Abstract:
Previously we have shown that mid crypt cells of corticoid treated rats possess an amiloride inhibitable Na+ conductance (NAC) and show an increased CI- conductance when stimulated by prosta-glandin or the second messenger cAMP. The NAC is supposed to determine the magnitude of NaCl absorption. The CI- conductance defines the magnitude of NaCI 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 CI- 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.
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Ecke, D., Bleich, M. & Greger, R. The amiloride inhibitable Na+ conductance of rat colonic crypt cells is suppressed by forskolin. Pflügers Arch. 431, 984–986 (1996). https://doi.org/10.1007/s004240050095
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DOI: https://doi.org/10.1007/s004240050095