Effects of osmotic diuresis on sodium reabsorption and oxygen consumption of kidney

FG Knox, JS Fleming… - American Journal of …, 1966 - journals.physiology.org
FG Knox, JS Fleming, DW Rennie
American Journal of Physiology-Legacy Content, 1966journals.physiology.org
KNOX, FG, JS FLEMING, AND DW RENNZE. E $ ects of osmotic diuresis on sodium
reabsorption and oxygen consumption of kidney. Am. J. Physiol. 210 (4): 751-759. x966.-
Filtered and excreted sodium and renal 0, consumption were measured simultaneously in
anesthetized dogs undergoing diuresis induced by water or Ringer solution (control),
mannitol, and ethacrynic acid. Under control conditions the regression of total renal qZ
consumption, vo,, on net sodium reabsorption, T Na, was: VO,= 0.034(SE 0.005) T Na+ …
KNOX, FG, J. S. FLEMING, AND D. W. RENNZE. E $ ects of osmotic diuresis on sodium reabsorption and oxygen consumption of kidney. Am. J. Physiol. 210 (4): 751-759. x966.-Filtered and excreted sodium and renal 0, consumption were measured simultaneously in anesthetized dogs undergoing diuresis induced by water or Ringer solution (control), mannitol, and ethacrynic acid. Under control conditions the regression of total renal qZ consumption, vo,, on net sodium reabsorption, T Na, was: VO,= 0.034(SE 0.005) T Na+ 0.013 (SE o. o45), indicating a Na/O, ratio of 2g Eq Na/mole 0,, SE 3. Mannitol diuresis decreased T Na 34%; but 30, was not affected. Further reduction of TNa during sustained mannitol diuresis by elevation of ureteral pressure or by hemorrhage indicated a new regression Of 90, on TNa: 90,= 0.051 (. OOG) TNa+ 0.042 (0.023). Na/O, app arently decreased to 20 Eq Na/mole 0, zt 3. Low Na/O, was not considered due to heterogeneity of Na/O, between proximal and distal epithelium since selective blockade of distal sodium reabsorption by ethacrynic acid did not affect the normal Na/OZ. Increased thermodynamic work of Na transport would decrease Na/O, uniformly in both proximal and distal tubules, or there could be active reabsorption of a nonmeasurable quantity of sodium that enters tubular fluid by net inward diffusion during osmotic diuresis, causing an apparent but not real decrease in Na/O,. Though anatomical localization of such Na cycling is not possible at present, the thick ascending limb of Henle’s loop is considered a likely site of extra-active Na transport. Thus, the latter theory implicates the outer medulla as a site of greatly increased 0, utilization during osmotic diuresis. sodium transport; Na/O, ratio; mannitol diuresis; ethacrynic acid
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