Biochemical Characterization of Individual Nephron Segments

Guder, W. G.; Morel, François M. M.

doi:10.1002/cphy.cp080246

Cited by 6 publications

(11 citation statements)

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“…In contrast to succinate dehydrogenase studied in parallel (Figure 3 and 4), choline dehydrogenase activity was very low in mitochondria of thick ascending limb of Henle's loop in agreement with activities of the microdissection study. This result confirms that different enzyme patterns exist in mitochondria of rat nephron (Guder and Morel, 1992). In collecting duct cells choline dehydrogenase seems to be present in all cell types, independent of the density of mitochondria as measured by succinate dehydrogenase activity.…”

Section: Distribution Of Betaine Synthesis In Nephron Segmentssupporting

confidence: 82%

Determination of Choline Dehydrogenase Activity along the Rat Nephron

Miller¹,

Schmid²,

Chen³

et al. 1996

Biological Chemistry Hoppe-Seyler

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A radioenzymatic microassay was developed to quantitate choline dehydrogenase activity in single microdissected nephron segments. This enzyme is the rate limiting step in the biosynthesis of betaine, which serves as an intracellular osmoregulatory organic solute in mammalian kidney. The enzyme localized in renal mitochondrial inner membrane forms betaine aldehyde, which in the assay is converted to betaine by oxidative treatment. A histochemical procedure based on the formazan detection of tetranitroblue tetrazolium chloride was applied in parallel. The results show that activities in proximal convoluted and straight tubules are more than 5 times higher (21 to 25 pmol h-1 mm tubule-1) compared to distal nephron segments with no significant differences along the proximal tubule. Along the osmotic gradient from the outer medullary towards the papillary structures enzyme activities increased in ascending limbs of Henle's loop and collecting tubules. Collecting ducts showed two times higher activities than ascending loop segments when corrected for tubular cell volumes. The quantitative data were confirmed by the histochemical procedure. The results allow for the conclusion that betaine synthesis is sufficient to build up renal betaine, but cannot explain the distribution pattern of betaine along the corticopapillary axis. Additional mechanisms like intrarenal and tubular transport have to be postulated.

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Section: Distribution Of Betaine Synthesis In Nephron Segmentssupporting

confidence: 82%

Determination of Choline Dehydrogenase Activity along the Rat Nephron

Miller¹,

Schmid²,

Chen³

et al. 1996

Biological Chemistry Hoppe-Seyler

View full text Add to dashboard Cite

show abstract

“…However, they are unable to utilize succinate or malate (7). Because substrate oxidation along the nephron is dependent on the distribution of the respective enzymes (8), distal nephron portions predominantly will use glucose for maintenance of their cellular ATP whereas proximal nephron portions preferentially use glutamine. The mammalian kidney further shows a remarkable substrate specificity and selectively extracts these substrates from the blood supply in considerable amounts.…”

Section: Role Of Nephron Heterogeneity In Nephrotoxicitymentioning

confidence: 99%

“…Rather, distinct cell populations may be particularly susceptible to a specific class of chemicals and resistant to injury from another class of chemicals. Renal epithelial cells of the proximal nephron are target sites for many nephrotoxic chemicals because of a large number of transport systems (8) and because of the presence of xenobiotic metabolizing enzymes such as cytochrome P450, reduced nicotinamide adenine dinucleotide phosphate-cytochrome C reductase, glucuronyl transferase, sulfotransferases, glutathione S-transferases (induding cysteine conjugate 3-lyase), monooxygenases, and prostaglandin H synthase (8)(9)(10)(11). In addition, intracellular concentrations of reduced glutathione (GSH) and GSH-dependent enzymes are highest in this nephron segment (8).…”

Section: Role Of Nephron Heterogeneity In Nephrotoxicitymentioning

confidence: 99%

Nephrotoxicity testing in vitro--what we know and what we need to know.

