circulatory and diuretic activity equal to or greater than rANP(99-126) but, at low doses, a lesser effect on renal electrolyte excretion. The synthetic peptide fragment, iso-rANP(17-45), analogous in structure to rANP(99-126), had attenuated activity on the circulation, and at low doses, attenuated activity on the kidney. At higher doses, where renal responses to rANP(99-126) were less (downside of a biphasic response), both iso-rANP(1-45) and (17-45) had greater effects on water and electrolyte excretion than rANP(99-126). Injections of iso-rANP(1-45) and (17-45) increased hematocrit, whereas rANP(99-126) did not; furthermore, unlike rANP(99-126), iso-rANP did not affect arterial plasma Na+ concentration. The heart produces at least two genetically different atrial natriuretic peptides which affect the circulation and salt and water balance.
Jennings
D B
DB
Department of Physiology, Queen's University, Kingston, Ont., Canada.
Flynn
T G
TG
D000595:Amino Acid Sequence; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D004573:Electrolytes / Q000097:blood; D006439:Hemodynamics / Q000187:drug effects*; D007668:Kidney / Q000187:drug effects*; D008297:Male; D008969:Molecular Sequence Data; D009318:Natriuresis / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains
D004573:Electrolytes; C062794:iso-atrial natriuretic peptide; D009320:Atrial Natriuretic Factor