Patterns of adrenoceptor change during liver regeneration of the wistar kyoto rat: A bunding study

RESUMO

Background. Adrenoceptors have been involved in the regulation of hepatocyte proliferation after partial hepatectomy, as well as in primary culture. This report characterized Ó1 and ß-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 Ó1- and ß-adrenoceptors, respectively) were done in liver plasma membranes from 6-monthold rats subjected to 70 percent hepatectomy followed by hepatic regeneration. Results. [3H]Prazosin and [3H]dihydroalprenolol binding gave control Bmax values of 101 ñ 10 and 12 ñ 1 fmol/mg protein and Kd of 0.50 ñ 0.10 and 4.1 ñ 0.4 nM for Ó1- and ß-adrenoceptors, respectively. Ó1-Adrenoceptor number and Kd increades at 24 and 48 h and returned to control values at 72 and 96 h after surgery, whereas ß-adrenoceptors augmented at 48 and 72 h, with a Kd change at 24 and 48 h postherapetectomy. Conclusions.These results suggest that dual control of Ó1- and ß-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