Effects of volatile anesthetics on elastic stiffness in isometrically contracting ferret ventricular myocardium

Abstract

The effects of halothane, isoflurane, and sevoflurane on elastic stiffness, which reflects the degree of cross-bridge attachment, were studied in intact cardiac muscle. Electrically stimulated (0.25 Hz, 25°C), isometrically twitching right ventricular ferret papillary muscles ( n = 15) at optimal length ( L max) were subjected to sinusoidal length oscillations (40 Hz, 0.25– 0.50% of L maxpeak to peak). The amplitude and phase relationship with the resulting force oscillations was decomposed into elastic and viscous components of total stiffness in real time. Increasing extracellular Ca2+ concentration in the presence of anesthetics to produce peak force equal to control increased elastic stiffness during relaxation, which suggests a direct effect of halothane and sevoflurane on cross bridges.