renal metabolism Flashcards
the only place in the body where glycolysis does NOT occur under any conditions
PCT
during starvation, renal gluconeogenesis produces _____% of total glucose
40% (other 60% produced by liver)
what is the substrate used for renal gluconeogenesis
glutamine
where does renal gluconeogenesis occur
PCT cells
(no glycolysis, so no reciprocal regulation needed)
what are the substrates used for hepatic gluconeogenesis
alanine
lactate
glycerol
during the first 24 hrs of acidosis, renal ammoniagenesis increases by _____
50%
3 mechanisms for increase in renal ammoniagenesis during acidosis, & overall net result of these
-increase in [plasma glutamine]
-increase in renal uptake of plasma glutamine
-increase in renal glutaminase & GDH activity
net result: increase in HCO3- & NH3 production to compensate for acidosis
how is ammonia (from amino acid degradation) disposed
urea cycle in liver (in periportal hepatocytes)
one nitrogen in urea is from _____, second nitrogen in urea is from _____
free ammonia (from glutamate)
aspartate
does glutamate directly participate in urea cycle
NO
overall goal of communication between periportal & perivenous hepatocytes
to ensure that no ammonia escapes (all is eventually made into urea -> degraded in urea cycle)
glutamine consumption done by what cells
periportal hepatocytes
glutamine production done by what cells
perivenous hepatocytes
rates of glutamine consumption & glutamine production in hepatocytes under NORMAL conditions
they’re equal
rates of glutamine consumption & glutamine production in hepatocytes during metabolic ACIDOSIS
glutamine consumption decreases
glutamine production increases
molecules used for ATP production by PCT cells
glutamine
fatty acids
ketone bodies
glutamine catabolism through TCA cycle can also be used for _____
ATP production in PCT cells
% of ATP produced from glutamine in PCT cells during FED state
15%
% of ATP produced from glutamine in PCT cells during FASTING state
25%
% of ATP produced from glutamine in PCT cells during ACIDOSIS
40%
% of ATP produced from fatty acids in PCT cells during FASTING state
60%
PCT cells are 100% reliant on what form of metabolism, & why
oxidative metabolism
bc they can’t do glycolysis
parts of medulla / cortex that are aerobic / anaerobic
anaerobic: inner medulla
aerobic: outer medullae & cortex
