167b Mg

Question 1

Mg - fxns

Answer 1

very widespread fxns

enzyme fxn (ATP, GTP); membrane fxn; antomic structure

Question 2

Mg - locaiton in body

Answer 2

mostly intracellular

Question 3

Mg - serum ionized Mg reflects what?

Answer 3

intracellular Mg

not related to total Mg (which is what is measured)

Question 4

Mg - dry vs wet

Answer 4

dry = smallest
wet = largest ion

Question 5

Mg - aq solution and fxn

Answer 5

very rigid structure in water - 2 layer h2o shell

perfect for binding for ATP - stablizes it and helps hydrolyses during enzyme rxns

anyting that is driven by ATP required Mg as a cofactor

Question 6

MgSO4 and torsade de pointes

Answer 6

long QT –> polymorphic VT

Mg regulates the delayed potassium rectifier channel (ether a go go channel)

modulates voltage-dependent activation of channel

Question 7

Mg and renal K wasting

Answer 7

Mg inhibits ROMK (aldosterone K channel)

thus Mg inhibits K loss in urine

hypoMg acts like aldosterone

Question 8

Mg and prenancy

Answer 8

preg chicks loss intracellar Mg

needed to regulate SBP (inverse corelation)

Question 9

hyperMg

Answer 9

low RR

cause is iatrogenesis

Question 10

Mg and CV Risk

Answer 10

low Mg reduces Na/K ATPase

increases intraceullarl Na and decreases K

high Mg = lower CV risk

Question 11

Mg and Ca channel

Answer 11

Mg blocks influx of Ca –> hypo causes vasoconstriciton

high Mg = lower blood pressure

Question 12

Mg and insulin

Answer 12

Mg –> activates tyrosine kinase –> P insulin receptor –> increased insulin sensitivity

(hypoMg –> metabolic syndrome)

Question 13

Mg balance and alcoholism

Answer 13

alcohol increases Mg loss
diuretics
cyclosporin

Question 14

problem with Mg-oxide?

Answer 14

no bioavailabilty