Prolonged incubation with neuropeptide Y upregulates β-adrenoceptors yet does not cause supersensitivity of β-adrenoceptor signaling

Abstract

In neonatal rat ventricular myocytes prolonged incubation with 1 μM neuropeptide Y (2 h–48 h) increased β-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 adenylylcyclase activity stimulated by 5′-guanylylimidodiphosphate or (−)-isoprenaline, probably because of a neuropeptide Y-induced decrease in affinity of the β-adrenoceptor for agonist. Thus, chronic incubation with an inhibitory agonist does not inevitably lead to supersensitivity of the adenylylcyclase pathway.