An In Vitro Demonstration of Increased Collecting Tubular Permeability to Urea in the Presence of Vasopressin*

Gardner, Kenneth D.; Maffly, Roy H.

doi:10.1172/jci105070

Cited by 14 publications

(7 citation statements)

References 22 publications

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“…Such an action of A.D.H. on permeability to urea has been suggested previously for the collecting duct of the dog (Jaenike, 1961;Aukland, 1961), rat (Gardner & Maffly, 1964), man (Thomas, 1964) and rabbit (Foulkes, 1966) although not confirmed in the rabbit collecting duct (Grantham & Burg, 1966).…”

Section: Discussionmentioning

confidence: 59%

The time course of changes in renal tissue composition during water diuresis in the rat

Atherton¹,

Hai²,

Thomas³

1968

The Journal of Physiology

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SUMMARY1. The time course and extent of changes in the composition of renal tissue slices in water diuresis were determined by sacrificing groups of rats before and during the intravenous infusion of dextrose (2.5 g/100 ml.) in amounts sufficient to administer over 2 hr, and subsequently to maintain for up to 74 hr, a positive fluid load of 4 % body weight.2. The corticomedullary osmolal gradient characteristic of the nondiuretic rats was progressively dissipated until, at 74 hr, only papillary tip concentrations were higher than those of other segments.3. The changes in individual constituents followed different time courses: (i) an increase in water content in all segments, particularly the papilla, was almost complete by 1 hr, preceding the maximal increases in urine flow; (ii) a marked decrease in papillary and medullary urea content in the first hour was followed by a slower, progressive decrease leading to an almost complete dissipation of the urea gradient by 74 hr; (iii) small, non-significant decreases in sodium content occurred in all segments in the first hr, followed by a further small, progressive decrease in papillary sodium content; (iv) changes in ammonium and potassium concentrations were mainly related to those in water content, since the contents of these solutes showed only small changes.4. By 2 hr, differences in the rates of decline of osmolal and urea concentrations in urine and papilla led to urinary concentrations significantly lower than papillary values. The steep papilla-urine urea concentration difference became smaller, but remained significant even at 74 hr.5. The findings are discussed in terms of changes in countercurrent mechanisms, particularly as influenced by anti-diuretic hormone.6. The development of papilla/urine urea concentration ratio greater than unity is also considered in terms of passive transport with changes in membrane permeability.

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Section: Discussionmentioning

confidence: 59%

The time course of changes in renal tissue composition during water diuresis in the rat

Atherton¹,

Hai²,

Thomas³

1968

The Journal of Physiology

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“…An effect of A.D.H. on collecting duct permeability to urea has been suggested previously in the dog (Jaenike, 1961;Aukland, 1961), rat (Gardner & Maffly, 1964), man (Thomas, 1964) and rabbit (Foulkes, 1966) but was not confirmed in the rabbit collecting duct (Grantham & Burg, 1966). If such A.D.H.…”

Section: Discussionmentioning

confidence: 84%

The time course of changes in renal tissue composition during mannitol diuresis in the rat

Atherton¹,

Hai²,

Thomas³

1968

The Journal of Physiology

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SUMMARY1. The time course and extent of changes in the composition of renal tissue slices in osmotic diuresis were determined by sacrificing groups of rats before and during the intravenous infusion of mannitol (15 g/100 ml.) for up to 71 hr.2. Very rapid changes in tissue water and solute contents occurred within 15 min, preceding the times of maximal diuresis, with little subsequent change even up to 7-hr.3. The main changes were: (a) an increase in water content in all slices, particularly the papilla; (b) a very profound decrease in papillary and medullary urea content in the first 15 min, with a small, but significant, further decrease, subsequently; (c) a small, but significant, rapid decrease in papillary sodium, and small non-significant increases in the outer medulla and cortex. Subsequent changes in any segment were small and non-significant; (d) apart from small changes in the first 15 min ammonium and potassium contents remained fairly constant.4. The rates of change in papillary and urinary urea concentrations were similar, so that after 30 min, any differences between tip and urinary concentrations were small and non-significant.5. The findings are discussed in terms of factors influencing countercurrent mechanisms. It is concluded that altered medullary blood flow is mainly responsible for the rapid changes in medullary composition.6. The relation between papillary and urinary urea concentrations is explicable in terms of passive handling, with equilibration across a freely permeable collecting duct membrane.

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“…Rather, vasopressin, which alters water permeability of the distal nephron, might indirectly influence urea transport by changing intratubular urea concentration. Although vasopressin increases the permeability of the toad bladder to both water and urea (7) and in vitro perfusion studies of rat collecting duct have been interpreted as suggesting similar effects (34), recent direct observations indicate that vasopressin acts on the distal tubule of the rat (35) and the collecting tubule of the rabbit (8) to change their permeability to water and not to urea. These latter findings are perfectly compatible with our hypothesis outlined above.…”

Section: Methodsmentioning

confidence: 99%

Uphill Transport of Urea in the Dog Kidney: Effects of Certain Inhibitors*

Goldberg¹,

Wojtczak²,

Ramirez³

1967

J. Clin. Invest.

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Summary. To study the renal medullary transport and accumulation of urea in dogs independent of water transport, we obliterated the medullary electrolyte gradient by a sustained ethacrynic acid diuresis. Infusions of urea were also given at various rates to vary urinary urea concentration. In the steady state, the kidneys were removed, and slices were analyzed for water, urea, and electrolytes. In every experiment in 15 dogs over a range of urinary urea concentration from 19 to 230 mmoles per L and urine flow from 0.5 to 9.7 ml per minute per kidney, an intrarenal urea gradient persisted, and urinary urea concentration was always lower than papillary water urea concentration. The magnitude of this uphill urinary-papillary gradient (mean + SE = -21 + 2.9 mmoles per L) was not affected by hemorrhagic hypotension or a nonprotein diet.In 12 additional experiments begun similarly, inhibitors were infused into one renal artery. Both iodoacetate, an inhibitor of anaerobic glycolysis, and acetamide, an analogue of urea, markedly and significantly reduced both the intrarenal urea gradient and the uphill urinary-papillary gradient. In contrast, cyanide, an inhibitor of oxidative metabolism, had no observable effect on the urea gradients. The data are best explained by postulating an active transport system for urea in the medullary collecting duct deriving its energy from anaerobic glycolysis.

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An In Vitro Demonstration of Increased Collecting Tubular Permeability to Urea in the Presence of Vasopressin*

Cited by 14 publications

References 22 publications

The time course of changes in renal tissue composition during water diuresis in the rat

The time course of changes in renal tissue composition during water diuresis in the rat

The time course of changes in renal tissue composition during mannitol diuresis in the rat

Uphill Transport of Urea in the Dog Kidney: Effects of Certain Inhibitors*

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