Mechanisms of Negative Inotropy of Halothane, Enflurane and Isoflurane in Isolated Mammalian Ventricular Muscle
The volatile anesthetics halothane, enflurane, and isoflurane are potent myocardial depressants. They cause a concentration-dependent negative inotropic effect in humans, experimental animals, and in cardiac tissues isolated from a variety of mammalian species.1 Their negative inotropic effect has been attributed to interference with 1) transsarcolemmal Ca2+ influx; 2) Ca2+ uptake and release from the sarcoplasmic reticulum; and 3) Ca2+ sensitivity of the contractile proteins. The purpose of this communication is to review the relative importance of the decrease in intracellular Ca2+ availability and of the decrease in myofibrillar Ca2+ sensitivity brought about by these anesthetics. Our conclusions will be illustrated by recent studies in intact ventricular muscle, i.e., the right ventricular papillary muscle of the ferret.
KeywordsSarcoplasmic Reticulum Papillary Muscle Volatile Anesthetic Negative Inotropic Effect Force Trace
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