English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In the presence of antidiuretic hormone (ADH), the concentration of the urine is usually related inversely to the excreted osmotic load. When solute excretion is increased by infusion of relatively nonreabsorbable solute, urine concentration falls toward plasma concentration. Maximum urine concentrations are achieved only when solute excretion is very low. In the dog, the highest urine osmolalities, in the range of 1,800 to 2,200 mOsm. per Kg. H2O, occur when solute excretion is about 200 to 300 /%Osm. per minute, If urine concentration and solute excretion are inversely related even at the lowest solute loads, one would expect an increase in urine concentration when spontaneously low osmotic loads are decreased further by lowering the glomerular filtration rate (GFR). On the other hand, if the highest urine concentrations seen under spontaneous conditions represent the maximum osmolality which the kidney can achieve (1), further reductions in solute excretion would not be expected to result in increased urine concentration. Under certain circumstances in the present studies, maximum spontaneous urine concentrations did increase when the GFR was reduced, in conformity with the first view described. However, neither of these alternatives explains the findings of Leaf, Kerr, Wrong and Chatillon (2), confirmed in this paper, that urine osmolality often falls when the GFR is reduced in the presence of ADH. Recently, it has been postulated (3, 4) that urine is made hypertonic to plasma by equilibration with hypertonic interstitial fluid in the medulla of the kidney. This paper presents data consistent with the view that the fall in urine concentration when GFR is reduced is due to de-

EFFECTS OF REDUCED GLOMERULAR FILTRATION ON URINE CONCENTRATION IN THE PRESENCE OF ANTIDIURETIC HORMONE*