Enhancement effects of nicotine on neurogenic contractile responses in rabbit gastric fundus.
Nicotine, a nicotinic acetylcholine receptor agonist, plays a role in the modulation of neurotransmitter release following nerve stimulation in both the central and the peripheral nervous system. Nitric oxide and prostaglandins modulate the release of various neurotransmitters in different tissues. We aimed to investigate the effects of nicotine on neurogenic contractile responses via nicotinic acetylcholine receptors and, if a change occurred, to investigate the effects of N(W)-nitro-L-arginine methyl ester (L-NAME) and indomethacin on this change in rabbit gastric fundus. Electrical field stimulation (EFS)-evoked contractile responses were recorded from gastric fundus strips obtained from rabbits with an isometric force displacement transducer. Nicotine was applied to preparations at varying concentrations. Then, the effects of hexamethonium, cadmium (Cd(2+)), indomethacin, and L-NAME were tested on the EFS-evoked contractions in the presence of nicotine. Nicotine-induced transient neurogenic contractions in a dose-dependent manner. Cd(2+) and hexamethonium inhibited nicotine-induced transient neurogenic contractions, but indomethacin and L-NAME produced no effect. In conclusion, nicotine increased EFS-evoked contractile responses, possibly by facilitating neurotransmitter release from nerve terminals by a mechanism dependent on the influx of Ca(2+) from voltage-gated Ca(2+) channels via activation of nicotinic acetylcholine receptors in isolated rabbit gastric fundus. Endogenous nitric oxide and prostaglandins do not play a physiological role in the regulation of this neurotransmitter release.
Ilhan
Sevil Ozger
SO
Refik Saydam Hygiene Center Presidency, School of Public Health, Ankara, Turkey.
Vural
Ismail Mert
IM
Dileköz
Ergin
E
Oztürk
Gökçe Sevim
GS
Sarioglu
Yusuf
Y
D000818:Animals; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D005748:Gastric Fundus / Q000187:drug effects*; D018738:Hexamethonium / Q000494:pharmacology; D007213:Indomethacin / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D011453:Prostaglandins / Q000502:physiology; D011817:Rabbits; D011978:Receptors, Nicotinic / Q000187:drug effects* / Q000378:metabolism
D015220:Calcium Channels; D018377:Neurotransmitter Agents; D018722:Nicotinic Agonists; D011453:Prostaglandins; D011978:Receptors, Nicotinic; D002104:Cadmium; D009569:Nitric Oxide; D018738:Hexamethonium; D009538:Nicotine; D002118:Calcium; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin