Key result
Atriopeptin III (10 micrograms/kg i.v.) decreased cardiac output, stroke volume, and mean arterial pressure in rats, but did not alter cardiac performance curves.
Why the study?
Does atriopeptin III alter cardiac performance in anaesthetized rats?
Does atriopeptin III alter cardiac performance in anaesthetized rats?
Atriopeptin III decreases mean arterial pressure and cardiac output in rats without exerting a negative myocardial inotropic effect.
Atriopeptin III may lower pressure and output via preload without inotropy in rats; leaves open translation to other species or conscious models.
The effects of atriopeptin III (APIII) on systemic haemodynamics were examined in 12 anaesthetized rats. Five minutes following intravenous injection (i.v.) of 10 micrograms/kg APIII, cardiac output CO, measured by electromagnetic flowmetry, stroke volume and mean arterial pressure (MAP) decreased by 14, 13 and 8% (P less than 0.05), respectively, and total peripheral resistance (TPR) increased by 10% (P less than 0.05). Heart rate (HR) and left ventricular end-diastolic pressure (LVEDP) did not change. In order to examine cardiac performance, whole blood was infused into three groups of 12 rats each receiving either no injection, APIII (10 micrograms/kg i.v.) or APIII (10 micrograms/kg i.v.) plus a continuous infusion of phenylephrine to increase MAP to pre-injection levels. Cardiac performance curves did not differ among the three groups. These data indicate that the immediate decreases in MAP and CO produced in rats by a maximum natriuretic bolus dose of APIII were not mediated by a negative myocardial inotropic effect.
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Natsume et al. (1986) studied this question. Atriopeptin III (APIII) vs. No injection was evaluated on Cardiac performance curves. Atriopeptin III (10 micrograms/kg i.v.) decreased cardiac output, stroke volume, and mean arterial pressure in rats, but did not alter cardiac performance curves.
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