Reduced sodium reabsorption by the proximal tubule of Doca-escaped dogs

Wright, Fay; Knox, FG; Ss, Howards; Berliner, Robert W.

doi:10.1152/ajplegacy.1969.216.4.869

Cited by 44 publications

(18 citation statements)

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“…Although absolute fluid reabsorption in proximal tubule is increased proportionately, indicating the operation of glomerulo-tubular balance, end-proximal delivery in the high-salt group remains elevated. This latter finding is in agreement with results obtained in DOCA-escaped dogs (4,12). The difference in tubular load persists to the beginning of the distal tubule, despite increased sodium transport in loop of Henle of DOCA-treated rats, calculated as the difference in load between end of proximal and beginning of distal tubule.…”

Section: Discussionsupporting

confidence: 92%

“…One possibility is development of insensitivity to mineralocorticoids, presumably in distal tubule; another is an increase in circulating levels of an unknown natriuretic substance (3). In dogs, a reduction of proximal tubular reabsorption has been observed Received for publication 13 March 1972 and in revised form 17 October 1972. (luring deoxycorticosterone acetate (DOCA) 1-escape (4), and suggested as a cause for the rise in sodium excretion. Since fractional transport in proximal tubule mav be inhibited with little change in natriuresis (5) absolute as well as fractional reabsorptions were studied in proximal and distal tubules of rats showing enhanced urinary sodium excretion despite continued steroid administration.…”

Section: Introductionmentioning

confidence: 99%

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Proximal and Distal Tubular Function in Salt-Deprived and in Salt-Loaded Deoxycorticosterone Acetate-Escaped Rats

Sonnenberg¹

1973

J. Clin. Invest.

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A B S T R A C T Proximal and distal tubular function was compared with urinary excretion in rats after chronic administration of salt and deoxycorticosterone acetate (DOCA) or during salt deprivation. DOCA rats excreted significantly more sodium than did salt-deprived rats. Measurements of tubular fluid to plasma (TF/P) inulin ratios and concentrations of sodium and potassium in quantitative, timed collections, related to measured tubular length, allowed calculation of absolute reabsorption of fluid and ions in the different nephron segments. Proximal transport was not reduced in DOCAtreated rats compared with salt-deprived animals; in distal tubule the former group reabsorbed more sodium and secreted less potassium than the latter. Calculation of sodium transport in loop of Henle as the difference in flow between the end of the proximal convolution and the beginnings of the distal tubule indicated no inhibition of reabsorption in DOCA animals. Comparison of end-distal tubular flow with simultaneous urinary excretion suggested that sodium load was not the determining factor of enhanced natriuresis in DOCAtreated animals. The data are interpreted as indicating that DOCA-escape in the rat is associated with specific alteration of sodium transport in the collecting duct system.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Proximal and Distal Tubular Function in Salt-Deprived and in Salt-Loaded Deoxycorticosterone Acetate-Escaped Rats

Sonnenberg¹

1973

J. Clin. Invest.

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“…Thus, a natriuretic hormone may not be necessary to account for the diuresis of acute saline loading. However, the depression of tubular sodium reabsorption, demonstrated during deoxycorticosterone (DOCA) escape (29) and hyperoncotic albumin infusion (30,31), does not appear to be associated with Sodium Transport Inhibitor in Plasma of Saline-Loaded Dogs the same dilutional and hemodynamic changes which accompany massive saline infusions. Additional studies will be necessary to determine whether the factor demionstrated in our studies plays a role in either of these situations or in any of the other as yet unexplained natriuretic states.…”

Section: Methodsmentioning

confidence: 99%

The effect of dialysates and ultrafiltrates of plasma of saline-loaded dogs on toad bladder sodium transport

Buckalew¹,

Martínez²,

Green³

1970

J. Clin. Invest.

108

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A B S T R A C T In order to obtain direct evidence for the existence of a natriuretic hormone, dialysates and ultrafiltrates of plasma of dogs expanded with saline were tested for effects on sodium transport by the toad urinary bladder. Dialysate was obtained by dialysis of blood in vivo in a clinical dialyzer and by dialysis in vitro of small volumes of blood using a miniature model of the clinical dialyzer. Ultrafiltrates were prepared using selective molecular filters which permit passage of substances on the basis of molecular weight and three dimensional configuration.Dialysates and ultrafiltrates of hydropenic dogs caused a change in toad bladder potential difference of + 1% and in short circuit current of -5%. In contrast, dialysates and ultrafiltrates from expanded dogs caused a change in potential difference of -23% and in short circuit current of -32%, a highly significant difference. Onset of reduction of short circuit current occurred within 3-5 min, reaching a maximum in 10-20 min. The effect was rapidly reversible, was specific for the serosal surface of the bladder, and could not be explained on the basis of nonspecific alterations in ionic composition or by dilutional effects. Ultrafiltrates of jugular vein plasma caused significantly more reduction of short circuit current than ultrafiltrates of femoral vein plasma. The data indicate the presence in plasma of saline-loaded dogs of a dialyzable inhibitor of toad bladder sodium transport. Ultrafiltrate studies using membranes of appropriate selectivity suggest the factor has a molecular weight of less than 3000.

