Dispersed rat parotid acinar cells. II. Characterization of adrenergic receptors.

The in vitro characterization of adrenergic receptors in isolated rat parotid acinar cells was accomplished through investigations of the transmembrane influxes of K and of the secretion of amylase in response to interactions of the cells with selected agonists and antagonists. Interaction of epinephrine (EPI) at concentrations of 10(-3)-10(-9) M with the alpha-adrenergic receptors resulted in rapid efflux of K from the cells. This effect was inhibited by phentolamine but not by propranolol or atropine. The process of secretion of amylase by these cells involved the activation of the beta-adrenergic receptors by the adrenergic agonists DL-isoproterenol (IPR) and EPI at similar to above concentrations. The interaction of these agonists with the beta receptors was inhibited by propranolol but not by phentolamine or atropine. Dibutyryl clclic AMP stimulated secretion of amylase at concentrations of 10(-8) M. A progressive increase in the secretory response of the cells was observed with increases in the dibutyryl cyclic AMP concentrations up to 10(-5) M. This effect was not inhibited by propranolol. This study demonstrates that dispersed rat parotid acinar cells have functionally intact adrenergic receptors and could be used as experimental tools for the studies of receptor physiology and pharmacology as well as other aspects of secretion at the cellular level.