Regulation of salivary kallikrein secretion in submandibular gland.

Unstimulated pairs of rat submandibular glands were compared with regard to their wet weight, total protein content and kallikrein antigenic activity. Paired glands from the same animal were found to be comparable, whereas differences from one animal to another were considerable. One of two paired glands was extirpated and used as control, and the other was subsequently subjected to stimulation. Salivary secretion was induced parasympathomimetically (intraperitoneal injections of pilocarpine; perfusion with acetylcholine and electrical stimulation of the ductal nerve plexus near the gland hilus) or sympathomimetically (cervical sympathetic nerve stimulation with or without administration of alpha- or beta-adrenergic blocker; perfusion with epinephrine, norepinephrine or isoproterenol). The effect was studied by measuring the change in total gland kallikrein content and by quantitation of kallikrein in saliva. A small secretion of kallikrein was always observed. However, alpha-adrenergic stimulation was 40 and 1 500 fold more effective in releasing kallikrein than beta-adrenergic and parasympathomimetic stimulation, respectively. Also, significantly more kallikrein was released by beta-adrenergic than parasympathomimetic stimulation. Immunohistochemistry confirmed the observed depletion of kallikrein following alpha-adrenergic stimulation. No alteration in kallikrein localization was observed in stimulated glands.