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“…Several early reports Wiederholt, Stolte, Brecht & Hierholzer, 1966;Stumpe & Ochwaldt, 1968;Stolte, Wiederholt, Fuchs & Hierholzer, 1969) on the rat concluded that mineralocorticoids enhanced proximal tubule reabsorption after observation of reduced reabsorption in adrenalectomized or salt-loaded rats which was restored with aldosterone, but not dexamethasone, therapy. However, as a result of other studies on the rat (Cortney, 1969;Martin & Berliner, 1969), dog (Wright, Knox, Howards & Berliner, 1969;Lynch, Schneider, Willis & Knox, 1972) and rabbit , which found no evidence of direct mineralocorticoid stimulation of reabsorption, it is accepted by most reviewers (Sharp & Leaf, 1973;Burg, 1976;Bonvalet, 1987) that proximal tubule reabsorption is independent of mineralocorticoid control. It has been suggested (Lynch et al 1972;Sharp & Leaf, 1973;Burg, 1976; that the apparent stimulation of proximal tubule reabsorption by aldosterone indicated by some studies is due to indirect systemic effects, including changes in extracellular volume and glomerular filtration rate, and potassium depletion, which result from perturbation of mineralocorticoid status.…”

Section: Concentration Of Electrolytes and Osmotic Pressure Of Blood mentioning

confidence: 99%

Adrenal independence of fluid and electrolyte reabsorption in the ductuli efferentes testis of the rat

Clulow²,

La³

et al. 1997

Experimental Physiology

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SUMMARYThe ductuli efferentes testis (efferent ducts) of the rat were studied to determine whether fluid and electrolyte reabsorption by the ducts is under the control of adrenal mineralocorticoids. Testicular fluid output and the rate of fluid reabsorption by the ducts were determined in sham-operated controls and in rats which had been adrenalectomized 10 days previously, adrenalectomized 10 days previously and given aldosterone therapy (75 jug kg-' day-' s.c.) from day 3 to day 10 post adrenalectomy, and in rats given injections of the aldosterone antagonist, spironolactone, for 10 days (10 mg kg-' day-' s.c.). The values for testicular fluid output and fluid flow from the efferent ducts (means + S.E.M.) in the sham-operated rats were 36 0 + 7-8 and 1-23 + 0-12 Jul h-', respectively, resulting in an estimate of fluid reabsorption by the efferent ducts of 94.8 + 1 6 % of the testicular fluid output. None of the treatments resulted in a significant change in testicular fluid output or in fluid reabsorption from the efferent ducts. Similarly, the treatments did not significantly alter the osmolality or electrolyte concentrations in fluid samples from the rete testis or the distal end of the efferent ducts (sham-operated values for rete testis and efferent duct fluid, respectively, were: osmolality, 311.2 + 1 7 and 302-7 + 5-7 mosmol kg-'; [Na+], 151-2 + 5-6 and 150 8 + 8-1 mmol 1'; [ClF], 147-9 + 6-6 and 126-7 + 2-2 mmol 1-'; [K+], 15 2 + 0 7 and 13-5 + 2 4 mmol 1-'). It is concluded that, like the homologous proximal tubule of the metanephric kidney, fluid reabsorption from the efferent ducts is independent of adrenal mineralocorticoid control.

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Reduced sodium reabsorption by the proximal tubule of Doca-escaped dogs

Cited by 44 publications

References 0 publications

Proximal and Distal Tubular Function in Salt-Deprived and in Salt-Loaded Deoxycorticosterone Acetate-Escaped Rats

Proximal and Distal Tubular Function in Salt-Deprived and in Salt-Loaded Deoxycorticosterone Acetate-Escaped Rats

The effect of dialysates and ultrafiltrates of plasma of saline-loaded dogs on toad bladder sodium transport

Adrenal independence of fluid and electrolyte reabsorption in the ductuli efferentes testis of the rat

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