ABSTRACT
<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>
Subject(s)
Animals , Female , Male , Rats , Arginine , Pharmacology , Cells, Cultured , Mesenteric Artery, Superior , Nitric Oxide , Physiology , Phosphorylation , Potassium Channels, Calcium-Activated , Metabolism , Protein Subunits , Rats, Wistar , Shock, Hemorrhagic , Metabolism , Tetraethylammonium Compounds , Pharmacology , Tyrosine , Metabolism , VasoconstrictionABSTRACT
Objective To investigate the role of β-endorphin (β-EP) in conA-induced spleen cell proliferation after traumatic hemorrhagic shock. Methods ①Wistar rats with traumatic hemorrhagic shock were used and killed 0, 1, 3, 6,12 and 24 h after traumatic hemorrhagic shock. Plasma specimens were collected and β-EP levels in plasma were detected. Rats with sham-operation served as the control. ②Spleen cells isolated from normal rats were cultured in shock plasma (group Ⅰ), inactivated shock plasma (group Ⅱ) and shock plasma+β-EP antiserum (group Ⅲ) respectively. Con A-induced spleen cell proliferation was observed. Results ①The plasma β-EP level was elevated significantly immediately after shock, and reached the peak 1 h later, then showed a deceasing tendency and restored to the level as before shock at 24 h. ②Shock plasma remarkedly suppressed spleen cell response to the mitogen conA (P<0.01) compared with control; ConA-induced spleen cell proliferative function in group Ⅱ was significantly increased than that in group Ⅰ (P<0.01), so did in group Ⅲ, which still lower than in control. Conclusion The significantly elevated β-EP in the plasma after hemorrhagic shock might play an important role in inhibiting the proliferation of spleen cells.
ABSTRACT
Objective To investigate the role of β-endorphin (β-EP) in conA-induced spleen cell proliferation after traumatic hemorrhagic shock. Methods ①Wistar rats with traumatic hemorrhagic shock were used and killed 0, 1, 3, 6,12 and 24 h after traumatic hemorrhagic shock. Plasma specimens were collected and β-EP levels in plasma were detected. Rats with sham-operation served as the control. ②Spleen cells isolated from normal rats were cultured in shock plasma (group Ⅰ), inactivated shock plasma (group Ⅱ) and shock plasma+β-EP antiserum (group Ⅲ) respectively. Con A-induced spleen cell proliferation was observed. Results ①The plasma β-EP level was elevated significantly immediately after shock, and reached the peak 1 h later, then showed a deceasing tendency and restored to the level as before shock at 24 h. ②Shock plasma remarkedly suppressed spleen cell response to the mitogen conA (P<0.01) compared with control; ConA-induced spleen cell proliferative function in group Ⅱ was significantly increased than that in group Ⅰ (P<0.01), so did in group Ⅲ, which still lower than in control. Conclusion The significantly elevated β-EP in the plasma after hemorrhagic shock might play an important role in inhibiting the proliferation of spleen cells.