Alpha 1-adrenergic inhibition of protein synthesis in rat submandibular cells

The incorporation of [14C]leucine into protein in dispersed cells from rat submandibular gland was inhibited by epinephrine. The dose required for a half-maximal effect was approximately 10(-6) M. This sensitivity is similar to that of mucin and potassium secretion induced by epinephrine from these cells. The inhibitory effect of epinephrine was mediated by the activation of alpha 1-adrenergic receptors and was partially independent of extracellular calcium. The calcium ionophore A23187 also decreased protein synthesis in the presence and absence of extracellular calcium. Epinephrine diminished alpha-[14C]aminoisobutyric acid (AIB) influx, but the extent of altered AIB uptake was much less than the extent of decrease in protein synthesis. Analysis of newly synthesized protein by gel electrophoresis and autofluorography showed that epinephrine selectively inhibited the synthesis of specific submandibular proteins. In aggregate these results suggest that activation of alpha 1-adrenergic receptors in rat submandibular cells influences the regulation of protein synthesis by a mechanism that uses intracellular calcium.