Effect of Cholera Toxin on Fluid Absorption and Villus Lymph Pressure in Dog Jejunal Mucosa

Abstract

Dog jejunal mucosa exposed to purified cholera toxin secreted fluid in vivo. When it was studied in vitro, net fluid transport was from mucosal to serosal side or absorption. The fluid absorption rate was, however, markedly reduced. The villus lymph pressure was also decreased in the toxin-exposed villi. These findings indicate that the net fluid absorptive activity by the villus is reduced by the action of cholera toxin. Within a wide range of dose of cholera toxin or exposure time in vivo, the fluid absorption rate in vitro was diminished to the same extent (about 50% of the control value). On the other hand, the fluid secretion rate in vivo increased with increasing dose of toxin or exposure time. These findings suggest that cholera toxin reduces the absorptive function of the villus epithelium, but the excessive production of fluid involves other functional areas such as the crypts or microcirculatory disturbance, or both. The composition of the absorbate with respect to glucose, Na, and C1 was the same in the control and toxin-exposed mucosa, suggesting that a simultaneous toxin-induced secretion with a different composition might not occur in vitro. It is concluded that both a reduction of fluid absorption and an increase of fluid secretion from intestinal mucosa may be involved in net fluid production in cholera.