| Abstract: | Multiple injections of dobutamine, a selective adrenergic beta-1 receptor agonist, or isoproterenol, a nonselective beta receptor agonist, produced significant dose-dependent enlargement of the submandibular glands of male rats. The glandular enlargement induced by dobutamine or isoproterenol was characterized by significant increases in glandular protein and nucleic acid content and a marked increase in the RNA/DNA ratio. Metoprolol, a selective beta-1 receptor antagonist, significantly inhibited the glandular enlargement induced by dobutamine or isoproterenol and produced a parallel shift in the isoproterenol dose-response curve. Metoprolol also inhibited the increased protein and nucleic acid content induced by dobutamine or isoproterenol. Multiple injections of selective adrenergic beta-2 receptor agonists, terbutaline, fenoterol or salmefamole, failed to produce submandibular gland enlargement. These results indicate that adrenergic beta-1 receptors mediate submandibular gland hypertrophy in the rat. |
