Mg+ Flashcards
how is magnesium reabsorbed in the proximal tubule
20%
- paracellularly
- follows Na+ and H2O
how is magnesium reabsorbed in the thick ascending limb
70%
- paracellularly
- depends on uptake of Na+ and K+ via NK2Cl, which depends on the lumen positive voltage of the TAL
how does hypercalcemia affect magnesium reabsorption
hypercalcemia will activate the CaSR, which inactivates the NK2Cl which will then decrease magnesium reabsorption
how is magnesium reabsorbed in the distal tubule
10%
- via TRPM6
- active transport because of the negative potential difference
how does magnesium cross the apical and basolateral membranes in the DT
apical: TRPM6
basolateral: unknown
what is the primary driver of cellular Mg2+ influx in the DT and why
electrical potential; because the concentration of magnesium is the same inside and outside the cell
how does dietary depletion of magnesium increase its reabsorption
increases paracellular permeability of Mg2+
effect of PTH on magnesium
increases reabsorption
effect of metabolic acidosis on magnesium
decreases paracellular permeability of Mg2+
thus decreasing reabsorption
effect of metabolic alkalosis on magnesium
increases paracellular permeability of Mg2+
thus increasing reabsorption
effect of ECF expansion on magnesium
decreases reabsorption
effect of ECF contraction on magnesium
increases reabsorption
what are the clinical symptoms of magnesium depletion (7)
migraines depression epilepsy SIDS (maybe) arrhythmia preeclampsia muscle cramps
where is magnesium stored
50% in bone
49% in ICF (especially muscle)
1% ECF
