Selective hypersensitivity to bradykinin in salivary glands with ligated ducts

1. In submandibular salivary glands of cats in which the ducts have been tied for at least 3 days, the kallikrein activity of ;chorda' saliva is much reduced; but it is never absent, even after prolonged sympathetic stimulation.2. The relationship between the extent of the vasodilatation accompanying secretory activity and frequency of chorda stimulation is similar in normal glands and those with ducts ligated for 3 days, though, in the latter group, the variability is much greater.3. In glands of which the ducts have been tied for 3 days, the responses to close arterial injections of bradykinin are greatly increased, the dose-response curve being steeper and shifted to the left. This appears to be a selective increase in sensitivity, as the responses to the close arterial injections of ACh are, if anything, less than those in normal glands.4. In glands with ligated ducts, prolonged sympathetic stimulation reduces the vasodilatation following chorda stimulation.5. These results strengthen the conclusion that kinins participate in the vasodilatation accompanying glandular activity.