Countercurrent Exchange in Vessels of Renal Medulla

Lassen, N. A.; Longley, James B.

doi:10.3181/00379727-106-26462

Cited by 20 publications

(7 citation statements)

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“…212 As Seholander2 0 and Lassen 12 have indicated, whenever a gradient for a diffusible substance exists between the two limbs, a countercurrent exchanger acts as a barrier to the net transport of that substance along the long axes of the vessels; the effectiveness of the barrier is directly proportional to the diffusibility of 15). Moreover, the effectiveness of the exchange is indicated by the slow medullary deposition of antipyrine, a much less lipidsoluble material with an olive oil/water partition coefficient only l/300th that of krypton.…”

Section: Discussionmentioning

confidence: 99%

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog

Thorburn

Kopald

Herd

et al. 1963

Circulation Research

305

119

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A method has been described for the measurement, by means of Kr 85 , of intrarenal nutrient blood flow distribution in the unanesthetized dog. Injection of the isotope into the renal artery is followed by a multi-exponential disappearance curve which can be obtained by external monitoring with a scintillation detector. In acute experiments autoradiographs have demonstrated that the first exponential component represents cortical blood flow; the second, outer medullary blood flow : the third, inner medullary blood flow; and the fourth, hilar and perirenal fat blood flow. The average cortical blood flow in 65 experiments in five kidneys of four nnanesthetized dogs was 472 ml/100 g/min, the outer medullary 132 ml/100 g/min, and the inner medullary 17 ml/100 g/min. Eighty per cent of the radioactivity was distributed initially to the cortex, 16% to the outer medulla, and 2% to the inner medulla. The hilar and perirenal fat, which receives approximately 2% of the initial radioactivity, was estimated to have a flow rate of 21 ml/100 g/min. In addition, a method for the rapid determination of serial cortical blood flow rates has been described. The importance of these findings has been discussed with reference to the anatomy of the kidney, and to the countercurrent concept as it applies to passive reabsorption of lipid soluble substances, and to the maintenance of an osmotic gradient.

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Section: Discussionmentioning

confidence: 99%

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog

Thorburn

Kopald

Herd

et al. 1963

Circulation Research

305

119

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“…A slow uptake of Ap in the renal papilla previously has been attributed to countercurrent exchange between ascending and descending vasa recta, 18 but no quantifying data are available to evaluate how much the uptake rate is reduced by this mechanism. If one considers the medulla as a whole, medullary blood flow will be underestimated to the extent that Ap concentration in venous blood leaving the medulla is higher than average medullary concentration.…”

Section: Diffusion Vs Flow-limited Uptakementioning

confidence: 99%

Intrarenal distribution of blood flow in rats determined by 125I-iodoantipyrine uptake.

Hope¹,

Clausen²,

Aukland³

1976

Circulation Research

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“…In the normal medulla, the hypertonic environment probably causes blood viscosity to rise due to the crenation of red cells (41) and the threefold increase in protein concentration that occurs in the vasa recta (42)(43)(44)(45)(46). Therefore, medullary hypertonicity may determine, in part, the efferent resistance of the juxtamedullary glomneruli.…”

Section: Methodsmentioning

confidence: 99%

A Micropuncture Study of Postobstructive Diuresis in the Rat

Yarger¹,

Aynedjian²,

Bank³

1972

J. Clin. Invest.

100

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A B S T R A C T In order to investigate the syndrome of postobstructive diuresis, clearance and micropuncture studies were carried out in rats after relief of 24 hr of bilateral (BUL) or unilateral (UUL) ureteral ligation. In rats with BUL, a striking diuresis and natriuresis occurred when the obstruction to one kidney (the experimental kidney) was relieved. The results were not influenced by administration of vasopressin or d-aldosterone. Whole kidney clearances of inulin and p-aminohippuric acid (PAH) in the experimental kidney were reduced to 10% and 20% of normal, respectively. Superficial nephron inulin and PAH clearances were also reduced, but only to 40% and 45%, respectively. These findings suggest a heterogeneity of nephron function in which deep nephrons were functioning poorly or not at all. To investigate the site of impaired tubular reabsorption in the surface nephrons, absolute and fractional water reabsorption was measured. Absolute reabsorption was found to be decreased all along the nephron. Fractional reabsorption in proximal tubules was normal, as indicated *by an average endproximal tubular fluid per plasma inulin (TF/Pi.) of 2.16 vs. 2.30 in controls. TF/Pri was markedly decreased in distal tubules (2.91 vs. 8.02) and final urine (5.56 vs. 263). These observations indicate that the major sites of impaired sodium reabsorption leading to the diuresis were beyond the proximal tubule.

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Countercurrent Exchange in Vessels of Renal Medulla

Cited by 20 publications

References 0 publications

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog

Intrarenal distribution of blood flow in rats determined by 125I-iodoantipyrine uptake.

A Micropuncture Study of Postobstructive Diuresis in the Rat

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Countercurrent Exchange in Vessels of Renal Medulla

Cited by 20 publications

References 0 publications

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton 85 in the Unanesthetized Dog

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton 85 in the Unanesthetized Dog

Intrarenal distribution of blood flow in rats determined by 125I-iodoantipyrine uptake.

A Micropuncture Study of Postobstructive Diuresis in the Rat

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Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog

Intrarenal Distribution of Nutrient Blood Flow Determined with Krypton ⁸⁵ in the Unanesthetized Dog