it has generally been believed that the physiological roles for magnesium ions ( mg2+ ) in cardiac and vascular smooth muscle are limited to regulation of contractile proteins , sarcoplasmic reticular membrane transport of calcium ions ( ca2+ ) , cofactor in atpase activities and metabolic regulation of energy-dependent cytoplasmic and mitochondrial pathways .
C0010834
cytoplasmic
C0026237
mitochondrial