calcimycin and Contracture

The results are reported of the contracture test obtained by using the calcium ionophore A 23187 (Calcimycin) in two patients, the son (A) and the mother (B). The past history of patient A revealed the occurrence of an impending malignant hyperthermia crisis during induction of anaesthesia in 1975. The A 23187 contracture test confirmed the presence of the malignant hyperthermia trait in patient A, whose muscle biopsy had been submitted to the caffeine contracture test, according to Ellis' technique, and found to be positive in the presence of 1 mmol of caffeine in the tissue bath; the contracture test could not be completed with a halothane contracture test, due to the impaired viability of the muscle fibres obtained. On the reverse, the mother (patient B) was found to be negative to the tests applied: the caffeine contracture test, the halothane contracture test and the contracture test performed with the calcium ionophore A 23187. It is suggested the A 23187 contracture test be added to the contracture tests as defined by the European Malignant Hyperpyrexia Group. This test could be of great help in identifying the percentage of relatives of MHS ("malignant hyperthermia susceptible") patients found to be MHE ("malignant hyperthermia equivocal").

Topics: Adolescent; Adult; Caffeine; Calcimycin; Contracture; Female; Halothane; Humans; Male; Malignant Hyperthermia; Muscles

Ovalbumin (OA) and the calcium ionophore A23187 induced a dose-dependent contraction of guinea pig tracheal strips. The OA-induced contraction (of sensitized trachea) consisted of an initial peak concentration, maximal between 5 and 10 min, followed by a very gradual decline from the peak. On the other hand, A23187 induced a sustained contraction of the trachea with a more gradual onset. Both antigen- and A23187-induced contractions required the presence of extracellular calcium. The response was not reduced by delaying (up to 10 min) the addition of calcium, suggesting that the mechanism of antigen-induced contraction differs from that of antigen-induced histamine secretion from rat mast cells and human basophils. The 1st min of the OA-induced contraction was inhibited significantly by mepyramine (10(-5) M) suggesting that histamine contributed to the contraction at this time point. In contrast, A23187-induced contraction was unaffected by mepyramine. On the other hand, both the A23187-induced contraction and the prolonged phase of the OA-induced contraction were enhanced by indomethacin, a cyclooxygenase inhibitor, and inhibited by phenidone, a cyclooxygenase-lipoxygenase inhibitor. This suggests that a product of the lipoxygenase pathway of arachidonic acid metabolism contributes to OA- and A23187-induced contraction of the guinea pig trachea.

Topics: Animals; Anti-Bacterial Agents; Antigens; Calcimycin; Calcium; Contracture; Guinea Pigs; Indomethacin; Male; Ovalbumin; Pyrazoles; Pyrilamine; Time Factors; Trachea