A study of the capacity of various eicosanoids to stimulate skeletal muscle formation in chicken embryos.

Inhibitors of prostaglandin synthetase decrease the number of fibres in chicken embryo skeletal muscles (McLennan, 1987a), raising the possibility that muscle formation may be capable of being stimulated by an eicosanoid (prostaglandins, leukotrienes and related substances). This hypothesis has been examined by determining the effect of various prostaglandins and related drugs on fibre formation in vivo. Of the eicosanoids tested, only the E and I series PGs altered muscle formation. PGE2 decreased the number of fibres whereas 16,16-dimethylPGE2 increased fibre formation. Tranylcypromine (TR), an inhibitor of PGI2 formation, decreased fibre formation and PGI2 reversed the action of TR. Fibre numbers were unaffected by A, D and F alpha series prostaglandins, a thromboxane agonist and a lipoxygenase inhibitor. The mechanism by which E and I series prostaglandins exert their effect on chicken embryos remains to be determined but the possibility that a PGE antagonist or PGI2 antagonist may be used to stimulate muscle formation is worthy of further examination.