Article date: December 2000
By: Brian McNamara, Desmond C Winter, John Cuffe, Colm Taylor, Gerald C O'Sullivan, Brian J Harvey in Volume 131, Issue 7, pages 1373-1378
We investigated the effect of oestradiol on basolateral potassium channels in human colonic epithelium.
Ion transport was quantified using short circuit current (Isc) measurements of samples mounted in Ussing chambers. Serosal K transport was studied using nystatin permeabilization of the apical membrane. Intracellular pH changes were quantified using spectroflouresence techniques.
Experiments were performed with either 10 nM or 1 μM Ca2+ in the apical bathing solution. With 10 nM Ca2+ in the apical bathing solution addition of oestradiol (1 nM) to the basolateral bath produced a rapid increase in current (ΔIK=11.2±1.2 μA.cm−2, n=6). This response was prevented by treatment of the serosal membrane with tolbutamide (1 μM). With 1 μM Ca2+ in the apical bathing solution addition of oestradiol produced a rapid fall in current (ΔIK=−12.8±1.4μA.cm−2), this response was prevented by treatment of the basolateral membrane with tetra‐pentyl‐ammonium (TPeA). These responses were rapid and occurred independently of protein synthesis.
Inhibition of basolateral Na+/H+ exchange with either amiloride or a low sodium bathing solution prevented this response. These responses were prevented by inhibition of protein kinase C (PKC) with bis‐indolyl‐maleimide.
Oestradiol (1 nM) produced a rapid intracellular alkanization (mean increase=0.11 pH units; n=6; P<0.01).
These results suggest that oestradiol rapidly modulates serosal K transport in human colon. These effects depend upon intact Na+/H+ exchange and protein kinase C. We propose a non‐classical, possibly membrane linked, mechanism for oestradiol action in human colonic epithelium.
We investigated the effect of oestradiol on basolateral potassium channels in human colonic epithelium.
Ion transport was quantified using short circuit current (Isc) measurements of samples mounted in Ussing chambers. Serosal K transport was studied using nystatin permeabilization of the apical membrane. Intracellular pH changes were quantified using spectroflouresence techniques.
Experiments were performed with either 10 nM or 1 μM Ca2+ in the apical bathing solution. With 10 nM Ca2+ in the apical bathing solution addition of oestradiol (1 nM) to the basolateral bath produced a rapid increase in current (ΔIK=11.2±1.2 μA.cm−2, n=6). This response was prevented by treatment of the serosal membrane with tolbutamide (1 μM). With 1 μM Ca2+ in the apical bathing solution addition of oestradiol produced a rapid fall in current (ΔIK=−12.8±1.4μA.cm−2), this response was prevented by treatment of the basolateral membrane with tetra‐pentyl‐ammonium (TPeA). These responses were rapid and occurred independently of protein synthesis.
Inhibition of basolateral Na+/H+ exchange with either amiloride or a low sodium bathing solution prevented this response. These responses were prevented by inhibition of protein kinase C (PKC) with bis‐indolyl‐maleimide.
Oestradiol (1 nM) produced a rapid intracellular alkanization (mean increase=0.11 pH units; n=6; P<0.01).
These results suggest that oestradiol rapidly modulates serosal K transport in human colon. These effects depend upon intact Na+/H+ exchange and protein kinase C. We propose a non‐classical, possibly membrane linked, mechanism for oestradiol action in human colonic epithelium.
British Journal of Pharmacology (2000) 131, 1373–1378; doi:10.1038/sj.bjp.0703714
DOI: 10.1038/sj.bjp.0703714
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