Lewanczuk RZ
Magnesium supplementation increases blood pressure in
spontaneously hypertensive rats
12th Annual ASH Meeting
Am J Hypertens
(Apr) 10:98A 1997
Assuming that the SHR rat models human low renin hypertension, the authors
tested the
hypothesis that Mg supplementation would correct hypertension which has been
attributed to low intracellular Mg in these rats.
Two groups of 12 animals (each, presumably) of unspecified sex were fed
respectively a standard diet containing 0.4% Mg and a high 2% Mg diet for
one month at the end of which intacellualr pH and Mg in RBCs were measured
by NMR, platelets intracellular Ca was measured by Fura-2, mean arterial
blood pressure (MAP) was measured by direct cannulation and parathyroid
hypertensive factor (PHF) was measured by a bioassay.
Contrary to the initial hypothesis, MAP was elevated in the SHR rats fed a
high Mg diet
relative to those receiving the lower Mg diet (MAP 179 mm Hg vs. 156,
respectively).
Intracellular Mg levels were elevated in the rats fed a high Mg diet, whereas
pHi and
intracellular calcium were unchanged. The authors conclude that if SHR model
low renin
hypertension in man, the results may have relevance to the human condition.
Comment: It is worth noting though that two studies in man have
suggested that Mg
supplementation is unlikely to lower blood pressure in adults with high
normal BP (
Yamamoto et al, Ann Epidemiol 5:96-107, 1995) or to alter
it in
untreated
mild-to-moderate hypertensives (
Plum-Wirell et al , Magnes Res 7:277-283, 1994). It thus
appears that experimental animal as well as human sudies agree on the lack
of a beneficial effect of magnesium supplementation on hypertension and the
above study suggests that, if anything, it might be detrimental.
(Samy S. Iskandar, MBBCh, PhD, Bowman Gray School of Medicine, Winston-
Salem, NC)
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12th Annual ASH Meeting
H: Non drug therapy :
Dietary/electrolyte therapy