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KMID : 0438219750120030799
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Korea University Medical Journal
1975 Volume.12 No. 3 p.799 ~ p.808
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Effect of abdominal aorta constriction on distribution of osmolarity, electrolytes, urea, water and hemodynamics in the rabbit kidney
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Abstract
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The long loop nephrons, descending deep into the medulla, arise primarily from the juxtamedullary region of the cortex. The larger the number of these nephrons, the greater is the concentration capacity of the animal. The proximal and distal convoluted tubules of all nephrons are confined to the isotonic cortex, where the distal convoluted tubules terminated in collecting ducts which extend down through the medulla. The blood supply of renal medulla is composed entirely of postglomerular vessels derived from the juxtamedullary glomeruli. These vessels (vasa recta) descend into the medulla, take a heparin turn, and ascend to their level of origin. Their capillaries lie in the closest proximity with the loop of Henle and collecting ducts.
There appears to be general agreement that the loop of Henl.e functioning as a countercurrrent multiplier system creates the osmolar gradient of the renal medulla, essential to the production of a hypertonic urine, while the vasa recta acting as a countercurrent exchanger prevents the dissipation of the osmotic gradient of the renal medulla. Several investigators have suggested that intrarenal hemodynamic alterations caused by hemorrhagic hypotention, namely more severe decrement of glomeruIar filtration than medullary blood flow, may affect a depletion of the medullary osmotic gradient. However, less information is available concerning the effect on the medullary osmolar concentration of renal hemodynamic alterations following decrements of renal arterial pressure.
The purpose of this study was to evaluate the effect of decreased renal arterial pressure on the medullary osmotic gradient in rabbit kidney.
-On the experiments 40 rabbits were composed that 20 of them as normal control group, and the
others as the experimental.
In the latter, the abdominal aorta were constricted for about half in outer diameter at the 1.0cm above the origin of renal artery.
The results were as follows:
(1) The renal medullary osmolar concentration showed marked decrement but no osmolar gradient in the abdominal aorta constricted group than in the normal control.
(2) The renal medullary sodium and urea concentration or content showed further decrease in the abdominal aorta constricted group than in the normal control.
(3) The glomerular filtration rate and medullary plasma flow as well as the total renal plasma flow and renal cortical flow were all decreased, however the glomerular filtration rate was further decreased in the abdominal aorta constricted group than in the normal control.
(4) The urine was not concentrated in the abdominal aorta constricted group than in the normal control.
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