Na+/Ca2+ exchanger contributes to stool transport inmice with experimental diarrhea

[摘要] The Na+/Ca2+ exchanger (NCX) is a bidirectional transporter that iscontrolled by membrane potential and transmembrane gradients of Na+ andCa2+. To reveal the functional role of NCX on gastrointestinal motility, wehave previously used NCX1 and NCX2 heterozygote knockout mice (HET). We found that NCX1and NCX2 play important roles in the motility of the gastric fundus, ileum and distalcolon. Therefore, we believed that NCX1 and NCX2 play an important role in transport ofintestinal contents. Here, we investigated the role of NCX in a mouse model ofdrug-induced diarrhea. The fecal consistencies in NCX1 HET and NCX2 HET were assessedusing a diarrhea induced by magnesium sulfate, 5-hydroxytryptamine (5-HT) andprostaglandin E2 (PGE2). NCX2 HET, but not NCX1 HET, exacerbatedmagnesium sulfate-induced diarrhea by increasing watery fecals. Likewise, 5-HT-induceddiarrheas were exacerbated in NCX2 HET, but not NCX1 HET. However, NCX1 HET and NCX2 HETdemonstrated PGE2 induced diarrhea similar to those of wild-type mice (WT). Aswell as the result of the distal colon shown previously, in the proximal and transversecolons of WT, the myenteric plexus layers and the longitudinal and circular muscle layerswere strongly immunoreactive to NCX1 and NCX2. In this study, we demonstrate that NCX2 hasimportant roles in development of diarrhea.

[学科分类] 兽医学

[关键词] diarrhea;5-hydroxytryptamine;magnesium sulphate;myenteric neurons;na+/Ca2+exchanger