Involvement of nitric oxide in the potentiation of neurogenic contraction by manganese and nickel ions in mouse urinary bladder.
Repetitive electrical field stimulation evoked muscle contractions of the isolated mouse detrusor strips, which could be abolished by tetrodotoxin (TTX). Both Mn2+ and Ni2+ (0.01-0.06 mM) enhanced neurogenic detrusor contractions in high Ca2+ (5 mM) medium. The non-cholinergic component of the evoked detrusor contractions (in the presence of atropine) was specifically sensitive to this enhancing effect by either Mn2+ or Ni2+. In contrast, the cholinergic component in alpha,beta-methylene ATP-treated detrusors remained unaffected. As compared with Mn2+ and Ni2+, other metal ions, Cu2+, Co2+, Cd2+ and UO2(2+), failed to enhancing the non-cholinergic component of neurogenic detrusor contractions. Nitric oxide synthase (NOS) inhibitors, NG-nitro-L-arginine methyl ester and 7-nitroindazole (a selective neuronal NOS inhibitor) markedly inhibited the enhancing effect by either Mn2+ or Ni2+ on the neurogenic detrusor contractions. Moreover, Mn2+ and Ni2+ did not affect the contractions induced by either carbachol or alpha,beta-methylene ATP. It is concluded from these findings that the neuronal NOS-NO generation pathway is apparently involved in the enhancing effect of Mn2+ and Ni2+ on the muscle contractions elicited by excitatory non-cholinergic neurotransmission in the mouse detrusor strips.
Liu
S H
SH
Institute of Toxicology, College of Medicine, National Taiwan University, Taipei.
Lin-Shiau
S Y
SY
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D046508:Culture Techniques / Q000379:methods; D004357:Drug Synergism; D008297:Male; D008345:Manganese / Q000494:pharmacology*; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D018377:Neurotransmitter Agents / Q000502:physiology; D009532:Nickel / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects
D002121:Calcium Channel Blockers; D018377:Neurotransmitter Agents; D009569:Nitric Oxide; D008345:Manganese; D009532:Nickel