Somatosensory afferents in the parasympathetic vasodilator reflex in cat lip.
Somato-parasympathetic reflexive vasodilatation elicited by activation of the nociceptors in the oro-facial areas of the cat was investigated. Changes in lower lip blood flow monitored by a laser Doppler flowmeter took place in pentobarbital-anesthetized and artificially respirated cats. Pinch and heat stimulation of the oro-facial areas evoked a blood flow increase similar to that of electrically induced vasodilatation. Sustained increased responses in blood flow were obtained when a 1% capsaicin solution was applied to the tongue. These results show that the C-polymodal nociceptor is a strong candidate for a receptor that provokes somato-parasympathetic vasodilatation. Capsaicin-insensitive nerve fibers, however, also participate because electrical stimulation of the capsaicin-treated tongue evoked vasodilatation. The correlation between noxious stimulation-induced vasodilatation and systemic blood pressure change also is discussed.
Karita
K
K
Department of Physiology, Tohoku University School of Dentistry, Sendai, Japan.
Izumi
H
H
D000818:Animals; D001794:Blood Pressure; D002211:Capsaicin / Q000494:pharmacology; D002415:Cats; D004558:Electric Stimulation; D006358:Hot Temperature; D008046:Lip / Q000098:blood supply / Q000294:innervation*; D009475:Neurons, Afferent; D009619:Nociceptors / Q000502:physiology*; D010275:Parasympathetic Nervous System / Q000502:physiology; D012018:Reflex / Q000502:physiology; D012039:Regional Blood Flow; D014664:Vasodilation / Q000187:drug effects*
D002211:Capsaicin