Down-regulation of prostaglandin F 2α receptors in rat liver during chronic endotoxemia

Abstract

Prostaglandin (PG) F 2α binding parameters were measured in purified plasma membrane preparations isolated from livers of chronically endotoxin-(ET) treated rats and corresponding controls. Two classes of binding sites were detected in both groups: high affinity, low capacity, with a K D of 44.4 ± 8.8 nM for saline- and 28.6 ± 11.3 nM for ET-treated rats (n = 5 for both, p > 0.05) and low affinity, high capacity with a K D of 1.12 ± 0.49 μM for saline- and 1.24 ± 0.43 μM for ET-treated rats (p > 0.05). B max values for high affinity sites were 1.01 ± 0.18 fmol.mg −1 protein for saline- and 1.02 ± 0.54 (same units) for ET-treated rats (p > 0.05). There was a significant difference (p < 0.01) between the B max values for low affinity sites in saline- (675 ± 332 fmol.mg −1 protein) and ET-treated rats (12 ± 1, same units). This decrease in the amount of PGF 2α low affinity high capacity binding sites may underlie the depression of the PGF 2α stimulatory effect on hepatic gluconeogenesis induced by non-lethal, chronic ET treatment of rats, recently described by us (9).