Aldosterone Stimulates K Secretion across Mammalian Colon Independent of Na AbsorptionProceedings of the National Academy of Sciences of the United States of America
AbstractK transport across guinea pig (Cavia porcellus) distal colon was measured in vitro using isotopically determined unidirectional fluxes. Aldosterone stimulated electrogenic Na absorption, as measured by amiloride-sensitive short-circuit current (Isc), and reduced net K absorption from +2.5 ± 0.2 µEq/cm2 per hr to +0.8 ± 0.3 µEq/cm2 per hr (mean ± SEM). Amiloride addition to the mucosal solution did not enhance net K absorption, as expected if inhibiting active Na absorption would reduce active K secretion as in the distal nephron. The amiloride-insensitive Isc was -1.0 ± 0.2 µEq/cm2 per hr (mean ± SEM) and was inhibited by mucosal addition of Ba, a K channel blocker. Addition of bumetanide to the serosal solution also inhibited this negative Isc, and K transport returned to the control level of net absorption. Thus, the amiloride-insensitive, negative Isc is consistent with active K secretion stimulated by aldosterone. This stimulation of an active K secretory pathway by aldosterone occurred without altering the active K absorption pathway that also is present. These results indicate that the aldosterone-stimulated K secretory pathway operates independently of the amiloride-sensitive Na absorption pathway, which also is stimulated by aldosterone.
Citation InformationGerhard Rechkemmer and Dan R. Halm. "Aldosterone Stimulates K Secretion across Mammalian Colon Independent of Na Absorption" Proceedings of the National Academy of Sciences of the United States of America Vol. 86 Iss. 1 (1989) p. 397 - 401 ISSN: 10916490
Available at: http://works.bepress.com/dan_halm/32/