L - Arginine - induced muscle cells current in portal

In our previous report, we showed that L-arginine induced depolarization of smoolh muscle cells of the rat portal vein with an increasecl contraction. To clarify the ionic mechanism of the membrane depolarization, the effect of I.-arginine on the holding current was studied in freshly isolated smooth muscle cells of the rat portal vein. The whole-cell patch-clamp teehnique was used, with the membrane potential held at -60 mV. In the presence of Na" in thc perfusate, L-arginine 10 mM induccd an inward current in about 50% of the cells. In Na'-deficient perfusate, I,-arginine 10 mM increased the amplitude of the inward current in a Na' concentration-dependent manner, BCH, an inhibitor of the Na'-dependent amino acid transporter, ceased the Trarginine-induced current, These results indicate that L-arginine induces an inward current via Na'dcpendent mechanisms in rat portal venous smeoth muscle cells.