Desflurane Induces Only Minor Ca2+ Release from the Sarcoplasmic Reticulum of Mammalian Skeletal Muscle

Background: Desflurane is a weaker trigger of malignant hyperthermia than is halothane. There are very few data of the pathophysiologic background of this observation. Therefore, the authors' aim was to investigate the direct effect of desflurane on calcium release in skinned skeletal muscle fibers.

Methods: For the measurements, single saponin-skinned muscle fiber preparations of BALB/c mice were used. For Ca2+ release experiments, liquid desflurane at 0.6 and 3.5 mm was applied to weakly calcium-buffered solutions with no added Ca2+. Desflurane was diluted in strongly Ca2+-buffered solutions, with Ca2+] between 3.0 and 24.9 mu]m for Ca2+]-force relations. Force transients were transformed into Ca2+ transients based on the individual Ca2+]-force relations. As controls, 30 mm caffeine and equimolar sevoflurane were investigated in the same muscle fibers.

Results: At 3.5 mm, desflurane induced peak force transients of 8 +/- 4% (mean +/- SD) of maximal Ca2+-activated force (Tmax). These peak values were significantly smaller than those in the presence of 3.5 mm sevoflurane (24 +/- 10% of Tmax, P < 0.05), and 4 or 5 times smaller than previously reported Ca2+-release-induced force transients by equimolar halothane. Calculated peak Ca2+ transients derived from force transients and induced by 3.5 and 0.6 mm desflurane were significantly smaller than those induced by 30 mm caffeine. The Ca2+]-force relation was shifted by desflurane, resulting in a Ca2+-sensitizing effect. The maximal Ca2+-activated force was significantly increased by 0.6 mm desflurane in comparison with the control, with no added substance (P <= 0.05).