Nitric oxide donors inhibit calcium stimulated contraction in detrusor muscle of goat

Abstract

The present study was undertaken to examine the role of nitric oxide on the modulation of Ca²⺠in the urinary bladder muscles of goat. CaClâ‚‚ (10â»âµ M – 10â»Â² M) induced cumulative concentration-contraction curves were generated at an increment of 0.5 log unit in isolated detrusor muscle strips in organ bath studies. SNP (sodium nitroprusside) and SIN–1(3-morpholino-sydnonimines) at a concentration of 10â»â¶ M and 10â»âµ M were used to study the role of NO on extra cellular Ca²âº. Results were compared with a known L-type Ca²⺠channel blocker, nifedipine (10â»â¶M). In another set of experiments, to study the role of NO on intra-cellular Ca²âº, carbachol (CCh, 10â»â´ M) induced sub-maximal contractions of detrusor tissues were produced in Ca²âº-free EGTA containing PSS either in the absence or presence of SNP and SIN-1. The present investigation showed that NO donors SIN-1 and SNP concentration dependently shifted the concentration-contraction curves of CaClâ‚‚. The NO donors also inhibited the CCh-induced contraction. Thus, it can be concluded that SNP and SIN-1 are inhibitors of both extracellular as well as intracellular Ca²⺠in goat detrusor muscle.