Patterns of adrenoceptor change during liver regeneration of the Wistar Kyoto rat: a binding study.

BACKGROUND: Adrenoceptors have been involved in the regulation of hepatocyte proliferation after partial hepatectomy, as well as in primary culture. This report characterizes alpha 1- and beta-adrenoceptor change during the time-course of liver regeneration in adult Wistar Kyoto rats. METHODS: Saturation binding assays with 3H]prazosin or 3H]dihydroalprenolol (for alpha 1- and beta-adrenoceptors, respectively) were done in liver plasma membranes from 6-month-old rats subjected to 70% hepatectomy followed by hepatic regeneration. RESULTS: 3H]Prazosin and 3H]dihydroalprenolol binding gave control Bmax values of 101 +/- 10 and 12 +/- 1 fmol/mg protein and Kd of 0.50 +/- 0.10 and 4.1 +/- 0.4 nM for alpha 1- and beta-adrenoceptors, respectively. alpha 1-Adrenoceptor number and Kd increased at 24 and 48 h and returned to control values at 72 and 96 h after surgery, whereas beta-adrenoceptors augmented at 48 and 72 h, with a Kd change at 24 and 48 h posthepatectomy. CONCLUSIONS: These results suggest that dual control of alpha 1- and beta-adrenoceptor membrane expression could be involved in different steps during hepatocyte proliferation, and that Wistar Kyoto rats have a different adrenoceptor pattern expression from other rat strains.