Effect of antagonists of adrenergic and cholinergic receptors on ion transport in the isolated rabbit caecum wall.

Abstract

A hypothesis was tested in this study that antagonists of adrenergic and cholinergic receptors affect sodium and chloride ion transport in the rabbit caecum. A modified Ussing chamber was used in the experiment. It was demonstrated that isolated caecum responded to a mechanical stimulus, which consisted in gentle rinsing of the mucous surface, with changes in transepithelial electrical potential difference. An application of ion transport inhibitors, amiloride for sodium and bumetanide for chloride ions, demonstrated that both sodium and chloride ion transport in part determined the response. Pharmaceuticals that are antagonistic at neural receptors (alpha- and beta-adrenergic, nicotinic, and muscarinic), applied both for incubation and stimulation, reduced electrical potential and inhibited responses to mechanical stimuli. Basing on the results of this experiment and literature data, one can presume that analogical responses occur in vivo, and the physiological role of the autonomic system includes regulation of the thickness and consistence of mucus that separates fecal masses from the caecum walls.