DCEBIO stimulates Cl−secretion in the mouse jejunum

Abstract

We investigated the effects of 5,6-dichloro-1-ethyl-1,3-dihydro-2 H-benzimidazol-2-one(DCEBIO) on the Cl−secretory response of the mouse jejunum using the Ussing short-circuit current ( Isc) technique. DCEBIO stimulated a concentration-dependent, sustained increase in Isc(EC5041 ± 1 μM). Pretreating tissues with 0.25 μM forskolin reduced the concentration-dependent increase in Iscby DCEBIO and increased the EC50(53 ± 5 μM). Bumetanide blocked (82 ± 5%) the DCEBIO-stimulated Iscconsistent with Cl−secretion. DCEBIO was a more potent stimulator of Cl−secretion than its parent molecule, 1-ethyl-2-benzimidazolinone. Glibenclamide or NPPB reduced the DCEBIO-stimulated Iscby >80% indicating the participation of CFTR in the DCEBIO-stimulated Iscresponse. Clotrimazole reduced DCEBIO-stimulated Iscby 67 ± 15%, suggesting the participation of the intermediate conductance Ca2+-activated K+channel (IKCa) in the DCEBIO-activated Iscresponse. In the presence of maximum forskolin (10 μM), the DCEBIO response was reduced and biphasic, reaching a peak response of the change in Iscof 43 ± 5 μA/cm2and then falling to a steady-state response of 17 ± 10 μA/cm2compared with DCEBIO control tissues (61 ± 6 μA/cm2). The forskolin-stimulated Iscin the presence of DCEBIO was reduced compared with forskolin control tissues. Similar results were observed with DCEBIO and 8-BrcAMP where adenylate cyclase was bypassed. H89, a PKA inhibitor, reduced the DCEBIO-activated Isc, providing evidence that DCEBIO increased Cl−secretion via a cAMP/PKA-dependent manner. These data suggest that DCEBIO stimulates Cl−secretion of the mouse jejunum and that DCEBIO targets components of the Cl−secretory mechanism.