Characteristics of [3H]CGP12177 binding sites at beta 2- and beta 3-adrenoceptors in the guinea pig taenia caecum.
1. Experiments were carried out to characterize the [3H]CGP12177 binding sites in the microsomal fraction from the guinea pig taenia caecum. 2. The Scatchard plot in the absence of butoxamine (10(-4) M) or bupranolol (10(-4) M) was concave, suggesting two affinity sites: high and low affinity binding sites. 3. The Scatchard plot in the presence of butoxamine gave a straight line, indicating only the low affinity site. 4. The Scatchard plot in the presence of bupranolol was undetectable. 5. These results suggest that the high affinity binding sites for [3H]CGP12177 correspond to beta 2-adrenoceptors in the microsomal fraction from the guinea pig taenia caecum, whereas the low affinity binding sites represent beta 3-adrenoceptors.
Koike
K
K
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Takayanagi
I
I
D000318:Adrenergic beta-Agonists / Q000378:metabolism*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D002046:Bupranolol / Q000494:pharmacology; D002078:Butoxamine / Q000494:pharmacology; D002432:Cecum / Q000187:drug effects* / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000187:drug effects* / Q000378:metabolism; D009130:Muscle, Smooth / Q000187:drug effects* / Q000378:metabolism; D011412:Propanolamines / Q000378:metabolism*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D022702:Receptors, Adrenergic, beta-3
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D018343:Receptors, Adrenergic, beta-2; D022702:Receptors, Adrenergic, beta-3; D002078:Butoxamine; D002046:Bupranolol; C033394:CGP 12177