Release of tonin and of kallikrein by perfused rat submaxillary gland.

The release of tonin and kallikrein was investigated in the venous effluent of the perfused rat submaxillary gland (SMG). The SMG was perfused through the common carotid artery after all branches except the SMG artery had been ligated. The venous outflow was collected from the SMG vein. The contralateral nonperfused gland was used as control. The infusion of isoproterenol increased tonin release without affecting its concentration in the SMG. Theophylline increases both tonin secretion and tonin concentration in the SMG. These results suggest that beta-adrenergic stimulation enhances tonin release by increasing synthesis in the SMG, and that these effects might be mediated by cAMP. The infusion of norepinephrine did not affect either tonin release or tonin concentration in the gland. Kallikrein release was significantly increased by norepinephrine, isoproterenol, and theophylline. However, whereas alpha-stimulation produced a significant decrease in kallikrein concentration in the stimulated SMG, beta-adrenergic and theophylline stimulation produced no significant changes in tissue kallikrein. These results suggest that alpha-adrenergic stimulation increases kallikrein release by depleting the enzyme from the gland, whereas beta-adrenergic stimulation might increase kallikrein release by stimulating its synthesis in the gland.