The Role of Potassium in Active Transport of Sodium by the Toad Bladder

Essig, Alvin; Leaf, Alexander

doi:10.1085/jgp.46.3.505

Cited by 105 publications

(56 citation statements)

References 4 publications

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“…One may, in fact, calculate from their data that the pool contained some 52% of total tissue sodium. Under the circumstances of their experiments, total sodium falls by about 80% (Essig and Leaf, 1963). Since the bulk of the remaining sodium in these experiments must have been in the epithelial cells, this calculated fraction is quite similar to that observed here.…”

Section: Discussionsupporting

confidence: 78%

The Kinetics of Sodium Transport in the Toad Bladder

Finn

Rockoff

1971

The Journal of General Physiology

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A compartmental model of toad bladder sodium content has been developed, whereby it is possible to measure the four unidirectional fluxes across the opposite faces of the transport compartment, as well as the amount of sodium in the compartment. 24Na is added to the mucosal medium of a short-circuited bladder mounted between halves of a chamber in which the fluid is stirred by rotating impellers. After a steady state is reached, nonradioactive medium is flushed through both sides of the chamber, collected, and counted. The data from each chamber are fitted to sums of exponentials and interpreted in terms of conventional compartmental analysis. Three exponentials are required, with half-times of 0.2, 2.2, and 14.0 min. It is shown that the first of these represents chamber washout, the second the transport pool, and the third a tissue compartment which is not involved in active sodium transport and which does not communicate with the transport pool. The second compartment contains 10.5 #&Eq of sodium per 100 mg dry weight, an amount equal to approximately 30 % of total tissue sodium. The results also indicate, as expected from electrophysiological data, that the mucosal-facing side of the transport compartment is over 10 times as permeable to sodium as the serosal, or pump, side.The isolated urinary bladder of the toad, like other oriented multicellular membranes, carries out the net transport of sodium against an electrochemical potential gradient. It has been assumed that sodium must cross at least two barriers in order to traverse the bladder, one at the mucosal, the other at the serosal, boundary of the cells. In actual fact, satisfactory evidence for the presence of such a simple model has been difficult to obtain. Furthermore, there are at least four cell types which make up the epithelial layer of the bladder (Choi, 1963;Peachey and Rasmussen, 1961). Quantitative considerations make it likely that the most numerous of these, the granular layer, carries

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Section: Discussionsupporting

confidence: 78%

The Kinetics of Sodium Transport in the Toad Bladder

Finn

Rockoff

1971

The Journal of General Physiology

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“…In the experiments in Fig. 5, the bladders initially manifested a higher Pure& than reported elsewhere (13) depleted (18)(19)(20) hr)/(0-2 hr) for Purs. = 3.47 (n = 9, P < 0.01).…”

Section: Resultsmentioning

confidence: 49%

“…There is also evidence of "ion binding" by the tissue since the concentration of tissue electrolytes exceeds the concentration in the Ringer's solution (5,18,19, and Table I, Timeo). Thus, although there are no significant changes in Table I or in the study by Crabbe (5), it is still conceivable that aldosterone causes a critical but thus far undetected change in the electrolyte composition of certain epithelial cells in the bladder.…”

Section: Resultsmentioning

confidence: 99%

Effect of Adrenal steroid hormones on the response of the toad's urinary bladder to vasopressin

Handler¹,

Preston²,

Orloff³

1969

J. Clin. Invest.

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A B S T R A C T This study was designed to examine the effect of adrenal steroid hormones on the response of the toad bladder to vasopressin. Aldosterone enhanced the short-circuit current response, the osmotic water flow response, and the urea permeability response to vasopressin. Since aldosterone also enhanced the short-circuit current response and the osmotic water flow response to adenosine 3',5'-monophosphate, the steroid effect on the bladder's response to vasopressin appears to be at a step beyond the stimulation of adenyl cyclase.Indirect evidence was obtained that the effect of adrenal steroid hormones on the osmotic water flow response to vasopressin is mediated by a different hormone-tissue interaction than that mediating the effect of adrenal steroid hormones on sodium transport. In experiments with three different pairs of mineralocorticoid and glucocorticoid analogues, the former had a greater effect on short-circuit current, the latter on the osmotic water flow response to vasopressin. In addition, the spirolactone SC-14266 markedly inhibited the short-circuit current effect of dexamethasone and had little or no inhibitory effect on the dexamethasone enhancement of the osmotic water flow response to vasopressin. Aldosterone and dexamethasone stimulate the oxidation by the bladder of glucose-6-14C and depress the rate of oxidation of glucose-1-'4C compared with glucose-6-"C. SC-14266 inhibited the effect of dexamethasone on the oxidation of glucose-6-"C but did not alter the effect of the steroid on the rate of oxidation of glucose-1-14C compared with glucose-6-Y4C, suggesting that the latter is a glucocorticoid effect and the stimulation of glucoseThis work was published in part in abstract: Handler,

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“…As stated above, these studies only establish the active nature of the two processes; they do not distinguish between any of the current models which have been postulated to account for transport in epithelial or other cells. K+ secretion and Na' reabsorption are interdependent in this tissue as in others (18). Thus net secretion of K+ decreases when the Na' concentration of luminal fluid is lowered; Nat reabsorption falls when K' is eliminated from the bathing medium.…”

Section: Discussionmentioning

confidence: 60%

The nature of transtubular Na and K transport in isolated rabbit renal collecting tubules

Burg¹,

Orloff²

1970

J. Clin. Invest.

205

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A B S T R A C T In order to investigate the mechanism of Na and K transport, rabbit cortical collecting tubules were perfused in vitro and the concentrations of Na and K in lumen and bathing fluid and the transtubular electrical potential difference (PD) were measured.When the perfusate and external bath contained 150 Na-5 K (mEq liter'), the sodium concentration decreased and the potassium concentration increased by an approximately equal amount in collected tubular fluid. The transtubular electrical potential was equal at both ends of the tubule in the steady state and ranged between 21 and 67 mv, lumen negative. In all tubules perfused at rates less than 0.5 nl min', the K concentration of the collected fluid was higher and the Na concentration lower than that predicted for electrochemical equilibrium between lumen fluid and external bath, evidence for active transtubular transport of both cations. These results differ from those observed in rat distal tubule in which potassium secretion is passive.Active Na and K transport and the transtubular PD were decreased by (a) ouabain, (b) removal of sodium from the perfusate, or (c) removal of potassium from the external bath, evidence of interdependence of Na and K transport. The dependence of active K secretion on intraluminal Na concentration accounts for the phenomenon of "distal" Na-K exchange noted previously in clearance and stop-flow studies. The mechanism of Na transport may in part be electrogenic since the rate of decline of the transtubular PD in low K media was faster than could be accounted for on the basis of a reduction in cell potassium concentration.

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The Role of Potassium in Active Transport of Sodium by the Toad Bladder

Cited by 105 publications

References 4 publications

The Kinetics of Sodium Transport in the Toad Bladder

The Kinetics of Sodium Transport in the Toad Bladder

Effect of Adrenal steroid hormones on the response of the toad's urinary bladder to vasopressin

The nature of transtubular Na and K transport in isolated rabbit renal collecting tubules

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