3-nitrotyrosine and iberiotoxin
3-nitrotyrosine has been researched along with iberiotoxin* in 1 studies
Other Studies
1 other study(ies) available for 3-nitrotyrosine and iberiotoxin
Article | Year |
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Peroxynitrite inhibits Ca2+-activated K+ channel activity in smooth muscle of human coronary arterioles.
We examined the hypothesis that ONOO-, a product of the interaction between superoxide (O2*-) and nitric oxide (NO), inhibits calcium-activated K+ (KCa) channel activity in vascular smooth muscle cells (VSMCs) of human coronary arterioles (HCAs), thereby reducing hyperpolarization-mediated vasodilation. HCAs were dissected from right atrial appendages. The interaction of ONOO- with microvessels was determined by immunohistochemistry using a nitrotyrosine antibody. Strong staining was observed in arteries exposed to authentic ONOO- or to sodium nitroprusside (SNP)+xanthine (XA)+xanthine oxidase (XO). Dilation to 10(-8) mol/L bradykinin (BK) was abolished in vessels exposed to ONOO- (-2.5+/-8%; P<0.05) but not DC-ONOO- (65+/-8%). Reduced dilation to BK was also observed after application of XO and SNP. Dilation to NS1619 (KCa channel opener) was reduced in endothelial denuded arterioles treated with ONOO-. In isolated VSMCs, whole-cell peak K+ current density was reduced by ONOO- (control 65+/-15 pA/pF; ONOO- 42+/-9 pA/pF; P<0.05). Iberiotoxin had no further effect on whole-cell K+ current. In inside-out patches, ONOO- but not DC-ONOO- decreased open state probability (NP(o)) of KCa channel by 50+/-12%. O2*- generated by XA+XO had no effect on BK-induced dilation and NP(o) of KCa channels. These results suggest that ONOO-, but not O2*-, inhibits KCa channel activity in VSMCs possibly by a direct effect. This mechanism may contribute to impaired EDHF-mediated dilation in conditions such as ischemia/reperfusion where increased activity of NO synthase occurs in the presence of excess of O2*-. Topics: Animals; Arterioles; Coronary Vessels; Female; Humans; Immunohistochemistry; In Vitro Techniques; Male; Membrane Potentials; Microscopy, Video; Middle Aged; Muscle, Smooth, Vascular; Patch-Clamp Techniques; Peptides; Peroxynitrous Acid; Potassium; Potassium Channel Blockers; Potassium Channels, Calcium-Activated; Rats; Rats, Sprague-Dawley; Tyrosine; Vasodilation; Vasodilator Agents | 2002 |