Evaluation of an electrochemical microprobe for direct NO measurement in the rat gastric fundus.
Nitric oxide (NO) is an inhibitory nonadrenergic, noncholinergic (NANC) neurotransmitter in the rat gastric fundus and is released upon electrical or pharmacological stimulation of the inhibitory NANC neurons. In this study, it was attempted to measure the release of NO from the rat gastric fundus upon electrical stimulation or administration of nicotine directly via an electrochemical probe (ISO-NO). The system was evaluated by adding exogenous NO. Addition of exogenous NO induced concentration-dependent relaxation of the rat gastric fundus and an increase in the ISO-NO probe baseline current. The concentration of NO detected by the ISO-NO probe was lower than the concentration of NO administered. When no tissue was present, higher concentrations of NO were detected than in the presence of a tissue. In the absence of 95% O2/5% CO2 the concentration of NO detected was highest. Electrical stimulation induced relaxations of the rat gastric fundus which were reduced by NG-nitro-L-arginine methylester (L-NAME). An increase in the ISO-NO probe baseline current was also observed, but this was duc to nonspecific effects as the response also occurred without a tissue present and was not sensitive to L-NAME. Nicotine induced relaxations, which were reduced by L-NAME, but the ISO-NO probe baseline current remained unaltered, even in the presence of L-arginine plus superoxide dismutase. It can be concluded that it is not possible to detect directly the NO release from the rat gastric fundus upon electrical or pharmacological stimulation of the NANC neurons with the ISO-NO probe.
Smits
G J
GJ
Heymans Institute of Pharmacology, University of Gen, Belgium.
Lefebvre
R A
RA
D000818:Animals; D004558:Electric Stimulation; D004563:Electrochemistry / Q000295:instrumentation / Q000379:methods; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005748:Gastric Fundus / Q000737:chemistry* / Q000187:drug effects; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009538:Nicotine / Q000494:pharmacology; D009569:Nitric Oxide / Q000032:analysis*; D051381:Rats; D017208:Rats, Wistar
D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D009538:Nicotine; D019331:NG-Nitroarginine Methyl Ester