[The mediation effects of endothelin-1 on human mesangial cell proliferation stimulated by thrombin]

To investigate the effects of endothelin-1 (ET-1) on mesangial cell proliferation stimulated by thrombin.

With cultured human mesangial cells (HMC), the following tests were performed. (1) Stimulative tests: After thrombin stimulation, HMC proliferation was determined by MTT method, concentration of ET-1 in supernatant was measured with radioimmunoassay (RIA) and preproendothelin-1 (ppET-1) mRNA expression of HMC was analysed by Northern blot hybridization. (2) Inhibitory test: The influence of ET-1 inhibitors on the HMC proliferation following thrombin stimulation at three different levels, i.e. ET-1 antiserum, selective ET receptor-type A (ET(A)) antagonist and antisense oligodeoxynucleotide for ppET-1, was measured by MTT test respectively.

(1) HMC proliferation was stimulated by thrombin in dose dependent manner and in relation to the time of stimulation. The peak growth level was attained in thrombin concentration of 16 U/ml and incubation time of 16 hours. ET-1 secretion by HMC was increased in parallel with the dose curve and time curve of HMC proliferation; HMC ppET-1 mRNA expression was up-regulated by thrombin 16 U/ml with incubation time of 8 hours and 16 hours respectively (7.9 fold, 3.4 fold versus control group). (2) ET-1 inhibitors, ET-1 antiserum, selective ET(A) receptor antagonist and antisense oligodeoxynucleotide for ppET-1 all significantly inhibit HMC proliferation stimulated by thrombin.

Thrombin stimulates HMC to produce ET-1 and ET-1 mediates the HMC proliferation.