Inhibition of spinal afferent nerve-mediated gastric hyperemia by nicotine: role of ganglionic blockade.
The hypothesis that intravenous nicotine modulates gastric spinal afferent nerve function by its ganglionic-blocking property is tested. Stimulation of the gastric spinal afferent nerves in anesthetized rats is accomplished by intragastric capsaicin irrigation. Gastric blood flow is monitored by laser-Doppler flowmetry. The increase in gastric blood flow during intragastric capsaicin irrigation is significantly reduced by 4 and 40 micrograms.kg-1.min-1 of intravenous nicotine. The inhibition appears to be specific for the spinal afferent nerves as the increase in gastric blood flow induced by electrical stimulation of the vagal afferent nerves is unaltered by these doses of intravenous nicotine. A ganglionic-blocking dose (10 mg/kg) of intraperitoneal hexamethonium also significantly attenuates the gastric vasodilatory effect of intragastric capsaicin. Intravenous nicotine (40 micrograms.kg-1.min-1) combined with intraperitoneal hexamethonium (10 mg/kg) completely abolishes the gastric vasodilatory effect of intragastric capsaicin. These data suggest that intravenous nicotine offers a specific inhibition of the gastric spinal afferent nerve-mediated hyperemia, possibly as a consequence of its ganglionic-blocking property.
Leung
F W
FW
Research Service, Sepulveda Veterans Affairs Medical Center 91343.
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology*; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006940:Hyperemia / Q000209:etiology* / Q000503:physiopathology; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007834:Lasers; D008297:Male; D009475:Neurons, Afferent / Q000502:physiology*; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013270:Stomach / Q000098:blood supply* / Q000503:physiopathology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D006584:Hexamethonium Compounds; D018738:Hexamethonium; D009538:Nicotine; D002211:Capsaicin