Intestinal iodide secretion and its dependence upon mucosal I- permeability.
Iodide secretion across different regions of rat small intestine has been investigated in vitro using the standard Wilson-Wiseman technique. Net I- secretion was observed along the entire small intestine, being significantly higher in the central region. Anaerobic conditions, ouabain (2 mM) and Na+ free Ringer solution prevented net I- secretion, whilst both theophylline (1 mM) and carbachol (0,1 mM) enhanced the observed basal intestinal I- secretion. Furthermore, Ca2+-deprived bathing solutions significantly reduced intestinal I- secretion. Epithelial I- uptake from both mucosal and serosal sides was measured by using a Ussing-type chamber technique. The initial rate of I- uptake across the mucosal membrane was significantly higher in the central region than in the proximal part of rat small intestine. No significant differences were observed in the rate of I- uptake from the serosal side. These studies suggest that mucosal I- permeability might determine the direction of net I- intestinal transport and that cytosolic Ca2+ may be a physiological regulator of intestinal I- transport.
D019297:2,4-Dinitrophenol; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D004140:Dinitrophenols / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D007454:Iodides / Q000378:metabolism*; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012636:Secretory Rate / Q000187:drug effects; D012964:Sodium / Q000494:pharmacology; D013806:Theophylline / Q000494:pharmacology
D004140:Dinitrophenols; D007454:Iodides; D010042:Ouabain; D002217:Carbachol; D012964:Sodium; D013806:Theophylline; D019297:2,4-Dinitrophenol