OBJECTIVETo study the effect of herbal compound 861 (HB861) on expression and activity of nitric oxide synthase (NOS) in hepatic stellate cells (HSC), and to explore the feasibility of its application in preventing and treating the early portal hypertension.

METHODSHSC of HSC-T6 cell line (1 x 10(5)/ml) were cultured in dish with 95% O2 plus 5% CO2 under 37 degrees C for 24 hrs, then divided into 5 groups, 6 dishes in each group. Group A was the blank control group. To Group B-E, HB861 2 mg/ml, HB861 4 mg/ml, HB861 8 mg/ml, HB861 4 mg/ml + NW-Nitro-L-Arginine Methyl Ester (L-NAME)4 mg/ml were added separately, and continuously cultured for 24 hrs. NOS activity was measured using colorimetry, NO level was determined by nitrate reductase technique. The cells were fixed by 4% paraformaldehyde for 2 hrs for test HSC-T6 iNOS expression by immunocyto-chemical method.

RESULTSHB861 in 2 mg/ml, 4 mg/ml and 8 mg/ml could increase HSC-T6 NOS activity from 1.7 +/- 0.1 to 2.5 +/- 0.3, 3.5 +/- 0.4 and 3.7 +/- 0.9 respectively (P < 0.01), the NO levels in supernatant were increased in parallel from 56.1 +/- 4.8 to 90.7 +/- 4.6, 99.7 +/- 4.1 and 109.0 +/- 2.7 respectively (P < 0.01). L-NAME could not inhibit the effect of HB861 in increasing the synthesis and secretion of NO by activated HSC-T6. Immuno-cyto-chemical study showed that there was iNOS expression in cytoplasm, and which could be increased by HB861.

CONCLUSIONThe activated HSC-T6 showed positive iNOS expression, suggesting it could produce NO. HB861 could markedly increase HSC-T6 iNOS expression and NOS activity, enhance the NO synthesis and secretion, it also could inhibit the contractility of activated HSC by way of increase HSC to secrete NO, so as to lower the resistance in hepatic sinusoid, therefore would play important role in preventing and treating of early portal hypertension.