title: Captopril-induced hypotension is inhibited by the bradykinin blocker HOE-140 in Na(+)-depleted marmosets.
abstract: Inhibition of angiotensin-converting enzyme (ACE) inhibits formation of angiotensin II and, by inhibition of kinin metabolism, may also increase vascular bradykinin. The present experiments were done in sodium-depleted, conscious, unrestrained marmosets (n = 5-11) to examine the contribution of bradykinin to ACE inhibitor-induced hypotension. Aortic blood pressure and heart rate (HR) were monitored via telemetry. After sodium depletion (low-sodium diet and furosemide), captopril (1 mg/kg po) caused a significant (P < 0.05) decrease in mean arterial blood pressure (MABP) (-34 +/- 3 mmHg, maximally, from 79 +/- 2 mmHg) but no change in HR compared with vehicle treatment. The bradykinin receptor antagonist HOE-140 (1 mg/kg sc) significantly inhibited the hypotensive response to captopril and caused marked tachycardia (+133 +/- 14 beats/min from 214 +/- 8 beats/min). HOE-140 (1 mg/kg sc) followed by vehicle administration had no effect on MABP but increased HR similarly. The hypotensive response to captopril was inhibited by HOE-140 regardless of the order of administration or the route of captopril administration (by mouth vs. subcutaneously). The hypotensive response to a renin inhibitor, A-72517 (3 mg/kg sc), was not inhibited by prior HOE-140 administration despite a similar HOE-140-induced tachycardia. These data suggest that the hypotensive effect of captopril in sodium-depleted, conscious marmosets is dependent on functional bradykinin B2 receptors. Also, blockade of B2 receptors uncovers marked tachycardia in this model, suggesting a tonic effect of bradykinin on control of HR in marmosets.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001920:Bradykinin / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D002144:Callithrix; D002216:Captopril / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D005260:Female; D007022:Hypotension / Q000139:chemically induced* / Q000503:physiopathology; D007279:Injections, Subcutaneous; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D012964:Sodium / Q000172:deficiency* / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D000092502:Renin Inhibitors
chemical_list: D001920:Bradykinin; D002216:Captopril; D010879:Piperazines; D012964:Sodium; D013844:Thiazoles; D000092502:Renin Inhibitors; C065679:icatibant; C076903:zankiren hydrochloride