Receptor tyrosine and MAP kinase are involved in effects of H2O2 on interstitial cells of Cajal in murine intestine

Hydrogen peroxide (H2O2) is involved in intestinal motility through changes of smooth muscle activity. However, there is no report as to the modulatory effects of H2O2 on interstitial cells of Cajal (ICC). We investigated the H2O2 effects and signal transductions to determine whether the intestinal motility can be modulated through ICC. We performed whole-cell patch clamp in cultured ICC from murine intestine and molecular analyses. H2O2 hyperpolarized the membrane and inhibited pacemaker currents. These effects were inhibited by glibenclamide, an inhibitor of ATP-sensitive K+ (K-ATP) channels. The free-radical scavenger catalase inhibited the H2O2-induced effects. MAFP and AACOCF(3) (a cytosolic phospholipase A(2) inhibitors) or SC-560 and NS-398 (a selective COX-1 and 2 inhibitor) or AH6809 (an EP2 receptor antagonist) inhibited the H2O2-induced effects. PD98059 (a mitogen activated/ERK-activating protein kinase inhibitor) inhibited the H2O2-induced effects, though SB-203580 (a p38 MAPK inhibitor) or a JNK inhibitor did not affect. H2O2-induced effects could not be inhibited by LY-294002 (an inhibitor of PI3-kinases), calphostin C (a protein kinase C inhibitor) or SQ-22536 (an adenylate cyclase inhibitor). Adenoviral infection analysis revealed H2O2 stimulated tyrosine kinase activity and AG 1478 (an antagonist of epidermal growth factor receptor tyrosine kinase) inhibited the H2O2-induced effects. These results suggest H2O2 can modulate ICC pacemaker activity and this occur by the activation of K-ATP channels through PGE(2) production via receptor tyrosine kinase-dependent MAP kinase activation.