beta 1- and beta 2-adrenoceptor agonists have different effects on rat parotid acinar cells

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Abstract
To determine whether .beta.1- and .beta.2-adrenoceptors have similar functions in salivary glands, Sprague-Dawley rats were chronically treated with either the .beta.1-selective (prenalterol), .beta.2-selective (terbutaline) or nonselective .beta.-agonist isoproterenol. All 3 agonists increased parotid and submandibular gland weight and acinar cell size. Isoproterenol and prenalterol caused marked quantitative and qualitative alterations in the granule population, whereas terbutaline had no effect. A single injection of isoproterenol caused a significant amylase release and accumulation of cAMP. Prenaterol was as potent as isoproternol with regard to amylase release but was without effect on the cAMP content. In contrast, terbutaline had a minimal effect on amylase release but had the same effect as isoproterenol on cAMP accumulation. The in vitro perfusion experiments confirmed these in vivo results with respect to the effects of the selective .beta.-agonists. Thus, the present investigation using both morphological and biochemical methods suggests that .beta.1- and .beta.2-adrenoceptors may have different functions in rat parotid acinar cells. In addition, the stimulus-growth coupling seems to be unrelated to stimulus-secretion coupling.