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KMID : 0438219720090020241
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Korea University Medical Journal
1972 Volume.9 No. 2 p.241 ~ p.250
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Effect of Antidiuresis and Water Diuresis on Distribution of Electrolyte, Urea and Water in Kidneys of Rabbit
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Abstract
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Renal medulla of mammals presented an osmotic gradient, increasing toward the papilla during hydropenia, was accompanied by a working hypothesis based on a countercurrent multiplier system located in the loops of Henle, in which sodium is pumped out of the ascending limb into the interstitium and recirculated through the descending limb. Much indirect evidences has accumulated since then in favor of this mechanism, such as the early distal urine is always hypotonic, the fluid inside the tip of Henle´s loop has the osmolarity of the urine, the measurement of a high osmotic pressure inside the tip of the vasa recta, etc..
However no direct evidence for a sodium pump located only in the ascending limb has been brought, although some reports that sodium is actively transported in the loop of Henle. Serious objections have been made to such a pumping activity in the ascending limb, since the epithelium have no recognizable difference from the descending limb. The purpose of this study was to make clear on the still unsolved problem of which sodium is pumped by the thin ascending limb or not. On experiments 52 rabbits weighing between 1.5-2.5kg, 17 in control group (urine from 322-800 mOms/kg H₂O), 16 in hydropenia (urine from 984-1530 mOms/kg H₂O), and 19 in water diuresis (urine from 110-298 moms/kg H₂O), were studied.
Hydration for water diuresis was obtained by giving a gavage of 50 ml tap water/kg body weight and dehydration for antidiuresis was obtained by withdrawing of water 48 hours prior to the experimental day. The kidney slices were made for analysis of electrolytes, urea and water.
The results were as follows:-
1. The sodium content showed marked rise in the outer medulla regardless of diuretic state. In the inner medulla sodium content rose toward the papilla during hydropenia but no significant rise observed in water diuresis.
2. The chloride content rose in the same direction as sodium.
3. The potassium content showed no significant changes in the inner medulla in diffierent status of diuresia.
4. The urea content showed very marked rise from the outer medulla toward the papilla during antidiuresis but no significant rise observed throughout the medulla during water diuresis.
5. The water content rose markedly in the outer medulla but no significant change could be observed throughout the inner medulla regardless of diuretic state, However water content in each region of kidney slices in water diuresis was higher than in antiduretic ones.
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