Gene/Protein
Disease
Symptom
Drug
Enzyme
Compound
Pivot Concepts:
Gene/Protein
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Target Concepts:
Gene/Protein
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Query: EC:1.4.1.2 (
glutamate dehydrogenase
)
4,380
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
A method for measurement of
glutamate dehydrogenase
(
GDH
) activity in single renal tubules was employed to determine the distribution and regulation of
GDH
in tubule segments. Fresh microdissected tubules from collagenase-treated kidneys were permeabilized by hyposmotic shock and freezing. The rate of conversion of alpha-ketoglutarate, NH4+, and NADH to glutamate and NAD was measured at 37 degrees C fluorometrically. Very high activities were found in proximal tubule segments (150-210 pmol.min-1.mm tubule length-1), intermediate values (40-90 pmol.min-1.
mm-1
) in distal convoluted tubules, cortical thick ascending limbs, connecting tubules, medullary thick ascending limbs, and lower values (5-30 pmol.min-1.
mm-1
) in cortical collecting ducts, inner medullary collecting ducts, outer medullary collecting ducts, outer medullary thin limbs, and inner medullary thin limbs. To determine the effects of acid-base loading on
GDH
activity, 0.28 M NH4Cl (acid) or 0.28 M NaHCO3 (alkali) was added to the animals' drinking water for 7 days. Acid intake by the rats increased
GDH
activity in S1 and S2 proximal tubules by threefold, with no effect in other segments, including S3 proximal tubules. Alkali intake decreased
GDH
activity in the S3 proximal tubule by 40%, with no effect in other segments. We conclude that
GDH
activities are highest in proximal tubule segments and are regulated only in proximal tubule segments. Thus the results are consistent with the view that the proximal tubule is the chief site of the regulated production of ammonium in the kidney.
...
PMID:Glutamate dehydrogenase activities in microdissected rat nephron segments: effects of acid-base loading. 237 92
