Effect of nitric oxide-induced tyrosine phosphorylation of calcium-activated potassium channel alpha subunit on vascular hyporesponsiveness in rats.
OBJECTIVE
To study the effect of nitric oxide-induced tyrosine phosphorylation of large-conductance calcium-activated potassium (BK(Ca)) channel alpha subunit on vascular hyporesponsiveness in rats.


METHODS
A total of 46 Wistar rats of either sex, weighing 250 g +/- 20 g, were used in this study. Models of vascular hyporesponsiveness induced by hemorrhagic shock (30 mm Hg for 2 hours) in vivo and by L-arginine in vitro were established respectively. The vascular responsiveness of isolated superior mesenteric arteries to norepinephrine was observed. Tyrosine phosphorylation of BK(Ca) alpha subunit was evaluated with methods of immunoprecipitation and Western blotting.


RESULTS
In the smooth muscle cells of the superior mesenteric arteries, the expression of BK(Ca) alpha subunit tyrosine phosphorylation increased following hemorrhagic shock, and L-arginine could induce BK(Ca )channel alpha subunit tyrosine phosphorylation in a time- and dose-dependent manner. L-NAME (Nomega-nitro-L-arginine-methyl-ester), a nitric oxide synthetase inhibitor, could partly restore the decreased vasoresponsiveness of the superior mesenteric arteries after hemorrhagic shock in rats. Down-regulating the protein tyrosine phosphorylation with genistein, a widely-used special protein tyrosine kinase inhibitor, could partly improve the decreased vasoresponsiveness of the superior mesenteric arteries induced by L-arginine in vitro, while up-regulating the protein tyrosine phosphorylation with Na(3)VO(4), a protein tyrosine phosphatase inhibitor, could further decrease the nitric oxide-induced vascular hyporesponsiveness, which could be partly ameliorated by 0.1 mmol/L tetrabutylammonium chloride (TEA), a selective BK(Ca )inhibitor at this concentration.


CONCLUSIONS
Nitric oxide can induce the tyrosine phosphorylation of BK(Ca) alpha subunit, which influences the vascular hyporesponsiveness in hemorrhagic shock rats or induced by L-arginine in vitro.
Zhou
Rong
R
State Key Laboratory of Trauma, Burns and Combined Injury, Department 2, Research Institute of Surgery & Daping Hospital, Third Military Medical University, Chongqing, China.
Liu
Liang-ming
LM
Hu
De-yao
DY
D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D008297:Male; D017538:Mesenteric Artery, Superior / Q000187:drug effects / Q000503:physiopathology; D009569:Nitric Oxide / Q000502:physiology*; D010766:Phosphorylation; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*; D021122:Protein Subunits; D051381:Rats; D017208:Rats, Wistar; D012771:Shock, Hemorrhagic / Q000378:metabolism*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014443:Tyrosine / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects*
D024681:Potassium Channels, Calcium-Activated; D021122:Protein Subunits; D013757:Tetraethylammonium Compounds; D009569:Nitric Oxide; D014443:Tyrosine; D001120:Arginine