The stimulation of protein degradation in muscle by Ca2+ is mediated by prostaglandin E2 and does not require the calcium-activated protease.

摘要: Treatment of isolated rat skeletal muscles with the Ca2+ ionophores, A23187 or ionomycin, increased overall protein degradation 45-140%. Removal extracellular reduced proteolysis and most stimulation by A23187. sulfhydryl inhibitor, mersalyl, completely inactivated Ca2+-activated protease without altering breakdown This agent did not inhibit lysosomal protease, cathepsin B, in muscle; however, leupeptin Ep-475, which this enzyme intact cells, decreased Ca2+. Thus, effect does require enzyme, but seems to involve proteases. Prostaglandin E2 (PGE2) its precursor arachidonic acid, were previously shown stimulate muscle through an on function. We tested whether enhancement ionophores may result from synthesis PGE2. release PGE2 PGF2 alpha 3-4-fold. High potassium also markedly promotes proteolysis, apparently increasing intracellular Ca2+, treatment stimulates prostaglandin production. Indomethacin aspirin, cyclooxygenase, mepacrine, inhibits phospholipase A2, increase These agents high K+. appears promote stimulating PGE2, turn activates apparatus.