Abstract
Abstract
This study was designed to investigate whether an infusion of atrial peptide is capable of modulating the hormonal and hemodynamic responses elicited by acute hemorrhage. Conscious dogs were bled at a rate of 0.8 ml·kg-1·min-1 until 20 ml of blood/kg body wt had been removed. Two experiments were performed on each dog; in one experiment the animal was given α-human atrial natriuretic peptide (α-hANP) (50 ng·kg-1·min-1) dissolved in saline; in the other only the saline vehicle was given. Right and left atrial pressures decreased during hemorrhage in all experiments; the absolute decreases were greater when the animals received atriopeptin, but the differences between treatments were statistically significant only for right atrial pressure. Cardiac output decreased (P < 0.05) and total peripheral resistance increased (P < 0.05) during hemorrhage when atriopeptin was infused; although these variables showed similar trends when vehicle alone was infused during hemorrhage, no significant changes occurred. Infusion of atrial peptide did not affect the decrease in arterial blood pressure that occurred during hemorrhage. The increase in plasma vasopressin induced by hemorrhage was potentiated, but the increase in plasma renin activity was attenuated when α-hANP was infused. Hemorrhage increased circulating aldosterone levels in each experiment, but the response was less pronounced when α-hANP was given during the experiment. Intravenous administration of α-hANP modulates the hemodynamic responses elicited by hemorrhage, potentiates the rise in plasma vasopressin, and attenuates the rise in plasma renin activity induced by acute blood loss in conscious dogs.
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