Die Abh�ngigkeit des O2-Verbrauchs der Niere von der Na-R�ckresorption

Deetjen, P.; Kramer, Kürt

doi:10.1007/bf00361632

Cited by 140 publications

(35 citation statements)

References 14 publications

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“…Considering the close correlation between tubular sodium transport and oxygen consumption in the kidney (22) and the fact that proximal tubules constitute the bulk of cortical tissue (23), these data constitute further evidence that proximal tubular sodium reabsorption is decreased in hypothyroid rats. Estimation of the absolute amounts of sodium delivered out of the end proximal tubule in the present study indicate that these were similar in the control (2.0 nEq/min) and the hypothyroid animals (1.8 nEq/min).…”

Section: Methodssupporting

confidence: 55%

Renal handling of sodium and water in the hypothyroid rat

Michael¹,

Barenberg²,

Chavez³

et al. 1972

J. Clin. Invest.

104

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A B S T R A C T Hypothyroid rats were examined with conventional renal clearance and micropuncture techniques to elicit the mechanism and site within the nephron responsible for the increased salt and water excretion observed in these animals. When compared with age-matched control rats, a decrease in inulin clearance of 30% (P < 0.001) and in Hippuran clearance of 32% (P < 0.005) was observed in the hypothyroid rats. Absolute excretion of sodium and water was increased 3-fold (P < 0.02) and 2-fold (P < 0.025),. respectively, while fractional excretion of sodium and water was increased 4.3-fold (P < 0.02) and 2.9-fold (P < 0.05), respectively, in the hypothyroid animals.Fractional proximal reabsorption of sodium as assessed from proximal tubular fluid to plasma ratios of inulin ([TF/P]IN) was found to be decreased by 28% (P < 0.001) in the hypothyroid rats. Superficial single nephron filtration rate was reduced proportionately to the decrease in total filtration rate in the hypothyroid rats. These data indicate that the proximal tubule is one of the sites of diminished sodium and water reabsorption in the hypothyroid rat. The data also suggest that the observed decrease in glomerular filtration rate in the hypothyroid animals is not caused by a decrease in the number of functioning nephrons and that the observed increase in sodium and water excretion is not caused by a redistribution of filtrate from juxtamedullary to super-

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Section: Methodssupporting

confidence: 55%

Renal handling of sodium and water in the hypothyroid rat

Michael¹,

Barenberg²,

Chavez³

et al. 1972

J. Clin. Invest.

104

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“…It should be remembered, however, that reduction of renal perfusion flow not only causes a reduction of renal oxygen delivery but also decreases the tubular sodium load and thereby locally alters renal oxygen consumption [4].…”

Section: Discussionmentioning

confidence: 99%

Oxygen-dependent erythropoietin production by the isolated perfused rat kidney

et al. 1991

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Abstract. In this study we have investigated the role of oxygen delivery and of classic second messengers on erythropoietin production by the isolated perfused rat kidney. We found that the rat kidney was capable of de novo synthesis of erythropoietin. The erythropoietin production rate was inversely related to the oxygen pressure in the perfusate and increased from 0.17 to 1.85U erythropoietin h -1 g kidney -z when arterial PO2 was lowered from 500 mmHg to 30 mmHg. Addition of forskolin (10 gM) and 8-bromo-cGMP (100 gM) to the perfusate elicited significant effects on the renal vascular resistance, but had no significant effect on erythropoietin production. Hypoxia-induced erythropoietin formation, however, was blocked by calmidazolium (1 gM) and W-7 (10 lxM), two structurally different putative calmodulin antagonists. Calmidazolium and W-7 had no effect on other functional parameters of the isolated perfused rat kidney such as flow rate, glomerular filtration rate or sodium reabsorption. Our findings suggest that the oxygensensing mechanism that controls renal erythropoietin production is primarily located in the kidney itself. A cap cium/calmodulin-dependent cellular reaction could be involved in the signal transduction process.

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“…The fairly homogeneous reduction of renal blood flow observed during hemorrhagic hypotension would not be expected to produce deleterious cortical hypoxia, in the first place because tubular functions and renal oxygen consumption are well maintained at low arterial oxygen saturation (43), and in the second place because the renal oxygen requirement falls markedly with reduction of glomerular filtration rate and tubular salt reabsorption (44,45). This conclusion agrees well with the finding of Munck, Lassen, Deetj en, and Kramer (46), that both cortical and renal venous oxygen saturation remained relatively high even during severe hemorrhagic hypotension, and is further supported by the survival of all dogs in the present series without evidence of renal failure.…”

Section: Discussionmentioning

confidence: 99%

Effect of hemorrhage and retransfusion on intrarenal distribution of blood flow in dogs

Aukland¹,

Wolgast²

1968

J. Clin. Invest.

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A B S T R A C T Distribution of intrarenal blood flow was studied in 12 dogs anesthetized with Nembutal. Medullary blood flow was estimated by local clearance of hydrogen gas from the outer medulla measured polarographically with needleshaped platinum electrodes, and by local clearance of 85Kr and mean transit time of 32P-labeled erythrocytes measured with a small semiconductor detector placed in the outer medulla. Cortical blood flow was estimated from cortical red cell transit time and from total renal blood flow measured by electromagnetic flowmeter.Bleeding to a mean arterial pressure of 50-65 mm Hg in the course of 8-20 min reduced cortical and medullary blood flow on the average to the same extent. In half of the experiments both cortical and medullary blood flow were reduced proportionately less than mean arterial pressure during the first half hour of bleeding. Maintenance of mean arterial pressure at 50-65 mm Hg in all cases led to progressive reduction of both cortical and medullary blood flow, out of proportion to the reduction of arterial pressure. A two step bleeding procedure used in two experiments also led to uniform reduction of renal blood flow. Reinfusion of blood after 2-3 hr of hypotension increased total renal blood flow to an average of 82% and outer medullary hydrogen clearance to an average of 92%o of control values. All dogs survived the experiment without evidence of renal failure.

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Die Abh�ngigkeit des O2-Verbrauchs der Niere von der Na-R�ckresorption

Cited by 140 publications

References 14 publications

Renal handling of sodium and water in the hypothyroid rat

Renal handling of sodium and water in the hypothyroid rat

Oxygen-dependent erythropoietin production by the isolated perfused rat kidney

Effect of hemorrhage and retransfusion on intrarenal distribution of blood flow in dogs

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