Myocardial effects of propofol in hamsters with hypertrophic cardiomyopathy.

BACKGROUND

Propofol is a short-acting intravenous induction agent that induces cardiovascular depression but without significant effect on intrinsic myocardial contractility in various species. However, its effects on diseased myocardium remain unknown.

METHODS

The effects of propofol (1, 3, and 10 micrograms.ml-1) on the intrinsic contractility of left ventricular papillary muscles from normal hamsters and those with hypertrophic cardiomyopathy (strain BIO 14.6, aged 6 months) were investigated in vitro (Krebs-Henseleit solution, 29 degrees C, pH 7.40, Ca++ 2.5 mmol.l-1, stimulation frequency 3/min).

RESULTS

Cardiac hypertrophy (143 +/- 13%, P < 0.001) was observed in cardiomyopathic hamsters. The contractility of papillary muscles from hamsters with cardiomyopathy was less than that of controls, as shown by the decrease in maximum shortening velocity (-29%, P < 0.03) and active isometric force (-51%, P < 0.001). Propofol did not induce any significant effect on contraction, relaxation, and contraction-relaxation coupling under low and high loads in normal hamsters. The effects of propofol were not significantly different between normal hamsters and those with cardiomyopathy. A slight but significant increase in maximum unloaded shortening velocity was observed in cardiomyopathic hamsters at 3 micrograms.ml-1 (4 +/- 6%, P < 0.05) and 10 micrograms.ml-1 (7 +/- 6%, P < 0.05).

CONCLUSIONS

Propofol did not modify intrinsic myocardial contractility in normal hamsters, and no significant differences were observed between normal and cardiomyopathic hamsters. These results may be useful because, unlike propofol, most anesthetics decrease myocardial contractility. Nevertheless, indirect cardiac effects of propofol may be more important than its direct cardiac effects in patients with impaired cardiac function.