Effects of guanosine 5'-triphosphate on the specificity of irreversible alpha 1-antagonisms by phenoxybenzamine in rabbit thoracic aorta.
Phenylephrine displacement curves for the specific binding of [3H]prazosin in the membrane fraction prepared from rabbit thoracic aorta showed high- and low-affinity sites with slope factors significantly less than unity. The irreversible alpha 1B-antagonist phenoxybenzamine shifted the binding sites to single high affinity sites with a slope factor close to unity in the presence of the metabolically stable GTP analog GTP gamma-S. These results indicate that phenoxybenzamine may have affected selectively the low affinity site to phenylephrine in the presence of GTP gamma-S.
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
N
N
Kokubu
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M
Satoh
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Takayanagi
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D001667:Binding, Competitive / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010643:Phenoxybenzamine / Q000494:pharmacology*; D010656:Phenylephrine / Q000378:metabolism; D011817:Rabbits; D013873:Thionucleotides / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D013873:Thionucleotides; D010643:Phenoxybenzamine; D006153:Guanosine Diphosphate; D010656:Phenylephrine; C022571:adenosine 5'-O-(3-thiotriphosphate); D016244:Guanosine 5'-O-(3-Thiotriphosphate); C023427:guanosine 5'-O-(2-thiodiphosphate); D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D019204:GTP-Binding Proteins