Circulatory and metabolic responses in awake dogs to infusion of iso-rANP/(rBNP).
We reported that a second rat atrial peptide, iso-atrial natriuretic peptide (iso-rANP(1-45)) and a potential putative homologue, iso-rANP(17-45) (identical with rat brain natriuretic peptide except for one amino acid) elicited circulatory and renal responses in anesthetized rats. In the present studies, low-dose intravenous infusions of iso-rANP(1-45) (6.3-25 pmol kg-1 min-1) and iso-rANP(17-45) (12.5-50 pmol kg-1 min-1) into conscious dogs produced subtle circulatory effects compared to control studies. Relative to oxygen consumption, cardiac output was lower and total peripheral resistance higher with both iso-rANP(1-45) and iso-rANP(17-45). Heart rate tended to be slightly lower relative to control studies during peptide infusions, and the highest infusion doses caused a decrease in mean arterial pressure. Plasma protein increased and plasma osmolality decreased with iso-rANP(1-45); infusion of iso-rANP(17-45) caused a decrease in the respiratory exchange ratio. The mechanism of action of iso-rANP may have been direct, via an active receptor. However, we previously reported for these same experiments that infusion of iso-rANP(1-45) and iso-rANP(17-45) increased plasma ANP and decreased plasma renin activity. Thus, circulatory changes during infusion of iso-rANP were consistent with an indirect mechanism related to increased endogenous ANP.
McKirdy
J C
JC
Department of Physiology, Queen's University, Kingston, Canada.
Ohtake
P J
PJ
Flynn
T G
TG
Jennings
D B
DB
D000136:Acid-Base Equilibrium / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000008:administration & dosage / Q000494:pharmacology*; D002248:Carbon Monoxide / Q000378:metabolism; D004285:Dogs; D004573:Electrolytes / Q000097:blood; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D007275:Injections, Intravenous; D008297:Male; D008660:Metabolism / Q000187:drug effects*; D011498:Protein Precursors / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats
D004573:Electrolytes; D011498:Protein Precursors; C062794:iso-atrial natriuretic peptide; D002248:Carbon Monoxide; D009320:Atrial Natriuretic Factor