ISSN:
1432-2013
Keywords:
Cl− secretion
;
Na+ absorption
;
CAMP
;
exocrine secretion
;
Cl− channel
;
Na+ channel
;
colon
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Previously we have shown that mid crypt cells of corticoid treated rats possess an amiloride inhibitable Na+ conductance (NAC) and show an increased Cl− conductance when stimulated by prostaglandin or the second messenger CAMP. The NAC is supposed to determine the magnitude of NaCl absorption. The Cl− conductance defines the magnitude of NaCl secretion. In the present whole cell (WC) patch clamp study we have examined whether the amiloride (3 μmol/l) inhibitable NAC is downregulated when the Cl− conductance is increased by forskolin (5 μmol/l, n = 20) or the phosphodiesterase inhibitor IBMX (1 mmol/l, n = 5). Under control conditions the amiloride inhibitable NAC was 2.7 ± 0.4 nS. Forskolin depolarized the voltage from -58 ± 2.0 to-48 ± 1.9 mV and enhanced the WC conductance by 3.25 ± 0.6 nS in these cells. The amiloride inhibitable NAC was reduced to 0.38 ± 0.2 nS. These data confirm that forskolin enhances the Cl− conductance in these cells and they show for the first time that the Na+ conductance is reduced simultaneously. Thus the cells are able to change the direction of NaCl transport from absorption to secretion.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02332187
