Effects on rat parotid amylase and Ca of alpha- and beta-adrenergic sympathetic stimulation

The roles of alpha- and beta-adrenergic receptors in the regulation of the secretion of amylase and calcium from rat parotid gland were studied by using direct electrical stimulation of the sympathetic innervation to the gland in the presence of selective adrenergic blocking agents. When phenoxybenzamine was administered intraperitoneally 25 min prior to nerve stimulation, the highest [Ca] (12-14 meq/liter) and amylase activity (1,000 mg/microliter) in the evoked saliva were observed. On the other hand, stimulation of the nerve in the presence of propranolol evoked a saliva that contained the lowest [Ca] (5-6 meq/liter) and amylase activity (170 mg/microliter). Furthermore, salivary flow (4.27 +/- 0.42 microliter/min X g) induced by sympathetic nerve stimulation in the presence of phenoxybenzamine was higher than that induced by sympathetic nerve stimulation in the presence of propranolol (2.55 +/- 0.39 microliter/min X g). Therefore, it was concluded that beta-adrenergic receptors play the major role in the regulation of salivary flow and the secretion of amylase and calcium, whereas alpha-adrenergic receptors play a minor role in the regulation of these parameters.