The opposite effects of magnesium and calcium on the contraction of the guinea-pig ventricular myocardium in dependence on the sodium concentration.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology*; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects; D012964:Sodium / Q000502:physiology*
D012964:Sodium; D008274:Magnesium; D002118:Calcium