title: Effects of adrenal steroids on Na transport in the lower intestine (coprodeum) of the hen.
abstract: The influence of adrenal steroids on sodium transport in hen coprodeum was investigated by electrophysiological methods. Laying hens were maintained on low-NaCl diet (LS), or on high-NaCl diet (HS). HS hens were pretreated with aldosterone (128 micrograms/kg) or dexamethasone (1 mg/kg) before experiment. A group of LS hens received spironolactone (70 or 160 mg/kg, for three days). The effects of these dietary and hormonal manipulations on the amiloride-sensitive part of the short-circuit current were examined. This part is in excellent agreement with the net Na flux, and therefore a direct electrical measurement for Na transport. After depolarizing the basolateral membrane potential with a high K concentration, the apical Na permeability and the intracellular Na activity were investigated by current-voltage relations for the different experimental conditions. Plasma aldosterone concentrations (PA) were low in HS hens, dexamethasone-treated HS hens and spironolactone-treated LS hens (less than 70 pM). In contrast LS hens and aldosterone-treated HS hens had a PA concentration of 596 +/- 70 and 583 +/- 172 pM, respectively. LS diet (chronic stimulation) had the largest stimulatory effect on Na transport and apical Na permeability. Hormone-treated animals had three- to fourfold lower values. Spironolactone supply in LS hens decreased Na transport and apical Na permeability about 50%. The results provide evidence that both mineralo- and gluco-corticoids stimulate Na transport in this tissue by increasing the apical Na permeability. Quantitative differences between acute and chronic stimulation reveal a secondary slower adaptation in apical membrane properties.
mesh_terms: D000450:Aldosterone / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002645:Chickens; D003907:Dexamethasone / Q000494:pharmacology*; D004039:Diet, Sodium-Restricted; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D013148:Spironolactone / Q000494:pharmacology
chemical_list: D013148:Spironolactone; D000450:Aldosterone; D003907:Dexamethasone; D012964:Sodium