Central hemodynamic effects of an oxytocin receptor antagonist (atosiban) in the isolated, perfused rat heart

OBJECTIVE: Atosiban is a selective oxytocin receptor antagonist capable of inhibiting oxytocin-induced contractility of the uterus. Trials of this age nt in intact animals and women as a tocolytic agent for preterm labor have shown atosiban to be devoid of cardiac effects. This is in contrast to othe r tocolytic agents, which have profound hemodynamic effects. We conducted t his study to determine the cardiac effects of atosiban in the isolated, per fused vat heart model. METHODS: Hearts were excised from 60 female Sprague-Dawley rats and attache d to a Langendorff apparatus Left ventricular systolic pressure, heart rate , and contractility were measured. Hearts from half of che animals were exp osed serially to 300 mu g/min, 600 mu g/min, and 1200 mu g/min of atosiban. The remaining hearts formed the control group and were exposed to aerated Krebs solution. RESULTS: There were no significant differences between hearts exposed to at osiban and hearts within the control group for heart rate, left ventricular systolic pressure, and contractility. P values ranged from .12 to .73. CONCLUSIONS: Using a classic physiologic model to study cardiac performance and drug effects, we were unable to detect any central hermodynamic effect s of atosiban. This is in contrast iu oxytocin, which we Previously studied and found negative chronotropic and positive ionotropic effects. Copyright (C) 1999 by the Society for Gynecologic Investigation.