The relationship between glandular activity, bradykinin formation and functional vaso‐dilatation in the submandibular salivary gland

As a result of previous experiments on the submandibular salivary gland, it was concluded that functional hyperaemia in this organ is due to the vasodilator action of a material indistinguishable from bradykinin. This is formed in the interstitial fluid by the action on the plasma proteins of an enzyme-like substance escaping from the gland cells during activity (Hilton & Lewis, 1955a, b). In those experiments the enzyme was demonstrated in the effluent collected from the perfused gland activated by stimulation of the chorda tympani. In the present investigation we have examined the question whether this release is always obtained following glandular activity, no matter whether this is produced by chorda or sympathetic stimulation, or by injection of acetylcholine or sympathomimetic amines. The release ofbradykinin-forming enzyme from the perfused gland has been followed quantitatively, and the results show a consistent relationship between glandular activity, local vasodilatation and release of bradykinin-forming enzyme.