Beta-Adrenergic Stimulation of Cyclic AMP Content and Parathyroid Hormone Release from Isolated Bovine Parathyroid Cells**

Abstract

The effects of .beta.-adrenergic agonists and antagonists on cyclic[c]AMP accumulation and parathyroid hormone (PTH) release from isolated bovine parathyroid cells were determined. .beta.-adrenergic agonists markedly stimulate cAMP production and PTH release with an order of potency (-)isoproterenol > (-)epinephrine > > (-) norepinephrine, suggesting a .beta.2-type adrenergically mediated process. Both effects are blocked by the .beta.-blocker propranolol with the strict stereospecificity expected for a .beta.-adrenergic response. Low Ca concentrations also stimulate cAMP accumulation, but the cyclic nucleotide response under these conditions is only 3% of that obtained with isoproterenol, raising the possibility that factors other than cAMP may control low Ca-mediated PTH release. The release of PTH by low Ca is also not blocked by propranolol, confirming the independence of the response to low ambient Ca from the .beta.-adrenergic receptor. These studies substantiate further the utility of the isolated parathyroid cell preparation for studying secretagogue-mediated alterations in cyclic nucleotides and hormone secretion. Isolated cells also make feasible the direct identification of .beta.-adrenergic receptors in parathyroid cell membranes and whole cells.