Independence of Hydrogen Ion Secretion and Transport of Other Electrolytes in Turtle Bladder*

Steinmetz, Philip R.; Omachi, Rodney S.; Frazier, Howard S.

doi:10.1172/jci105645

Cited by 70 publications

(19 citation statements)

References 12 publications

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“…These results include values obtained with the mucosal pH being varied from 5 to 7.4. The equivalence of those two methods of measurements confirms the earlier findings of Steinmetz (30).…”

Section: Measurement Of the Rate Of H + Secretionsupporting

confidence: 88%

Active H+ transport in the turtle urinary bladder. Coupling of transport to glucose oxidation.

Beauwens¹,

Al‐Awqati²

1976

The Journal of General Physiology

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The turtle urinary bladder acidifies the contents of its lumen by actively transporting protons. H + secretion by the isolated bladder was measured simultaneously with the rate of '4CO2 evolution from ['4C]glucose.The application of an adverse pH gradient resulted in a decline in the rate of H + secretion (Jn) and in the rate of glucose oxidation (J~o~). The changes in J. and J~o, were linear functions of the pH difference across the membrane. Hence, JN and J~o~ were linearly related to each other. The slope, OJn/OJ~o2 was found to be similar in half-bladders from the same animal but was seen to vary widely in a population of turtles.To investigate the effect of pH gradients on OJH/OJ~o,, two experiments were performed in each of 14 hemibladders. In one,JH andJ~o2 were altered by changing the luminal pH. In the other, they were altered by changing the ambient pCO2 while the luminal pH was kept constant. The average slope, oJa/OJ~o2, in the presence of pH gradients was 14.45 eq-tool -~. In the absence of gradients in the same hemibladders it was 14.72, A = 0.27 -+ 1.46.The results show that H + transport is organized in such a way that leaks to protons in parallel to the pump are negligible. Analysis of the transport system by use of the Essig-Caplan linear irreversible thermodynamic formalism shows that the system is tightly coupled. The degree of coupling, q, given by that analysis was measured and found to be at or very near the maximum theoretical value.

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“…These results include values obtained with the mucosal pH being varied from 5 to 7.4. The equivalence of those two methods of measurements confirms the earlier findings of Steinmetz (30).…”

Section: Measurement Of the Rate Of H + Secretionsupporting

confidence: 88%

Active H+ transport in the turtle urinary bladder. Coupling of transport to glucose oxidation.

Beauwens¹,

Al‐Awqati²

1976

The Journal of General Physiology

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“…H' secretion and Na+ absorption, on the other hand, can be supported to an appreciable extent by anaerobic energy. Thus, Steinmetz, Omachi, and Frazier (9) observed that dinitrophenol failed to inhibit H+ secretion in their system in which exogenous C02 was absent. Similarly H' secretion was reduced only moderately' by deoxygenation carried out at a constant CO.…”

Section: Discussionmentioning

confidence: 94%

Energy dependence of urinary bicarbonate secretion in turtle bladder.

Oliver¹,

Himmelstein²,

Steinmetz³

1975

J. Clin. Invest.

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A B S T R A C T Addition of HCOi-to the serosal side (S) of the isolated turtle bladder results in a HCO0-flow from S to the mucosal side (M) which markedly reduces the net rate of acid secretion. To characterize the driving forces for this downhill HCO3-flow, the effects of metabolic inhibitors and substrates were examined. In short-circuited bladders with the M pH lowered to the point of zero net H+ secretion, the rate of HCO-entry into M in response to a 20-mM HCO3-gradient was measured by pH stat titration. Deoxygenation reduced the HC03-flux from 1.24±0.1 gM/h/8 cm2 (SEM) to 0.50±0.1 tM/h with glucose (2 X 10' M) and from 1.32±0.1 to 0.47±0.1 iAM/h without glucose.A similar reduction (61%) was observed in the presence of 1% C02. Dinitrophenol (10' M), cyanide (10' M), and deoxyglucose (10-' M) inhibited the HCO3-flux by 39%, 37%, and 38%, respectively. The combination of any of these inhibitors with N2 caused the same inhibition as Ns alone. In bladders depleted of substrate, pyruvate (5 X 10-' M) increased the HCOs-flux from 0.36 ±0.05 to 0.58±0.01 ,M/h (P < 0.005); the increment was abolished by deoxygenation.The results indicate that the bulk of the downhill HCOi-flow in this system is dependent on metabolic energy derived primarily from oxidative sources, and that this energy-dependent flow approximates the electroneutral component of HCO3-secretion that is coupled to Cl-absorption.

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“…Hence, it must be coupled either directly to metabolic energy production or to the active transport of another ion such as Na+ or Cl-, a possibility examined in the following article (9).…”

Section: Discussionmentioning

confidence: 99%

Characteristics of Hydrogen Ion Transport in Urinary Bladder of Water Turtle*

Steinmetz¹

1967

J. Clin. Invest.

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Abstract. The mechanism of acidification by the urinary bladder of the water turtle was studied in an in vitro system which permitted control and measurement of electrical and concentration driving forces. The rate of hydrogen ion secretion was measured by means of a pH stat technique in the absence of exogenous carbon dioxide and bicarbonate.Transport of hydrogen ion into the solution bathing the mucosal surface of the bladder was associated with the appearance of alkali in the serosal compartment. The mean rate of hydrogen ion secretion in the absence of electrical and concentration gradients across the bladder was 0.96 Mumole/hr. The secretion rate was only slightly greater in the presence of the spontaneous potential difference. The maximal hydrogen ion gradient that could be generated by the bladder was 3.33 pH units in the presence of the spontaneous voltage and 3.02 pH units in the short-circuited state.Hydrogen ion secretion was markedly reduced by acetazolamide and anaerobiosis, which indicated that under our experimental conditions acidification depended on the production and enzymatic hydration of metabolic carbon dioxide. On the basis of the stoichiometry of the pH changes across the membrane under different conditions, it is suggested that the active transport mechanism for hydrogen ion is located near the mucosal surface of the epithelial cell and that the alkali generated in back of the pump moves passively into the serosal fluid along an electrochemical gradient.Introduction a limiting factor in our understanding of hydroThe urinary bladder of the fresh water turtle

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Independence of Hydrogen Ion Secretion and Transport of Other Electrolytes in Turtle Bladder*

Cited by 70 publications

References 12 publications

Active H+ transport in the turtle urinary bladder. Coupling of transport to glucose oxidation.

Active H+ transport in the turtle urinary bladder. Coupling of transport to glucose oxidation.

Energy dependence of urinary bicarbonate secretion in turtle bladder.

Characteristics of Hydrogen Ion Transport in Urinary Bladder of Water Turtle*

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