Inhibition of calcium by magnesium in the contraction of rat aortic smooth muscle. I. Mathematical model of calcium and magnesium binding.
A mathematical model of the effect of calcium and magnesium binding on muscle tension was developed. The model was tested on aortic smooth muscle tissue obtained from rats fed magnesium-sufficient (Mg: 650 ppm) and magnesium-deficient (Mg: 4.5 ppm) diets. Ca2+ binding constants of 2.51 X 10(3) and 2.3 X 10(3) M-1 were obtained for aortae from magnesium-sufficient and magnesium-deficient rats, respectively. The corresponding Mg2+ binding constants were 0.6 X 10(3) and 0.4 X 10(3) M-1. The data indicate that Mg2+ is a competitive inhibitor of Ca2+ in tension development in rat aortic smooth muscle tissue.
D000818:Animals; D001013:Aorta, Thoracic; D001667:Binding, Competitive; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008433:Mathematics; D008954:Models, Biological; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction
D008274:Magnesium; D002118:Calcium