MECHANICAL STIMULATION OF SKELETAL-MUSCLE CELLS MITIGATES GLUCOCORTICOID-INDUCED DECREASES IN PROSTAGLANDIN PRODUCTION AND PROSTAGLANDIN SYNTHASE ACTIVITY

The glucocorticoid dexamethasone (Dex) induces a decline in protein synthesis and protein content in tissue cultured, avian skeletal muscle cells, and this atrophy is attenuated by repetitive mechanical stretch. Since the prostaglandin synthesis inhibitor indomethacin mitigated this stretch attenuation of muscle atrophy, the effects of Dex and mechanical stretch on prostaglandin production and prostaglandin H synthase (PGHS) activity were examined. In static cultures, 10(-8) M Dex reduced PGF(2 alpha) production 55-65% and PGE(2) production 84-90% after 24-72 h of incubation. Repetitive 10% stretch-relaxations of non-Dex-treated cultures increased PCF2 alpha efflux 41% at 24 h and 276% at 72 h, and increased PGE(2) production 51% at 24 h and 236% at 72 h. Mechanical stimulation of Dex-treated cultures increased PGF(2 alpha) production 162% after 24 h, returning PGF(2 alpha), efflux to the revel of non-Dex-treated cultures. At 72 h, stretch increased PGF(2 alpha) efflux 65% in Dex-treated cultures. Mechanical stimulation of Dex-treated cultures also increased PGE(2) production at 24 h, but not at 72 h. Dex reduced PGHS activity in the muscle cultures by 70% after 8-24 h of incubation, and mechanical stimulation of the Dex-treated cultures increased PGHS activity by 98% after 24 h. Repetitive mechanical stimulation attenuates the catabolic effects of Dex on cultured skeletal muscle cells in part by mitigating the Dex-induced declines in PGHS activity and prostaglandin production. (C) 1994 Wiley-Liss, Inc.