The role of magnesium in the generation and therapy of benign muscle cramps. Combined in-vivo/in-vitro studies on rat phrenic nerve-diaphragm preparations.
Rats received during 3 weeks a Mg-deficient or a Mg-rich diet; Mg-deficient animals revealed hypomagnesemia, cellular K-depletion and Ca-loading. Phrenic nerve-diaphragm preparations were studied; the physiological Tyrode solution contained low or high-Mg concentrations and 0 or 12 mmol lactate/L. Electric stimulation (indirect via the nerve or direct) produced tetanic contractions and increased force at increasing stimulation frequencies. Significantly lower frequencies were needed to elicit these effects when intra- and extracellular Mg levels were low, in comparison to plentiful Mg supply. Comparing unstimulated and stimulated diaphragmatic tissue electrolyte concentrations revealed tissue losses of Mg, K Ca from stimulated tissues which were less pronounced when Mg supply was optimal. These data support the empiric finding that relief from muscle cramps is promptly offered by Mg supplements.
Schindler
R
R
Department of Pharmacology and Toxicology of Nutrition, University of Hohenheim, Stuttgart, Germany.
Thöni
H
H
Classen
H G
HG
D000818:Animals; D003964:Diaphragm / Q000503:physiopathology*; D004032:Diet; D004573:Electrolytes / Q000378:metabolism; D066298:In Vitro Techniques; D008274:Magnesium / Q000502:physiology* / Q000627:therapeutic use*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009135:Muscular Diseases / Q000188:drug therapy* / Q000503:physiopathology*; D010791:Phrenic Nerve / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D004573:Electrolytes; D008274:Magnesium