Changes in expression of a functional Gi protein in cultured rat heart cells.

摘要: The muscarinic cholinergic agonist, carbachol, and pertussis toxin were used to examine the functional status of guanine nucleotide-binding protein that inhibits adenylate cyclase (G{sub i}) in cultured neonatal rat heart myocytes. isoproterenol stimulation activity myocyte membranes adenosine 3{prime},5{prime}-cyclic monophosphate (cAMP) accumulation intact cells (4 days culture) insensitive carbachol. However, for 11 days, carbachol inhibited isoproterenol-stimulated cAMP by 30%. Angiotensin II (ANG II) was also found inhibit day a dose-dependent manner. Pertussis treatment reversed inhibitory effects both ANG suggesting role G{sub i} process. Carbachol binding from 4 relatively nucleotides when compared with or adult cells. Furthermore, toxin-mediated {sup 32}P incorporation into 39- 41-kDa substrate increased 3.2-fold over measured membranes. These findings support view that, although is expressed, it nonfunctional 4-day-old myocytes acquisition dependent on culture conditions. Furthermore,more » receptor can couple heart.« less