Effects of volatile anesthetics on stiffness of mammalian ventricular muscle
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
Bethesda :Amer physiological soc
Journal of applied physiology / American Physiological Society. - Washington, D.C.
75th Clinical and Scientific Congress of the, International-Anesthesia-Research-Society, MAR 16-20, 2001, FT LAUDERDALE, FLORIDA
, p. 1563-1573
University of Antwerp
To assess the effects of halothane, isoflurane, and sevoflurane on cross bridges in intact cardiac muscle, electrically stimulated (0.25 Hz, 25 degreesC) right ventricular ferret papillary muscles (n = 14) were subjected to sinusoidal load oscillations (37-182 Hz, 0.2-0.5 mN peak to peak) at the instantaneous self-resonant frequency of the muscle-lever system. At resonance, stiffness is proportional to in * omega (2) (where in is equivalent moving mass and omega is angular frequency). Dynamic stiffness was derived by relating total stiffness to values of passive stiffness at each length during shortening and lengthening. Shortening amplitude and dynamic stiffness were decreased by halothane > isoflurane greater than or equal to sevoflurane. At equal peak shortening, dynamic stiffness was higher in halothane or isoflurane in high extracellular Ca2+ concentration than in control. Halothane and isoflurane increased passive stiffness. The decrease in dynamic stiffness and shortening results in part from direct effects of volatile anesthetics at the level of cross bridges. The increase in passive stiffness caused by halothane and isoflurane may reflect an effect on weakly bound cross bridges and/or an effect on passive elastic elements.