engleski

Beta-adrenergic stimulation of compensatory adrenal growth: do beta-2 receptors participate?

We have already reported that adrenergic stimulation of compensatory adrenal growth induced by unilateral adrenalectomy involves beta1-adrenoceptors and that the receptors change their signaling mechanism from stimulation to inhibition of adenylyl cyclase (Soc Neurosci Abs 1996; 22:1592). To investigate possible involvement of beta2- receptors, we studied the effects of beta2 agonist and antagonists in female Wistar rats. As measured 10 days after the operation, adrenal wet weight, protein and total RNA and DNA contents were increased, indicating compensatory growth. The observed increase was dose-dependently abolished by butoxamine, a beta1-selective antagonist. In addition, the inhibitory effect of guanethidine-induced sympathectomy on compensatory growth was antagonized by both the non-selective beta-adrenergic agonist isoproterenol and the beta1-selective salbutamol. In another type of experiments, 10 days after adrenalectomy cortices were incubated with either isproterenol (100 uM) alone or both isoproterenol and butoxamine (50 to 200 uM). Tissue concentrations of cAMP were measured as an indicator of adenylyl cyclase singling system activity. The isoproterenod-induced decrease of cAMP concentrations was dose-dependently antagonized by butoxamine. These results indicate that adrenergic stimulation of compensatory adrenal growth beside beta1 receptors also includes beta2 receptors.

adrenal gland; compensatory growth; beta2-adrenergic receptors; adenylyl cyclase

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