Receptor-mediated effect of thrombin on plasminogen activator inhibitor-1 synthesis in rat osteoblast-like cells

Abstract

The effect of thrombin on components of the plasminogen activator (PA)/plasmin pathway in osteoblast-like cells has been investigated. Thrombin was found to increase PA inhibitor-1 (PAI-1) mRNA and protein in a time- and dose-dependent manner. Tissue-type plasminogen activator (t-PA) activity was inhibited in a time- and dose-dependent manner but there was no alteration of t-PA steady-state mRNA levels. Therefore it is likely that the inhibition of t-PA activity was due entirely to the inhibition of tPA by PAI-1. Thrombin induced a small but consistent transient increase in both urokinase-type plasminogen activator (u-PA) and u-PA receptor mRNA levels but no u-PA activity was detectable by t..