QuestionSBA
QuestionChoice
Glutamine is metabolised to glutamate then a-ketoglutarate, releasing ammonium at each step. A-ketoglutarate is then metabolised to malate, releasing bicarbonate. Malate is then metabolised through the Krebs cycle and gluconeogenesis into glucose, releasing more bicarbonate in the process. The bicarbonate released can be reabsorbed to alkalinise the blood while the ammonia and protons produced are excreted and trapped as ammonium in the lumen.
10001211
a
Used in bicarbonate synthesis
QuestionChoice
Potassium is reabsorbed in an unregulated manner in the proximal convoluted tubule by potassium-chloride co-transporters, in the thick ascending loop of Henle using NKCC2, and in the collecting ducts using potassium-proton exchanging ATPases. It is mainly in the distal convoluted tubule where potassium is excreted under the control of aldosterone through the action of the basal sodium-potassium exchanger ATPase and apical potassium channels. Glutamine does not have a significant role.
10001214
d
Used to secrete potassium
QuestionChoice
Although glutamine is used in protein translation, this is a function common to all metabolically active cells and not notably more important in the proximal convoluted tubule.
10001212
b
Used to build proteins
QuestionChoice
Sodium is reabsorbed in an unregulated manner under the power of the basolateral sodium-potassium exchanger ATPase in the thick ascending limb (using apical NKCC2). Sodium is also reabsorbed in an unregulated manner in the proximal convoluted tubule using apical SGLT-1/2, and in a regulated manner due to angiotensin 2 which increases the expression of apical sodium-proton exchangers. Sodium is also reabsorbed under the control of aldosterone through the induction of expression of ENaC on the apical membranes of distal convoluted tubule cells. Glutamine does not have a significant role.

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10001215
e
Used to reabsorb sodium
QuestionChoice
Fatty acids are the main source of energy in the proximal convoluted tubule. It is in the gastrointestinal epithelium where glutamine is metabolised extensively as an energy source as well as to provide ammonium for the synthesis of other amino acids.
10001213
c
Used as the main source of energy
Concept
Chapter
2693
3895
Bicarbonate re-absorption
Topic
168
Renal Physiology
12789
Glutamine is particularly important in the proximal convoluted tubule for which of the following reasons?
a