[The baroreflex component in the mechanism of the hypotensive action of atrial peptides].

Changes in the arterial pressure (AP), heart rate (HR) and sensitivity of chronotropic baroreceptor reflex (SBR) evoked by i. v. infusion of alpha-ANP, AP-III, AP-II, and AP-I (1 mg/kg/min) were studied in alert Wistar rats. The SBR was tested by infusion of phenylephrine or sodium nitroprusside. All the ANP analogues, except AP-1, were shown to decrease the AP and evoke differential changes in the SBR. The SBR evoked by phenylephrine was increased by 60-80%, whereas SBR evoked by sodium nitroprusside was decreased by 30-60%. The specific changes in tachycardic and bradycardic components of the baroreceptor reflex after ANP analogues infusions seem to reflect participation of the baroreceptor reflex in the mechanism of ANP-induced hypotension.