Potassium transport across renal distal tubules during acid-base disturbances

Malnic, Gerhard; Aires, Margarida de Mello; Giebisch, Gerhard

doi:10.1152/ajplegacy.1971.221.4.1192

Cited by 111 publications

(57 citation statements)

References 40 publications

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“…The finding of progressive reabsorption of potassium along the distal convoluted tubule in normal rats is in agreement with the observations of Marsh, Ullrich, and Rumrich (6), but conflicts with several studies by Malnic, Klose, Giebisch, and de Mello Aires (7)(8)(9). These latter authors have reported that under a variety of different experimental conditions, tubular fluid potassium concentration rises at the end of the distal tubule to levels severalfold higher than plasma concentration, and that there is net addition of potassium to the tubular fluid by the distal convoluted tubule.…”

Section: Discussionsupporting

confidence: 89%

“…These latter authors have reported that under a variety of different experimental conditions, tubular fluid potassium concentration rises at the end of the distal tubule to levels severalfold higher than plasma concentration, and that there is net addition of potassium to the tubular fluid by the distal convoluted tubule. Only under conditions of a low potassium diet (7), or severe metabolic or respiratory acidosis (9) did net reabsorption of potassium occur in the distal tubule. The reason for the difference between our observations and those of Malnic and co-workers is not clear, but several possibilities can be considered.…”

Section: Discussionmentioning

confidence: 99%

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A Micropuncture Study of Potassium Excretion by the Remnant Kidney

Bank¹,

Aynedjian²

1973

J. Clin. Invest.

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A B S T R A C T In order to study the mechanism of enhanced potassium excretion by the remaining nephrons of the remnant kidney, micropuncture and clearance experiments were carried out in rats after surgical ablation of 3/4 of the total renal mass. The potassium intake in all animals was approximately 5 meq/day. Animals were studied 24 h and 10-14 days after 3/4 nephrectomy. Balance measurements in the chronic animals before micropuncture study indicated that 24 h K+ excretion by the remnant kidney was equal to that of the two kidneys before ablation of renal mass. Measurements of distal tubular inulin and potassium concentrations revealed progressive reabsorption of potassium in this segment of the nephron in both the 24-h and chronic 3/4-nephrectomized rats, as well as in normal control rats. A large increase in tubular fluid potassium content occurred between the end of the distal tubule and the final urine in the 3/4-nephrectomized rats, but not in the normal controls. These observations suggest that the segment of the nephron responsible for enhanced potassium excretion by remaining nephrons was the collecting duct.In additional experiments, potassium was completely eliminated from the diet of chronic 3/4-nephrectomized rats before micropuncture study. In these animals, no addition of K+ occurred beyond the distal tubules. Normal rats infused with 0.15 M KCl to acutely elevate serum K+ concentration, demonstrated reabsorption of K+ in the distal tubule and a large addition of K+ to the urine beyond the distal tubule.We conclude that the collecting duct is the major site of regulation of urinary potassium excretion in normal rats and is responsible for the adaptation to nephron loss by the remnant kidney.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 99%

A Micropuncture Study of Potassium Excretion by the Remnant Kidney

Bank¹,

Aynedjian²

1973

J. Clin. Invest.

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“…Finally, potassium handling has been suggested to be another regulator: potassium loading in dogs increases K secretory fluxes and suppresses the rate of distal nephron hydrogen ion secretion (4). However, in rat distal tubule micropuncture studies, no evidence of a reciprocal relationship between distal tubular K and hydrogen ion secretory rates could be obtained (8).…”

Section: Introductionmentioning

confidence: 95%

An in vivo microperfusion study of distal tubule bicarbonate reabsorption in normal and ammonium chloride rats.

Levine¹

1985

J. Clin. Invest.

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For many years it has been thought that distal nephron hydrogen ion secretion can be importantly modulated by factors such as sodium delivery, sodium avidity, and potassium stores. Free flow micropuncture studies have also indicated that the rate of bicarbonate delivery may also alter the rate of bicarbonate reabsorption. The present studies were undertaken to examine possible luminal influences on total CO2 reabsorption in microperfused distal tubules in the rat in vivo. Tubules from normal and acidotic rats were perfused with five solutions in a manner that induced changes in bicarbonate load, sodium and potassium fluxes (JNa, JK), and luminal sulfate concentration. In each collected perfusate, simultaneous analyses were undertaken to determine water reabsorption, Na, and K concentrations using graphite furnace atomic absorption spectroscopy and total CO2 by microcalorimetry. Using factorial analysis of covariance to account for confounding effects on total CO2 flux (Jwco2) such as water reabsorption, distal tubules of acidotic rats reabsorbed CO2 in the range of 50-112 pmol * min-' -mm-'. These Jwo, values were not significantly correlated with HCO3 load, JNa, or JK despite changes in the latter from net reabsorption to net secretion. Distal tubules of rats with normal acid-base status had Jtco2 values which were neither significantly different from zero nor correlated with changes in JK and JNa. Further, doubling the load from 250-500 pmol/min (by doubling the perfusion rate of 25-mM HCO3 solutions) did not stimulate JC02 in these normal animals. Accordingly, these acute in vivo microperfusion studies indicate for the first time that neither load nor potassium or sodium fluxes are important modulators of distal tubule bicarbonate reabsorption.

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“…The isolated cortical collecting duct of the rabbit has been shown capable of adding potassium to the urine (21), as has the papillary collecting duct of the hamster (22). Several studies by Malnic and Giebisch and their associates in rats, however, failed to demonstrate net addition of potassium to the urine beyond the distal convoluted tubule (7,23), and Diezi et al were unable to show net potassium secretion consistently in the papillary collecting duct of the rat (24). More recently, Bank and Aynedjian have been able to demonstrate the addition of potassium to the final urine at a point distal to the micropunctured cortical distal convolution in partially nephrectomized rats subjected to potassium loads.…”

Section: Resultsmentioning

confidence: 99%