Renal acid excretion in early infancy

Manz, Friedrich; Kalhoff, Hermann; Remer, Thomas

doi:10.1007/s004670050270

Cited by 46 publications

(47 citation statements)

References 53 publications

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“…There was a striking increase in the number of pendrin-positive and pendrin-negative IC in both the CNT and the CD during the first 3 wk after birth. The increase in pendrin expression parallels the acquisi- BASIC RESEARCH www.jasn.org tion of bicarbonate secretion in the CCD, 6 a process that is thought to involve pendrin. 18 It is interesting that there were no BrdU-labeled nuclei in the pendrin-positive cells, and only a few BrdU-labeled nuclei were observed in pendrin-negative type A IC.…”

Section: Discussionmentioning

confidence: 77%

Origin and Fate of Pendrin-Positive Intercalated Cells in Developing Mouse Kidney

Song

Kim

Lee

et al. 2007

Journal of the American Society of Nephrology

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Pendrin is an apical anion exchanger found in type B and nonA-nonB intercalated cells that is involved in bicarbonate secretion. The purpose of this study was to establish the origin and fate of pendrinpositive intercalated cells in the mouse kidney. Using immunohistochemistry, we found that pendrinpositive cells first appeared in the connecting tubule at embryonic day 14 (E14) and subsequently in the medullary collecting duct at E18. Most of the pendrin-positive cells in the connecting tubule were nonA-nonB intercalated cells, wheras those in the medullary collecting duct were type B intercalated cells. In the cortical collecting duct, pendrin-positive cells appeared in the inner part at day 4 after birth and in the outer part at day 7. Pendrin-positive cells gradually disappeared by apoptosis from the inner part of the medullary collecting duct two weeks after birth. Using 5-bromo-2Јdeoxy-uridine (BrdU) to follow cell proliferation, we determined that selective proliferation of pendrin-positive intercalated cells does not occur; instead, these cells may arise from undifferentiated precursor cells from separate foci, one in the connecting tubule and one in the collecting duct.

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Section: Discussionmentioning

confidence: 77%

Origin and Fate of Pendrin-Positive Intercalated Cells in Developing Mouse Kidney

Song

Kim

Lee

et al. 2007

Journal of the American Society of Nephrology

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“…In human newborns, small infants and in animal models (with the exception of rabbits) it was noted that plasma HCO 3 − levels and the renal threshold for HCO 3 − are lower [11,38] and that the renal capacity to excrete protons and acid-equivalents is only acquired at a later stage of development [6,7,28]. Accordingly, analysis of transport processes in whole organisms as well as in isolated brush border membranes or proximal tubules showed increases in activity of NHE3 [4,5,7], paralleled by increases in protein abundance [4].…”

Section: Discussionmentioning

confidence: 99%

“…After birth the kidney is not completely matured and excretory and reabsorptive functions are not fully developed as evident from animal models as well as from clinical measurements in newborns and infants [6,10,11,28,51]. In human newborns, small infants and in animal models (with the exception of rabbits) it was noted that plasma HCO 3 − levels and the renal threshold for HCO 3 − are lower [11,38] and that the renal capacity to excrete protons and acid-equivalents is only acquired at a later stage of development [6,7,28].…”

Section: Discussionmentioning

confidence: 99%

Postnatal expression of transport proteins involved in acid?base transport in mouse kidney

Bonnici

Wagner

2004

Pfl�gers Archiv European Journal of Physiology

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The kidney plays a major role in maintaining and controlling systemic acid-base homeostasis by reabsorbing bicarbonate and secreting protons and acidequivalents, respectively. During postnatal kidney development and adaptation to changing diets, plasma bicarbonate levels are increasing, the capacity for urinary acidification maturates, and the final morphology and distribution of intercalated cells is achieved. In adult kidney, at least two types of intercalated cells (IC) are found along the collecting duct characterised either by the expression of AE1 (type A IC) or pendrin (non-type A IC) where non-type A IC are found only in the convoluted distal tubule, connecting tubule and cortical collecting duct. Here we investigated in mouse kidney the relative mRNA abundance, protein expression levels and distribution of several proteins involved in renal acid-base transport, namely, the Na + /HCO 3 − cotransporter NBC1 (SLC4A4), the Na + /H + -exchanger NHE3 (SLC9A3), two subunits of the vacuolar H + -ATPase [ATP6V0A4 (a4), ATP6V1B1 (B1)], the Cl − /HCO 3 − exchangers AE1 (SLC4A1) and pendrin (SLC26A4). Relative mRNA abundance of all transport proteins was lowest at day 3 after birth and increased thereafter in parallel with protein levels. The numbers of type A and non-type A IC in the cortical collecting duct (CCD) increased from day 3 to days 18 and 24, whereas the number of IC in the CCD with apical staining for the vacuolar H + -ATPase subunits a4 and B1 decreased from day 3 to days 18 and 24, respectively. In addition, cells with characteristics of nontype A IC (pendrin expression, basolateral expression of vacuolar H + -ATPase subunits) were found in the inner and outer medulla 3 days after birth but were absent from the medulla of 24-day-old mice. Taken together, these results demonstrate massive changes in mRNA and protein expression levels of several acid-base transporters during postnatal kidney maturation and also show changes in intercalated cell phenotype in the medulla during these processes.

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“…In small preterm babies, renal acid excretion capacity is low compared to term newborns [1]. However, nutrition with standard formulas already may result in an actual renal acid excretion (NAE) in the range of maximum renal acid excretion.…”

Section: Introductionmentioning

confidence: 99%

Food Composition and Acid-Base Balance: Alimentary Acid Load and Clinical Implications in Neonates

Kalhoff¹,

Manz²,

Kiwull³

et al. 2008

TONUTRJ

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Abstract:In preterm neonates, functional limits of pulmonary and/or renal regulation processes and the considerable acid load of common formulas predispose to a great risk for the development of latent metabolic acidosis, characterized by e.g. impaired mineralization and reduced growth. Furthermore, in a prospective study in very low birth weight-infants, latent metabolic acidosis was assumed to contribute to the development of nephrocalcinosis. To obtain fundamental data of acidbase regulation in preterm infants under different diets, we investigated 48 preterm infants fed their own mother`s milk (28 native human milk, 20 enriched with fortifier) and 34 patients on formula (23 on a standard batch, 11 on a modified batch with reduced acid load). Irrespective of the diet, we could not find notable differences between individual data of acid-base status in blood samples. In contrast, dietary acid-base intake was accurately reflected in the urine, pointing to effective individual compensation of alimentary acid-load by renal base saving mechanisms. Thus, in preterm infants, nutritional acid-base challenges can be judged earlier and more safely by urinary than by blood acid-base analysis A physiologically based and empirically adjusted calculation model allows to estimate the impact of mineral and protein content of a formula on the urinary ionogram and thus on the average renal net acid excretion in a regularly fed and growing preterm infant. The algorithm of this proposed calculation model could prove to be a useful tool in the design of new formulas with adaequate base supply for preterm infants.

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Renal acid excretion in early infancy

Cited by 46 publications

References 53 publications

Origin and Fate of Pendrin-Positive Intercalated Cells in Developing Mouse Kidney

Origin and Fate of Pendrin-Positive Intercalated Cells in Developing Mouse Kidney

Postnatal expression of transport proteins involved in acid?base transport in mouse kidney

Food Composition and Acid-Base Balance: Alimentary Acid Load and Clinical Implications in Neonates

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