Nicotine potentiates the neurogenic contractile response of rabbit bladder tissue via nicotinic acetylcholine receptors: nitric oxide and prostaglandins have no role in this process.
Nicotine, a nicotinic acetylcholine receptors (nAChRs) agonist, has a role in modulation of the neurotransmitter release following nerve stimulation in both the central and peripheral nervous systems. The aim of this study was to determine whether electrical field stimulation (EFS)-evoked contractions are altered in rabbit bladder in the presence of nicotine and, if an alteration occurs, to investigate the effects of nitric oxide and prostaglandins on nicotine-induced alternation in isolated rabbit bladder. EFS-evoked contractile responses from rabbit bladder obtained were recorded with isometric force displacement transducers. Nicotine was added to preparations at various concentrations. The effects of hexamethonium, cadmium (Cd(2+)), indomethacin and N-nitro-L-arginine methyl ester (L-NAME) were tested on the EFS-evoked contractions in the presence of nicotine. Nicotine led to a dose-dependent increase in the amplitude of the EFS-evoked contractile responses. Cd(2+) and hexamethonium inhibited the nicotine-induced increase in EFS-evoked responses, whereas indomethacin and L-NAME had no effect. In conclusion, nicotine increased the EFS-evoked contractile responses possibly by facilitating release of neurotransmitters from nerve terminals by a mechanism dependent on the influx of Ca(2+) from voltage-gated Ca(2+) channels (VGCCs) via activation of nAChRs in isolated rabbit bladder. Nitric oxide and prostaglandins do not have a physiological role in the regulation of neurotransmitter release.
Vural
Ismail Mert
IM
Department of Pharmacology, Medical School, Gazi University, 06510 Besevler Ankara, Turkey. imvural@yahoo.com
Ozturk
Gokce Sevim
GS
Ercan
Zeynep Sevim
ZS
Sarioglu
Yusuf
Y
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects*; D009119:Muscle Contraction / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology; D011453:Prostaglandins / Q000502:physiology; D011817:Rabbits; D011978:Receptors, Nicotinic / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000294:innervation / Q000378:metabolism
D018722:Nicotinic Agonists; D011453:Prostaglandins; D011978:Receptors, Nicotinic; D009569:Nitric Oxide; D009538:Nicotine