[Modulation of the intensity of the non-quantal transmitter release by nitric oxide (NO) at the neuromuscular junction].
In the rat diaphragm muscle, nitric oxide (NO)--sodium nitroprusside (SNP) and S-nitroso-N-acetylpenicillamine (SNAP), as well as substrate for the NO synthesis L-arginine, decrease the level of hyperpolarization of the muscle fibre membrane after acetylcholine receptor blockade by the d-TC and irreversible acetylcholinesterase inhibition by armin (H-effect). Contrary to that, disruption of the NO synthesis in the muscle fibres by the NO-synthase inhibitor NG-nitrol-L-arginine methyl ester (L-NAME) results in enhancement of the H-effect both in vitro and in vivo. Inactivated SNP and inactive forms of arginine and NAME did not affect the H-effect magnitude. Haemoglobin, effectively binding the NO molecules, abolishes the suppressing effects of the SNP, SNAP and L-arginine upon the H-effect. The findings suggest that the NO could be acting as a modulator of nonquantal transmitter release at the mammalian neuromuscular junction.
Mukhtarov
M R
MR
Kazan Institute of Biochemistry, Russia.
Urazaev
A Kh
AKh
Nikol'skiĭ
E E
EE
Vyskocil
F
F
D000109:Acetylcholine / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001138:Armin / Q000494:pharmacology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D003964:Diaphragm / Q000294:innervation / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000378:metabolism; D066298:In Vitro Techniques; D008564:Membrane Potentials; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D002800:Cholinesterase Inhibitors; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; C110881:S-nitro-N-acetylpenicillamine; D009599:Nitroprusside; D009569:Nitric Oxide; D001120:Arginine; D010396:Penicillamine; D001138:Armin; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester