Biphasic pulp blood-flow response to substance P in the dog as measured with a radiolabelled, microsphere injection method.
A dose of the vasoactive substance P (SP), affecting local circulation only (0.0001-0.001 micrograms/kg body weight) when given by a close injection into the maxillary artery, caused a biphasic flow response in pulpal blood flow (PBF), as measured by a radioisotope-labelled 15 micron microsphere injection technique. Immediately after the SP injection, PBF increased some 66 per cent (p less than 0.02) and vascular hindrance (Z) decreased to 40 per cent against control values (p less than 0.02), indicating vasodilation. Thirty seconds after the SP injection, PBF decreased by 53 per cent (p less than 0.05), and pulpal Z increased 139 per cent against control values (p less than 0.02), indicating decreased blood flow. This biphasic flow response may be due to the active vasodilation of arterioles by SP, which causes a compression of venules and hence a reduction of PBF in what is a low-compliance system.
Kim
S
S
Department of Endodontics, School of Dental and Oral Surgery, Columbia University, New York, NY 10032.
Dorscher-Kim
J
J
Liu
M T
MT
Trowbridge
H O
HO
D000818:Animals; D003037:Cobalt Radioisotopes; D003782:Dental Pulp / Q000098:blood supply*; D004285:Dogs; D005260:Female; D007267:Injections; D008297:Male; D008863:Microspheres; D011868:Radioisotopes; D012039:Regional Blood Flow / Q000187:drug effects; D012538:Scandium; D013373:Substance P / Q000494:pharmacology*
D003037:Cobalt Radioisotopes; D011868:Radioisotopes; D013373:Substance P; D012538:Scandium