Characterization of the alpha 1B-adrenergic receptors of chicken hepatocytes. Signal transduction and actions.
1. In chicken hepatocytes, alpha 1-adrenoceptor activation increased: (a) phosphatidylinositol labeling; (b) production of inositol trisphosphate; (c) cytosol calcium; and (d) phosphorylase activity. 2. Prazosin (Ki approximately 0.2-0.4 nM) was more potent in inhibiting these actions than 5-methyl-urapidil (Ki approximately 30-60 nM); these actions were sensitive to chlorethylclonidine suggesting the involvement of alpha 1B-adrenoceptors. 3. The stimulation of phosphoinositide turnover was insensitive to pertussis toxin. 4. In chicken liver membranes, [3H]prazosin binding sites (Bmax 872 fmol/mg protein) with high affinity for prazosin (KD 0.3 nM; Ki 0.4 nM) and lower affinity for 5-methyl-urapidil (Ki 46 nM) were detected, consistent with the presence of alpha 1B-adrenoceptors.
Gutiérrez-Venegas
G
G
Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F.
García-Sáinz
J A
JA
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002645:Chickens; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D037342:Pertussis Toxin; D010656:Phenylephrine / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D011224:Prazosin / Q000378:metabolism; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D013816:Thermodynamics; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000317:Adrenergic alpha-Antagonists; D010716:Phosphatidylinositols; D010879:Piperazines; D018340:Receptors, Adrenergic, alpha-1; D010566:Virulence Factors, Bordetella; C057446:5-methylurapidil; D010656:Phenylephrine; D037342:Pertussis Toxin; D002118:Calcium; D009638:Norepinephrine; D011224:Prazosin; D004837:Epinephrine