Direct Effects of Propofol on the Left Ventricular Papillary Muscles of Rats Compared with Other Intravenous Induction Agents

The isometric contractions of isolated rat myocardiums to propofol were compared with those to thiopental, etomidate, and brevital. 40 rat left ventricular papillary muscles were evenly divided into four groups and were exposed to the mean maximum post-induction plasma concentration and its double concentration in random order. Both concentrations of propofol showed 17.5% to 22.5% depression in Tpd, +dp / dt.nax, and -dp / dt.nax, which was the greatest among four agents, while thiopental revealed the least depression. Brevital and etomidate depressed three parameters to a similar degree. In Tr, 1FT, and RT90%, there were only negligible changes in all four drugs in both concentrations. We might say that the depression of myocardial contractility by propofol is, in part,a important cause of hypotension. Therefore propofol should be used with caution in patients with a depressed myocardial contractility