Pfaller

Gstraunthaler

1998

Environ Health Perspect

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The kidney is affected by many chemicals. Some of the chemicals may even contribute to end-stage renal disease and thus contribute considerably to health care costs. Because of the large functional reserve of the kidney, which masks signs of dysfunction, early diagnosis of renal disease is often difficult. Although numerous studies aimed at understanding the mechanisms underlying chemicals and drugs that target various renal cell types have delivered enough understanding for a reasonable risk assessment, there is still an urgent need to better understand the mechanisms leading to renal cell injury and organ dysfunction. The increasing use of in vitro techniques using isolated renal cells, nephron fragments, or cell cultures derived from specific renal cell types has improved our insight into the molecular mechanisms involved in nephrotoxicity. A short overview is given on the various in vitro systems currently used to clarify mechanistic aspects leading to sublethal or lethal injury of the functionally most important nephron epithelial cells derived from various species. Whereas freshly isolated cells and nephron fragments appear to represent a sufficient basis to study acute effects (hours) of nephrotoxins, e.g., on cell metabolism, primary cultures of these cells are more appropriate to study long-term effects. In contrast to isolated cells and fragments, however, primary cultures tend to first lose several of their in vivo metabolic properties during culture, and second to have only a limited life span (days to weeks). Moreover, establishing such primary cultures is a time-consuming and laborious procedure. For that reason many studies have been carried out on renal cell lines, which are easy to cultivate in large quantities and which have an unlimited life span. Unfortunately, none of the lines display a state of differentiation comparable to that of freshly isolated cells or their primary cultures. Most often they lack expression of key functions (e.g., gluconeogenesis or organic anion transport) of their in vivo correspondents. Therefore, the use of cell lines for assessment of nephrotoxic mechanisms will be limited to those functions the lines express. Upcoming molecular biology approaches such as the transduction of immortalizing genes into primary cultures and the utilization of cells from transgenic animals may in the near future result in the availability of highly differentiated renal cells with markedly extended life spans and near in vivo characteristics that may facilitate the use of renal cell culture for routine screening of nephrotoxins.ImagesFigure 1Figure 2

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“…This is especially so with renal disease, as it is difficult to diagnose at an early stage when causality could be more clearly understood. quantities of metabolic energy for renal function (4,5 (8)(9)(10)(11). In addition, intracellular concentrations of reduced glutathione (GSH) and GSH-dependent enzymes are highest in this nephron segment (8).…”

Section: Introductionmentioning

confidence: 99%

“…quantities of metabolic energy for renal function (4,5 (8)(9)(10)(11). In addition, intracellular concentrations of reduced glutathione (GSH) and GSH-dependent enzymes are highest in this nephron segment (8). Therefore, injuries that alter cellular redox state, such as oxidative stress during ischemia-reperfusion injury, will vary along the nephron.…”

Section: Introductionmentioning

confidence: 99%

Nephrotoxicity Testing in Vitro: What We Know and What We Need to Know

Pfaller¹,

Gstraunthaler²

1998

Environmental Health Perspectives

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The kidney is affected by many chemicals. Some of the chemicals may even contribute to endstage renal disease and thus contribute considerably to health care costs. Because of the large functional reserve of the kidney, which masks signs of dysfunction, early diagnosis of renal disease is often difficult. Although numerous studies aimed at understanding the mechanisms underlying chemicals and drugs that target various renal cell types have delivered enough understanding for a reasonable risk assessment, there is still an urgent need to better understand the mechanisms leading to renal cell injury and organ dysfunction. The increasing use of in vitro techniques using isolated renal cells, nephron fragments, or cell cultures derived from specific renal cell types has improved our insight into the molecular mechanisms involved in nephrotoxicity. A short overview is given on the various in vitro systems currently used to clarify mechanistic aspects leading to sublethal or lethal injury of the functionally most important nephron epithelial cells derived from various species. Whereas freshly isolated cells and nephron fragments appear to represent a sufficient basis to study acute effects (hours) of nephrotoxins, e.g., on cell metabolism, primary cultures of these cells are more appropriate to study long-term effects. In contrast to isolated cells and fragments, however, primary cultures tend to first lose several of their in vivo metabolic properties during culture, and second to have only a limited life span (days to weeks). Moreover, establishing such primary cultures is a time-consuming and laborious procedure. For that reason many studies have been carried out on renal cell lines, which are easy to cultivate in large quantities and which have an unlimited life span. Unfortunately, none of the lines display a state of differentiation comparable to that of freshly isolated cells or their primary cultures. Most often they lack expression of key functions (e.g., gluconeogenesis or organic anion transport) of their in vivo correspondents. Therefore, the use of cell lines for assessment of nephrotoxic mechanisms will be limited to those functions the lines express. Upcoming molecular biology approaches such as the transduction of immortalizing genes into primary cultures and the utilization of cells from transgenic animals may in the near future result in the availability of highly differentiated renal cells with markedly extended life spans and near in vivo characteristics that may facilitate the use of renal cell culture for routine screening of nephrotoxins. -Environ Health Perspect 1 06(Suppl 2):559-569 (1998). http://ehpnetl.niehs.nih.gov/docs/1998/Suppl-2/ 559-569pfaller/abstract.html

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Biochemical Characterization of Individual Nephron Segments

Abstract: The sections in this article are: Biochemical Basis of Active Tubular Transport Biochemical Mechanisms of Hormone Action Cyclic AMP as Intracellular Messenger of Hormones Inositol Polyphosphates, Diacylglycerol, and Ca 2+ as Hormone Messengers … Show more

Cited by 6 publications

References 298 publications

Determination of Choline Dehydrogenase Activity along the Rat Nephron

Determination of Choline Dehydrogenase Activity along the Rat Nephron

Nephrotoxicity testing in vitro--what we know and what we need to know.

Nephrotoxicity Testing in Vitro: What We Know and What We Need to Know

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