Negative Inotropic and Chronotropic Effects of Oxytocin

• DOI: 10.1161/01.hyp.38.2.292
• Publication Date: 2012-06-12T00:25:31Z
• Authors: Suhayla Mukaddam-...; Ya-Lin Yin; Josée Roy; Jolanta Gutkowska; René Cardinal
• Keywords: Oxytocin receptor

Abstract— We have previously shown that oxytocin receptors are present in the heart and perfusion of isolated rat hearts with results decreased cardiac flow rate bradycardia. The mechanisms involved negative inotropic chronotropic effects were investigated dog right atria absence central mechanisms. Perfusion through sinus node artery 10 −6 mol/L over 5 minutes (8 mL/min) significantly both beating (−14.7±4.9% basal levels, n=5, P <0.004) force contraction (−52.4±9.1% <0.001). Co-perfusion receptor antagonist (n=3) completely inhibited on frequency ( <0.04) <0.004), indicating specificity. also totally by co-perfusion 5×10 −8 tetrodotoxin <0.02) or atropine <0.03) but not hexamethonium, which implies these neurally mediated, primarily intrinsic parasympathetic postganglionic neurons. NO synthase inhibitor (L-NAME) (−1.85±1.27% versus −14.7±4.9% alone, <0.05) (−24.9±4.4% −52.4±9.1% n=4, <0.04). effect contractility was further L-NAME at −4 (−8.1±1.8%, <0.01). These studies imply mediated cholinergic neurons actions.