Sialotonin: vasopressor substance in saliva and submandibular gland of the cat.

1. The large molecular pressor agent, sialotonin, present in cat saliva, has been separated from kallikrein and characterized further. 2. Sialotonin is present in saliva produced by parasympathetic (ch8da) but not in that produced by sympathetic nerve stimulation. After degenerative preganglionic parasympathetic nerve section, both sialotonin and kallikrein disappear completely, or nearly so. Sympathetic nerve section, however, fails to affect the concentration of these substances in chorda saliva. 3. The sialotonin activity is saliva is unaffected by ligation of Wharton's duct for 3--4 days whereas the kallikrein concentration is greatly reduced. 4. Although normally present in chorda saliva, sialotonin cannot be detected in aqueous extracts of the submandibular gland. It is present, however, in extracts of glands which have previously been subjected to prolonged sympathetic nerve stimulation or to ligation of the duct for 3-4 days. 5. The intravenous or close-aterial injection of sialotonin causes marked but brief reductions of blood flow in the submaxillary gland and intestine.