title: Calcium-accumulating properties of subcellular fractions of bovine vascular smooth muscle.
abstract: This study examined the calcium transport properties of two subcellular fractions of bovine aorta obtained by differential centrifugation. The vesicular fraction had a high-affinity (Km = 1.05 X 10(-6)M) calcium transport mechanism which could be potentiated by using the calcium-precipitating anion, oxalate. The mitochondria-enriched fraction's calcium transport system had a lower affinity for calcium than did that of the vesicular fraction. The calcium capacity of the vesicular fraction was determined by comparing the steady-state calcium uptake in the presence of oxalate in the whole homogenate with the same uptake by the vesicular fraction alone. A calcium capacity of about 100 mumoles Ca2+/kg aorta was obtained. It is concluded that the vesicular fraction has  all of the properties of a major site of subcellular calcium regulation in vascular smooth muscle.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001011:Aorta / Q000648:ultrastructure*; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D004533:Egtazic Acid / Q000494:pharmacology; D007700:Kinetics; D008931:Mitochondria, Muscle / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism / Q000648:ultrastructure*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D004533:Egtazic Acid; D000251:Adenosine Triphosphatases; D002118:Calcium