Effects of halothane, isoflurane, sevoflurane and desflurane on contraction of ventricular myocytes from streptozotocin-induced diabetic rats

Various clinically used volatile general anaesthetics (e.g. sevoflurane, halothane, isoflurane and desflurane) have been shown to have significant negative inotropic effects on normal ventricular muscle. However, little is known about their effects in ventricular tissue from diabetic animals. Streptozotocin (STZ)-induced diabetes is known to induce changes in the amplitude and time course of shortening and one report suggests that the inotropic effects of anaesthetics are ameliorated in papillary muscles from diabetic animals. The aim of these studies was to investigate this further in electrically stimulated (1 Hz) ventricular myocytes. Cells were superfused with either normal Tyrode (NT) solution or NT containing anaesthetic (1 mM) for a period of 2 min (at 30-32 degrees C). Myocytes from STZ rats were shown to have a significantly longer time to peak shortening (p > 0.001, n = 50) and the amplitude of shortening tended to be greater but this was not significant (p = 0.13, n = 50). Halothane, isoflurane, desflurane and sevoflurane significantly (p < 0.05) reduced the magnitude of shortening of control cells by 72.5 +/- 3.2%, 46.5 +/- 9.7%, 28.9 +/- 4.3% and 22.8 +/- 5.6%, respectively (n > 11 per group) but their steady-state negative inotropic effect was found to be no different in cells from STZ-treated rats (73.0 +/- 4.8%, 40.7 +/- 4.7%, 25.0 +/- 5.2% and 19.8 +/- 5.2%, respectively, n > 10 per group). Therefore, we conclude that the inotropic effects of volatile anaesthetics were not altered by STZ treatment.