Nicotine activation of neuronal nitric oxide synthase and guanylyl cyclase in the medulla increases blood flow of the common carotid artery in cats.
Individual activation of nicotinic acetylcholine receptor (nAChR) or nitric oxide (NO) synthase in the dorsal facial area (DFA) increases blood flow of common carotid artery (CCA) supplying intra- and extra-cranial tissues. We investigated whether the activation of nAChR initiated the activation of NO synthase and guanylyl cyclase to increase CCA blood flow in anesthetized cats. Microinjections of nicotine (a non-selective nAChR agonist), or choline (a selective α7-nAChR agonist) in the DFA produced increases in CCA blood flow ipsilaterally. These increases were significantly reduced by pretreatment with NG-nitro-arginine methyl ester (l-NAME, a non-specific NO synthase inhibitor), 7-nitroindazole (7-NI, a relatively selective neuronal NO synthase inhibitor) or methylene blue (MB, a guanylyl cyclase inhibitor) but not by that with N5-(1-iminoethyl)-l-ornithine (l-NIO, a potent endothelial NO synthase inhibitor). Control microinjection with d-NAME (an isomer of l-NAME), artificial cerebrospinal fluid or DMSO (a solvent for 7-NI) did not affect resting CCA blood flow, nor did they affect nicotine- or choline-induced response. In conclusion, activation of nAChR, at least α7-nAChR, led to the activation of neuronal NO synthase and guanylyl cyclase in the DFA, which induced an increase in CCA blood flow.
Gong
Chi-Li
CL
Department of Physiology, School of Medicine, China Medical University and Hospital, Taichung, Taiwan.
Leung
Yuk-Man
YM
Huang
Yi-Ping
YP
Lin
Nai-Nu
NN
Hung
Yi-Wen
YW
Lee
Tony Jer-Fu
TJ
Kuo
Jon-Son
JS
D000818:Animals; D017536:Carotid Artery, Common / Q000187:drug effects / Q000502:physiology*; D002415:Cats; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006162:Guanylate Cyclase / Q000378:metabolism*; D008297:Male; D008526:Medulla Oblongata / Q000098:blood supply / Q000187:drug effects / Q000201:enzymology*; D008845:Microinjections / Q000379:methods; D009474:Neurons / Q000187:drug effects / Q000201:enzymology*; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D052248:Nitric Oxide Synthase Type I / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000502:physiology; D064569:alpha7 Nicotinic Acetylcholine Receptor
D018722:Nicotinic Agonists; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D009538:Nicotine; D052248:Nitric Oxide Synthase Type I; D006162:Guanylate Cyclase