Metabolic CO2 production by isolated single pieces of rat distal nephron segments
| Autor: | Annette Hus-Citharel, François Morel, Françoise Le Bouffant |
|---|---|
| Rok vydání: | 1984 |
| Předmět: |
Physiology
Bicarbonate Clinical Biochemistry Nephron Biology Acetates In Vitro Techniques Kidney Tubules Proximal chemistry.chemical_compound Physiology (medical) parasitic diseases medicine Animals Receptor Kidney Tubules Distal Kidney Temperature Substrate (chemistry) Metabolism Nephrons Carbon Dioxide Molecular biology Rats Tubule medicine.anatomical_structure Glucose Biochemistry chemistry Collagenase Lactates Loop of Henle medicine.drug |
| Zdroj: | Pflugers Archiv : European journal of physiology. 401(4) |
| ISSN: | 0031-6768 |
| Popis: | A method is described which allowed in-vitro measurements of metabolic CO2 production from [U-14C]-substrates by single pieces of kidney tubules. The tubules were isolated by microdissection from collagenase treated rat kidneys. Single pieces of various distal nephrons portions were incubated in 1 μl of bicarbonate free minimum essential medium containing the required [U-14C]-substrate (about 0.2 μCi per sample), and the14CO2 produced was continuously trapped into a 2-μl KOH droplet. The KOH droplets were replaced every 30 min. Metabolic CO2 production from the labelled substrate used was calculated as picomoles CO2 per mm of tubular length per minute, by dividing the KOH radioactivity by the specific radioactivity per carbon of the substrate present in the incubate ([U-14C] plus cold substrate concentrations). Under these conditions, it was established that single pieces of tubule could sustain almost constant CO2 production for at least 2 h at 31° C. Experiments testing four different conditions with five to six replicate samples per condition were performed in order to compare oxidative metabolism in medullary (MAL) and cortical (CAL) thick ascending limbs, medullary (MCT) and cortical (CCT) collecting tubules and, in a few instances, proximal convoluted tubules (PCT) and early distal convoluted tubules (DCT). The results show that: a) PCT poorly oxidized glucose; b) in contrast, CAL, MAL, CCT, MCT and DCT oxidized efficiently glucose and lactate; c) however, when both substrates were offered simultaneously, CAL and MAL oxidized lactate preferentially to glucose, whereas CCT oxidized glucose preferentially to lactate; d) when each segment was offered its preferential substrate, the rate of oxidative metabolism was observed to vary from about 4 to 0.5 pmol·mm−1·min−1 according to the following sequence: DCT>MAL>CAL≈PCT>CCT ≈MCT. |
| Databáze: | OpenAIRE |
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