The APS Journal Legacy Content is the corpus of 100 years of historical scientific research from the American Physiological Society research journals. This package goes back to the first issue of each of the APS journals including the American Journal of Physiology, first published in 1898. The full text scanned images of the printed pages are easily searchable. Downloads quickly in PDF format.

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We are indebted t o Merck and CO., Inc., Rahway, N. J., for the supply of crystalline B vitamins, and to the Abbott Laboratories, North Chicago, Ill., for the generous supply of haliver oil.

A method for chronic continuous urine collection from the two separate kidneys is described. In successful preparations, presumably normal urine may be collected for at least several weeks. The excretions from the two sides are compared and are quite similar, with differences being greatest for sodium excretion. For a variable period following unilateral renal denervation excretion of water, sodium, osmotically active solutes and creatinine may be greater from the denervated kidney than the normal. The differences usually decrease markedly or vanish with time. Any chronic influence of renal denervation in the normal resting dog on sodium excretion, if present, is minor as compared with that of other factors such as mechanically induced unilateral slight fall in GFR, which may result in diminution of sodium output of constricted kidney to only 10 or 20% that of unmolested kidney. Renal vascular sympathetic tone in the resting untraumatized dog is very small or absent within the limits of experimental error.

A nunber of observers have reported that acute reduction of glomerular filtration rate (GFR) in experimental animals induces a considerable fall in renal excretion of sodium and water. Chronic constriction of one renal artery is followed by persistent fall in salt and water excretion by that kidney (1). In man, change from the recumbent to the erect position is followed by a considerable fall in urinary flow and sodium excretion and by small decrease in inulin and exogenous or endogenous creatinine clearances (2-4). The above findings were on subjects not in maximal water diuresis. In human subjects with a large water load who had been sitting for four to eight hours, change to recumbency was followed by increase in urine flow, sodium excretion and sodium urinary concentration while creatinine U/P ratios fell and endogenous creatinine clearance rose slightly (5).Whether more nearly complete reabsorption of sodium and water following maneuvers reducing GFR is accomplished in the proximal or the distal segment of the tubule is not certain. Pitts and Duggan (6, 7) inferred that organic mercurial diuretics depress the distal reabsorption of sodium, and after observing that aortic constriction produced marked fall in sodium excretion even after administration of a large dose of Mercuhydrin®: in dogs they concluded that the increased sodium and water reabsorption resulting from fall in GFR takes place in the proximal segment. The inference that mercurial diuretics act solely distally has been supported (8) and rejected (9,10) and the loci of the more complete reabsorption remain unidentified.As has been reviewed previously (4) most workers have found a fall in GFR with postural change from the horizontal to a head-up tilt or standing.We here report the effects of postural change on the excretion of water, sodium, creatinine and os- motically active solutes in normal human subjects in maximum water diuresis. We have attempted to localize within the nephron some of the changes observed, using the following assumptions: 1) Distal water reabsorption is abolished in maximum water diuresis with the subject at ease, recumbent or standing (11). 2) Proximal reabsorption is isotonic (12-15). Evidence for the first assumption is that urine flow in maximal water diuresis or in complete diabetes insipidus about equals the volume of fluid leaving the proximal tubules, as estimated by observations on proximal fluid samples obtained by micropuncture (13).If it should be found that the percentage fall in water excretion on changing from recumbency to standing with subjects in maximal water diuresis is significantly greater than the percentage fall in GFR it would follow that the percentage of filtered water reabsorbed proximally is increased on standing. Since proximal reabsorption is considered as isotonic, the percentage of filtered sodium reabsorbed proximally is also increased. If it should further be found that urine and plasma osmolarity remain unchanged, free water clearance also shows a greater percentage fall than does GFR. T...