Nitric oxide inhibits calcium release from sarcoplasmic reticulum of porcine tracheal smooth muscle cells.
In the present study, effects of the nitric oxide donor, S-nitroso-N-acetylpenicillamine (SNAP), on sarcoplasmic reticulum (SR) Ca2+ release were examined in freshly dissociated porcine tracheal smooth muscle (TSM) cells. Fura 2-loaded TSM cells were imaged using video fluorescence microscopy. SR Ca2+ release was induced by acetylcholine (ACh), which acts principally through inositol 1,4,5-trisphosphate (IP3) receptors, and by caffeine, which acts principally through ryanodine receptors (RyR). SNAP inhibited ACh-induced SR Ca2+ release at both 0 and 2.5 mM extracellular Ca2+. Degraded SNAP had no effect on ACh-induced SR Ca2+ release. SNAP also inhibited caffeine-induced SR Ca2+ release. ACh-induced Ca2+ influx was not affected by SNAP when SR reloading was blocked by thapsigargin. SNAP also did not affect SR Ca2+ reuptake. The membrane-permeant analogue of guanosine 3',5'-cyclic monophosphate (cGMP), 8-bromo-cGMP, mimicked the effects of SNAP. These results suggest that, in porcine TSM cells, SNAP reduces the intracellular Ca2+ response to ACh and caffeine by inhibiting SR Ca2+ release through both IP3 and RyR, but not by inhibiting influx or repletion of the SR Ca2+ stores. These effects are likely mediated via cGMP-dependent mechanisms.
Kannan
M S
MS
Department of Veterinary Pathobiology, University of Minnesota, St. Paul 55108, USA. kanna001@maroon.tc.umn.edu
Prakash
Y S
YS
Johnson
D E
DE
Sieck
G C
GC
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism; D009130:Muscle, Smooth / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D009994:Osmolar Concentration; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D026423:S-Nitroso-N-Acetylpenicillamine; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D013552:Swine; D014132:Trachea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D002110:Caffeine; D026423:S-Nitroso-N-Acetylpenicillamine; D010396:Penicillamine; D006152:Cyclic GMP; D000109:Acetylcholine; D002118:Calcium