(−)-Epigallocatechin Gallate Inhibits the Pacemaker Activity of Interstitial Cells of Cajal of Mouse Small Intestine

(−)-Epigallocatechin Gallate Inhibits the Pacemaker Activity of Interstitial Cells of Cajal of Mouse Small Intestine

The effects of (−)-epigallocatechin gallate (EGCG) on pacemaker activities of cultured interstitial cells of Cajal (ICC) from murine small intestine were investigated using whole-cell patch-clamp technique at 30^oC and Ca^2＋ image analysis. ICC generated spontaneous pacemaker currents at a holding potential of −70 mV. The treatment of ICC with EGCG resulted in a dose-dependent decrease in the frequency and amplitude of pacemaker currents. SQ-22536, an adenylate cyclase inhibitor, and ODQ, a guanylate cyclase inhibitor, did not inhibit the effects of EGCG. EGCG-induced effects on pacemaker currents were not inhibited by glibenclamide, an ATP-sensitive K^＋ channel blocker and TEA, a Ca^2＋-activated K^＋ channel blocker. Also, we found that EGCG inhibited the spontaneous [Ca^2＋]_i oscillations in cultured ICC. In conclusion, EGCG inhibited the pacemaker activity of ICC and reduced [Ca^2＋]_ioscillations by cAMP-, cGMP-, ATP-sensitive K+ channel-independent manner.