Altered jejunal potassium (Rb+) transport in piglet rotavirus enteritis

Abstract

To determine the mechanisms of K+ loss in viral diarrhea, K+ fluxes (estimated by tracer Rb+ flows) across piglet jejunum in Ussing chambers were determined. Normal jejunum was characterized by an indomethacin-sensitive short-circuit current and a small K+ secretory flow. Rotavirus-infected gut secreted K+ at high rates, probably resulting from increased prostaglandin generation because secretion was abolished by indomethacin. Tissues pretreated with indomethacin responded to 8-bromoadenosine 3',5'-cyclic monophosphate acid and 16,16-dimethyl-prostaglandin E2 with K+ secretion. The secretory response in rotavirus-infected jejunum was no greater than that in normal tissue. Serosal addition of Ca2+ ionophore A23187 caused K+ secretion in normal but not rotavirus-infected jejunum. To inhibit the basolateral uptake of K+ and reduce the driving force for secretion, ouabain was added to the bath. Ouabain unmasked a K+ absorptive process in normal intestine, which was not seen in rotavirus-infected tissue. K+ absorption was inhibited by 3-(cyanomethyl)-2-methyl-8-(phenyl-methoxy)imidazo (1,2 alpha)pyridine (Sch-28080) and omeprazole. We speculate that the high fecal K+ losses observed in human rotavirus enteritis might be caused by an imbalance between K+ secretion and an impaired apical K+ absorptive mechanism in the crypt-type epithelium.

Inhibition of Cyclooxygenase Activity Reduces Rotavirus Infection at a Postbinding Step

“…This indicates that COX inhibitors might have a broad effect on rotavirus infection, blocking rotaviruses of different serotypes and with different species specificity. In addition, our findings are in agreement with the observations that the duration of rotavirus diarrheal illness in young children is reduced after oral administration of aspirin, a nonspecific COX inhibitor similar to indomethacin (19,56,66), and that indomethacin abolished rotavirus-induced secretion of potassium ions in infected piglet jejunum (65).…”

In Vitro Potassium Transport in the Mouse Small Intestine.

“…Radioactive Rb ϩ was previously found to be useful in many studies on membrane K ϩ transport [6,7,12,13]. In the present study, the transepithelial unidirectional Rb ϩ flux values were determined by atomic absorption spectroscopy, and it was found that Rb ϩ flux faithfully reproduced 42 K ϩ flux (compare Fig.…”

“…These findings suggest that K ϩ was absorbed not only by passive diffusion through the paracellular pathway, but also by a mechanism probably operating through the cellular pathway. Although it has generally been accepted that K ϩ absorption in the small intestine occurs predominantly by passive diffusion [3][4][5], one previous in vitro study on the piglet jejunum has demonstrated the occurrence of active K ϩ absorption in the small intestine [6]. In addition, it has been reported that K ϩ influx into the rabbit ileum can be assigned to both a diffusion component and a component not affected by V t [10].…”

“…testine [12,13], and suggested to contribute to K ϩ absorption [6]. In many cases, the source of H ϩ used by a H ϩ /K ϩ exchanger is derived from CO 2 hydration [9].…”

Oral Transforming Growth Factor-α Enhances Jejunal Mucosal Recovery and Electrical Resistance in Piglet Rotavirus Enteritis

“…We recently found that exposure of piglet jejunum to the cyclooxygenase inhibitor indomethacin reduces piglet jejunal I,, (a measure of C1-secretion) and that prostaglandin E2 reduces epithelial conductance (40). We therefore attempted in the present study to minimize any effect of prostaglandins on Is, or tissue resistance by bathing tissues in a physiologic saline solution with indomethacin.…”