The formation of urine in the amphibian and mammalian kidney

Abstract

THE present communication is concerned with the function of the amphibian and the mammalian kidney as revealed by intravital microscopic examination of its responses to certain dyes and drugs, The aim of the experiments has been to discover whether the tubules have a secretory function in addition to their reabsorptive activity, and if so, whether this is a normal function of the proximal convoluted tubules or one which comes into play only under unusual conditions.

The Site of Acidification of Urine in the Frog's and Rat's Kidney

“…The preliminary urine is acidified to a certain degree in the proximiial tubules. Both findings are in complete agreement with the results of Ellinger and Hirt [1929 b] oil German Rana esculenta in summer, and with those of Ellinger [1934Ellinger [ a, 1940 on Hungarian Rana esculenta at all seasons in England; the second, relating to the proximal tubules, appears to be entirely opposed to the results of Montgomery andPierce [1935, 1937] and of Richards [1938]. This contradiction may, however, be only apparent.…”

“…They were anaesthetised for the experiment by intraperitoneal injection of 30 mg. of chloralhydrate per 100 g. The kidneys were exposed according to the methods described in detail by Ellinger and Hirt [1929 a] and by Ellinger [1940]. In rats glomeruli and distal tubules were brought to the surface by taking a shaving from the surface of the kidney in a preliminary operation carried out under ether ansesthesia.…”

“…Hirt, 1939;Ellinger, 1939]. Ellinger [1934Ellinger [ a, 1940 on Hungarian Rana esculenta in this country during all seasons. Only a certain proportion of the glomeruli were active, and changes in activity of the glomeruli were not frequent.…”

“…In their experiments on Necturus maculosus direct measurements of the pH were made by other methods in the lower urinary tract, and it is evident that in all but one experiment reported the urine in the bladder was not more acid than pH 6-0. The urine in the bladder of summer frogs in the experiments of Ellinger and Hirt [1929 b], Ellinger [1934Ellinger [ a, 1940, and in those now reported, was far more acid [between pH 5*5 and 4.5]. The results of experiments carried out by Montgomery and Pierce [1937] on artificially perfused surviving kidneys of frogs cannot be accepted as convincing, since Ellinger and Hirt [1929 b] have shown that the artificially perfused frog's kidney differs considerably from that of a living frog with regard to its staining with fluorescein and the pH of its different portions.…”

“…But no direct evidence was furnished for this assumption. If the body is suddenly overloaded with acid by the injection of large amounts of acid salts, either intravenously or into the lymph sac, an acid urine is excreted very rapidly through the epithelium of the proximal tubules [Ellinger and Hirt, 1931;Ellinger, 1934Ellinger, a, 1940. This rapid excretion can be followed directly.…”