Effects of Substance P on Blood Flow of the Dental Pulp in Dogs

Substance P (SP) is a known potent vasodilator (1, 2, 3). Olgart and his coworkers found SP-like immunoreactivity (SPLI) in nerves of the cat pulp suggesting the presence of SP (4). In addition, Gazelius and Olgart (5) demonstrated that electrical stimulation of the inferior alveolar nerve in cats caused a rapid increase in pulp blood flow which was followed by a prolonged reduction in pulp blood flow. The increase is thought to be mediated by SP released at the pulpal sensory nerve endings (6). However, administration of synthetic SP failed to increase pulp blood flow in cats; only when the vascular tone was elevated by electrical stimulation of the sympathetic nerve did the SP administration cause a pulp blood flow increase (5).