Cardiac rate, myocardial tension, coronary flow and myocardial contractility (dT/dt) variantions were registered in a population of fourty Wistar rats. In all animals, after ether anesthesia, the hearts were removed and perfused with 95% O2 and 5% CO2 enriched Krebs-Henseleit (K-H) solution, under 90 cm H2O constant pressure and temperature of 37,0 ± 0.5ºC, until complete stabilization, for control values registration. The hearts were distributed into four groups: Group I were perfused with K-H solution, gathering the data of cardiac performance after 1, 3, 5,10,15, 20, 25, and 30 minutes. In the other three groups, these data were also registered in the same times, after they were treated with 50 mcg of diazepam (Group II), 25 mcg of midazolam (Group III) and 25 mcg followed by 50 mcg of propofol (Group IV25 and IV50). The cardiac rate underwent significant variation in the groups estudied except Group II. Myocardial tension varied to a negative degree in the groups, except for Groups I and IV (propofol 50 mcg). In relation to myocardial contractility (dT/dt), except Group I, all groups underwent decreases. The coronary flow exhibited decreases in all groups studied. The observed variations were statistically significant (p<0.05). It is concluded that the drugs tested (diazepam, midazolama and propofol) determine statistically significant decrease of the myocardial contractility, without difference concerning the intensity of depression degree among all studied groups.
Diazepan in myocardial contractility; Midazolam in myocardial contractility; Propofol in myocardial contractility; Myocardial contractility