The Means of Distinguishing between Hydrogen Secretion and Bicarbonate Reabsorption: Theory and Applications to the Reptilian Bladder and Mammalian Kidney

Brodsky, William A.; Schilb, Theodore P.

doi:10.1016/s0070-2161(08)60186-0

Cited by 20 publications

(13 citation statements)

References 59 publications

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“…The results can be rationalized on either 3This point is dispuited. Brodsky and Schilb (17) contend that acidification is the result of direct bicarboniate absorption not linked to hydrogeni ion secretion. We do not have a basis for distinguishing between the dispuited alternatives in collecting tubules and recognize that the process involved might be either hydrogen ion secretion or direct bicarboniate absorption.…”

Section: Resultsmentioning

confidence: 99%

Bicarbonate Secretion by Rabbit Cortical Collecting Tubules in Vitro

McKinney¹,

Burg²

1978

J. Clin. Invest.

106

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A B S T R A C T We previously reported that rabbit renal cortical collecting tubules can secrete bicarbonate in vitro (i.e., there can be net transport from bath to lumen, causing the concentration in the lumen to increase). Net bicarbonate secretion was observed most often when rabbits had been pretreated with NaHCO3 and were excreting alkaline urine before being killed for experiments. The purpose of the present studies was to elucidate the mechanism involved by testing the effects of ion substitutions and drugs on collecting tubules that were secreting bicarbonate. Acetazolamide inhibited net bicarbonate secretion, suggesting that the process is dependent upon carbonic anhydrase. Net bicarbonate secretion also decreased when sodium in the perfusate and bath was replaced by choline, but not when chloride was replaced by nitrate or methylsulfate. Ouabain had no significant effect. Amiloride caused net bicarbonate secretion to increase. The rate of net secretion did not correlate with transepithelial voltage. The results are compared to those in turtle urinary bladders that also secrete bicarbonate. There are no direct contradictions between the results in the two tissues, i.e., in turtle bladders acetazolamide also inhibited bicarbonate secretion and ouabain had no effect. Nevertheless, it seems unlikely that net secretion of bicarbonate by collecting tubules involves specific exchange for chloride, as has been proposed for turtle bladders, because replacement of chloride by other anions did not inhibit bicarbonate secretion by collecting tubules. It was previously shown that the collecting tubules in vitro also may absorb bicarbonate, especially when the rabbits have been treated with NH4C1 and are excreting acid urine before being killed.

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Section: Resultsmentioning

confidence: 99%

Bicarbonate Secretion by Rabbit Cortical Collecting Tubules in Vitro

McKinney¹,

Burg²

1978

J. Clin. Invest.

106

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“…(a) hydrogen secretion into bicarbonate-containing tubular fluid, thereby generating carbonic acid (1-6), (b) direct bicarbonate reabsorption (7), or (c) a combination of both mechanisms (8).…”

Section: Introductionmentioning

confidence: 99%

Direct determination of PCO2 in the rat renal cortex.

DuBose¹,

Pucacco²,

Seldin³

et al. 1978

J. Clin. Invest.

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“…However, as long as the cellular pCO 2 and, consequently, the cell-to-lumen gradient of pCO~ remain unknown, one cannot conclude that proton secretion is the only direct cause of any observed increase in the mucosal-to-serosal gradient pCO 2 (cf., Fig. 4 of Brodsky and Schilb, 1974).…”

Section: Can Both the C02-decreasing And C02-increasing Processes Of mentioning

confidence: 99%

“…The observed excess of excreted titratable acid over concomitantly filtered CO~ + H~CO s in phosphateloaded dogs (Pitts and Alexander, 1945) cannot exclude a bicarbonate-reabsorbing mechanism of urinary acid excretion unless one assumes that the apical membranes of the renal tubular cells block the cell-to-lumen diffusion but not the lumen-to-cell diffusion of CO 2 (Brodsky and Schilb, 1974). The CO2-increasing pattern of luminal acidification in turtle bladder sacs under conditions imposed by Schwartz et al (1974) can also be ascribed to bicarbonate reabsorption as well as proton secretion.…”

Section: Bicarbonate Reabsorption: a Frequently Rejected Hypothesismentioning

confidence: 99%

“…In principle, a time-dependent decrease or increase in the luminal concentration of dissolved CO~ ([CO~]e) should be the most critical parameter for determining whether bicarbonate reahsorption or proton secretion is the mechanism responsible for the observed acidification of (HCOs + CO~)-containing luminal fluids in isolated turtle bladder sacs (Brodsky and Schilb, 1974). This claim would be undeniable, if one were able to estimate and correct for any concomitant diffusion of CO 2 from nonacidifying and acidifying cells into the enclosed luminal fluid or from the enclosed luminal fluid into these cells.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

In vivo environmental temperature and the in vitro pattern of luminal acidification in turtle bladders. Evidence for HCO3 ion reabsorption.

Schilb

Durham

Brodsky

1988

The Journal of General Physiology

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In this study, it is shown how to transfer tared aliquots of (HCO 3 + CO2)-containing luminal fluids directly into the mercury-sealed chamber of a modified Van Slyke apparatus and how to obtain direct as well as indirect manometric determinations of dissolved CO~ ( turtles; and (c) a CO~-increasing pattern of luminal acidification is found in most of the bladders from 21~ -adapted turtles. A postulated bicarbonate ion-reabsorbing pump is consistent with all of these patterns of luminal acidification.

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The Means of Distinguishing between Hydrogen Secretion and Bicarbonate Reabsorption: Theory and Applications to the Reptilian Bladder and Mammalian Kidney

Cited by 20 publications

References 59 publications

Bicarbonate Secretion by Rabbit Cortical Collecting Tubules in Vitro

Bicarbonate Secretion by Rabbit Cortical Collecting Tubules in Vitro

Direct determination of PCO2 in the rat renal cortex.

In vivo environmental temperature and the in vitro pattern of luminal acidification in turtle bladders. Evidence for HCO3 ion reabsorption.

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