Anaesthesia
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Malignant hyperthermia is a dreaded complication of general anaesthesia. Predisposed individuals can be identified using the standardised caffeine/halothane in-vitro contracture test on a surgically dissected skeletal muscle specimen. Skeletal muscle is composed of muscle fibres and interwoven fascial components. ⋯ Using immunohistochemical staining, α-smooth muscle actin-positive cells (myofibroblasts) were detected in the epi-, endo- and perimysium of human fascial tissue. Force measurements on isolated fascial strips after pharmacological challenge with mepyramin revealed that myofascial tissue is actively regulated by myofibroblasts, thereby influencing the biomechanical properties of skeletal muscle. Absence of electrical reactivity and insensitivity to caffeine and halothane suggests that, reassuringly, the malignant hyperthermia diagnostic in-vitro contracture test is not influenced by the muscular fascial tissue.