Five days after motor denervation, mammalian skeletal muscle sarcolemma undergoes a 50% decline in basal and catecholamine-stimulated adenylate cyclase activity. Sodium fluoride- and 5′-guanylyl imidophosphate [Gpp(NH)p)]-stimulated activities also are depressed. However, properties of the β-adrenergic receptor in the plasma membrane preparation of denervated muscle are similar to those of normal innervated muscle. The number and affinity of specific (-)-[3H]dihydroalprenolol binding sites, the effects of catecholaminergic ligands on binding (isoproterenol > epinephrine > norepinephrine), the stimulatory effects of Gpp(NH)p on adenylate cyclase activity, and the shift in concentration of catecholamines required to activate adenylate cyclase in the presence of Gpp(NH)p were similar in normal and denervated membranes. Thus denervation appears to uncouple the adenylate cyclase response from β-adrenergic stimulation primarily by a loss of adenylate cyclase activity with no change in receptor properties.
ASJC Scopus subject areas
- Developmental Neuroscience