Transductal fluxes of Na, K, and water in the human eccrine sweat gland.

MANGOS, JOHN. Transductal fluxes of Na, K, and water in the human eccrine sweat gland. Am. J. Physiol. 224(5): 1235-1240. 1973.--The bidirectional fluxes of Na, the net influx of K, and the net fluxes of water were studied in the human sweat duct in vitro by free-flow microperfusion with sweat resembling the primary secretory fluid and by microanalysis of the fluid samples obtained. Full-thickness skin explants were mounted in a specially designed chamber and single sweat ducts were perfused. The transductal water fluxes were small. At perfusion rates of 17.3, 12.7, and 5.2 nl/duct min, the net Na reabsorption was 0.418, 0.504, and 0.584 nEq/rnin, whereas the calculated Na backdiffusion was 0.208, 0.190, and 0.049 nEq/min, respectively. These, opposing changes resulted in constant values of total Na reabsorption. Net K influx was a small fraction of Na reabsorption with values of 0.047, 0.070, and 0.043 nEq/ min at the three perfusion rates. Addition of ouabain, 5 X 10-S M, to the bath medium decreased both the Na reabsorption and K influx. JOHN MANGOS Department of Pediatrics, University of Wisconsin Medical School, Mudison, Wisconsin 53706