Prolonged incubation with neuropeptide Y upregulates beta-adrenoceptors yet does not cause supersensitivity of beta-adrenoceptor signaling.
In neonatal rat ventricular myocytes prolonged incubation with 1 microM neuropeptide Y (2 h-48 h) increased beta-adrenoceptor density 16-24% (n = 4--8, all p < 0.05), an effect prevented by pertussis toxin pretreatment. Prolonged incubation with neuropeptide Y had no effect on adenylycylclase activity stimulated by 5'-guanylylimidodiphosphate or (-)-isoprenaline, probably because of a neuropeptide Y-induced decrease in affinity of the beta-adrenoceptor for agonist. Thus, chronic incubation with an inhibitory agonist does not inevitably lead to supersensitivity of the adenylylcyclase pathway.
Rocha-Singh
K J
KJ
Cardiology Section (111C), Department of Veterans Affairs Medical Center, San Francisco, CA 94121, USA.
Matsuo
R
R
Karliner
J S
JS
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002478:Cells, Cultured; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D006352:Heart Ventricles / Q000187:drug effects / Q000201:enzymology; D007545:Isoproterenol / Q000494:pharmacology; D009478:Neuropeptide Y / Q000494:pharmacology*; D011869:Radioligand Assay; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D015398:Signal Transduction; D015854:Up-Regulation
D009478:Neuropeptide Y; D011943:Receptors, Adrenergic, beta; D006165:Guanylyl Imidodiphosphate; D000262:Adenylyl Cyclases; D007545:Isoproterenol