Development of solute transport in rabbit proximal tubule. III. Na-K-ATPase activity.

G. J. Schwartz, Andrew Evan

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Abstract

HCO-3 transport (JHCO-3) in early juxtamedullary proximal convoluted tubules isolated from infant rabbits during the 1st 3 wk of life is about one-third that in tubules obtained from adults. A rapid increase in transport ensues during wk 4 through 6, so that near-mature levels are attained by the end of this time. Because the pattern for development of glucose absorption was similar and because both HCO-3 and glucose absorption are driven by the lumen-to-cell Na+ flux, the activity of Na-K-ATPase (the Na+-extruding pump) was considered to be a critical mediator. A kinetic microassay (which couples ATP hydrolysis to NADH oxidation) allowed the measurement of Na-K-ATPase and ouabain-insensitive ATPase on the same tubular segment. Three to nine early juxtamedullary proximal convoluted tubules were obtained after collagenase treatment of the kidney and four to six rabbits were studied at each week of life. The mean activity of Na-K-ATPase during the 1st wk of life was 44.5 +/- 3.5 pmol X min-1 X mm-1, one-third of the adult level. During an interim period of development (2-6 wk), enzyme activity gradually reached 60% of adult levels (76.3 +/- 3.0 at 6 wk), while transport of HCO-3 and glucose, studied previously in other animals, attained mature rates. Only in the 7th wk did the enzyme activity reach that of the adult (106.8 +/- 6.8 in wk 7 vs. 128.4 +/- 14.0 in adult rabbits).(ABSTRACT TRUNCATED AT 250 WORDS)

Original languageEnglish
JournalThe American journal of physiology
Volume246
Issue number6 Pt 2
StatePublished - Jun 1984
Externally publishedYes

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Rabbits
Glucose
Collagenases
Ouabain
Enzymes
NAD
Adenosine Triphosphatases
Hydrolysis
Adenosine Triphosphate
Kidney
sodium-translocating ATPase
Therapeutics

ASJC Scopus subject areas

  • Medicine(all)

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Development of solute transport in rabbit proximal tubule. III. Na-K-ATPase activity. / Schwartz, G. J.; Evan, Andrew.

In: The American journal of physiology, Vol. 246, No. 6 Pt 2, 06.1984.

Research output: Contribution to journalArticle

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