PURPOSE: Experimental investigation of the pharmacodynamic effects of propofol with and without simultaneous injections of dopamine or dobutamine in isolated hearts of rats. METHODS: In all animals under anaesthesia the hearts were removed and irrigated by a Krebs-Hensleit solution containing O2 (95%) and CO2 (5%), under constant pressure of 90 cm H2O and at 37ºC. After stabilization of the heart activity during 15 minutes, the control values were obtained. The following groups were considered: Group I (control) - 10 hearts perfused only with the Krebs-Hensleit solution during 11 minutes after the control values registration. Group II (dopamine-propofol-dopamine) -10 hearts with the following sequency of drug injections and results values registration: dopamine (50 mcg/ml), 1.3 and 5 minutes registration; propofol (25 mcg/ml), 1 minute period registration; dopamine again in the same dosis, 1.3 and 5 minutes values registration. Group III (dobutamine-propofol-dobutamine) -10 hearts with the following sequency of drug injections and results values registration: dobutamine (50 mcg/ml), 1.3 and 5 minutes registration: propofol (25 mcg/ml), 1 minute period registration; dobutamine again in the same dose and 1.3 and 5 minutes of registration. RESULTS: In Group I hearts, the dT/dt mean values changed only from 39.57 ± 3.97 to 39.37 ± 3.44 g.seg-1 (p>0.05). In Group II after propofol and dopamine the dT/dt fell 17.61 % (p<0.05) in the 1 min; 8.37% (p<0.05) in the 3rd min and 10.84% (p<0.05) in 5 th min, when compared with the results from isolated dopamine injections. In Group III the dT/dt increased 6.16% (p>0.050) in the 1 st min; 3.62% (p<0.05) in 3rd min and 3.08% (p>0.05) in the 5th min, over the values from isolated dobutamine injections. CONCLUSIONS: The myocardial contractile response to dopamine (50 mcg-ml-1) was partially inhibited; by propofol (25 mcg/ml-1) action was not altered.
Myocardial contraction; Propofol; Dopamine; Dobutamine; Rats