Effects of octreotide on expression of L-type voltage-operated calcium channels and on intracellular Ca~(2+) in activated hepatic stellate cells

摘要

Background The contractility of hepatic stellate cells (HSCs) may play an important role in the pathogenesis of cirrhosis with portal hypertension. The aim of this study was to research the effects of octreotide, an analogue of somatostatin, on intracellular Ca~(2+) and on the expression of L-type voltage-operated calcium channels (L-VOCCs) in activated HSCs, and to try to survey the use of octreotide in treatment and prevention of cirrhosis with portal hypertension complications. Methods HSC-T_6, an activated HSCs line, was plated on small glass coverslips in 35-mm culture dishes at a density of 1 x 10~5/ml, and incubated in DMEM media for 24 hours. After the cells were loaded with Fluo-3/AM, intracellular Ca~(2+) was measured by Laser Scanning Confocal Microscopy (LSCM). The dynamic changes in activated HSCs of intracellular Ca~(2+), stimulated by octreotide, endothelin-1, and KCl, respectively, were also determined by LSCM. Each experiment was repeated six times. L-VOCC expression in HSCs was estimated by immunocytochemistry. Results After octreotide stimulation, a signifcant decrease in the intracellular Ca~(2+) of activated HSCs was observed. However, octreotide did not inhibit the increases in intracellular Ca~(2+) after stimulation by KCI and endothelin-1. Moreover, octreotide did not significantly affect L-VOCC expression. These results suggest that neither L-VOCC nor endothelin-1 receptors in activated HSCs are inhibited by octreotide. Conclusions Octreotide may decrease portal hypertension and intrahepatic vascular tension by inhibiting activated HSCs contractility through decreases in intracellular Ca~(2+). The somatostatin receptors in activated HSCs may be inhibited by octreotide.