β-Adrenergic agonist-sensitive adenylate cyclase activity and binding of the β-adrenergic antagonist (-)-[125I]iodopindolol were studied in rat liver during development of male Fischer 344 rats ages 6-60 days. In liver homogenates maximum adenylate cyclase response to β-adrenergic agonist (10-5 M isoproterenol or epinephrine) decreased by 73% (P < 0.01) between 6 and 60 days, with most of the decrease (56%; P < 0.001) occurring by 20 days. β-Adrenergic receptor density (B(max)) showed a corresponding decrease of 66% (P < 0.01) by 20 days without subsequent change. Binding characteristics of stereospecificity, pharmacological specificity, saturability with time, and reversibility were unchanged with age. GTP-, fluoride-, forskolin-, and Mn2+-stimulated adenylate cyclase activities also decreased during development, suggesting a decrease of activity of the catalytic component and/or guanine nucleotide regulatory component of adenylate cyclase. These results indicate that the developmental decrease of β-adrenergic agonist-sensitive adenylate cyclase activity may result from decreased numbers of β-adrenergic receptors. Developmental alterations of nonreceptor components of the enzyme may also contribute to changes of catecholamine-sensitive adenylate cyclase.
|Original language||English (US)|
|Journal||American Journal of Physiology - Endocrinology and Metabolism|
|State||Published - 1985|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Physiology (medical)