Effects of alpha(1)-acid glycoprotein on isometric tension of mouse aorta.
We examined the effects of human alpha(1)-acid glycoprotein on isometric tension of mouse aortic rings. alpha(1)-Acid glycoprotein (7.5-75 microM) produced a transient, concentration-dependent relaxation of the phenylephrine-precontracted preparation. Although N(G)-nitro-L-arginine methyl ester or removal of endothelium rarely affected the alpha(1)-acid glycoprotein-induced relaxation, extracellular heparin inhibited the alpha(1)-acid glycoprotein-induced relaxation. In 10 mM Ca(2+)-containing external solutions, the alpha(1)-acid glycoprotein-induced relaxation was significantly potentiated. In the 60 mM KCl-precontracted preparation, alpha(1)-acid glycoprotein produced weaker relaxation than in the phenylephrine-precontracted preparation. These results suggest that the vasorelaxant effect of alpha(1)-acid glycoprotein is mainly achieved by block of Ca(2+) entry in the vascular smooth muscle cells. The interaction between alpha(1)-acid glycoprotein molecules and plasmalemmal Ca(2+) entry channels may be modified by extracellular Ca(2+) and heparin.
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009961:Orosomucoid / Q000494:pharmacology* / Q000502:physiology; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D009961:Orosomucoid; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D011189:Potassium Chloride; D006493:Heparin