Lack of evidence in vivo for nitrergic inhibitionby Escherichia coli (STa) enterotoxin of fluidabsorption from rat proximal jejunum

ABSTRACT

Fluid absorption from the proximal jejunum of the anaesthetised rat was measuredin vivo by fluid recovery. As expected, heat stable (STa) enterotoxin fromE.coli reduced fluid absorption. Neither intraperitoneal L-NAME, thought to inhibita putative neurally mediated action of STa, nor similar doses of D-NAME,ameliorated the inhibitory effect on jejunal fluid absorption of STa. Luminally perfused10 mM sodium nitroprusside (SNP) had no effect on fluid absorption whenexpressed per gram dry weight per hour but reduced fluid absorption whenexpressed per cm length per hour. Similarly, 80 but not 40 mg/Kg of L-NAMEreduced fluid absorption when expressed per cm length per hour, while the samedose of D-NAME did not. L-NAME and SNP significantly increased the wet weightto dry weight and the length to dry weight ratio of perfused loops. We conjecturethat smooth muscle relaxation caused by these compounds increases interstitial fluidvolumes that can be misconstrued as changes in absorption when this is expressed percm length or per tissue wet weight. When fluid absorption is expressed per gram dryweight of tissue, there is no evidence for a role of nitric oxide in normal or STa inhibitedfluid absorption (AU)

RESUMEN

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