Characterisation of Ca2+ transport activity by white adipose tissue mitochondria (original) (raw)

Ca2' transport in mitochondria isolated from rat white adipocytes has been examined and many of the properties found to be similar to those reported for mitochondria isolated from rat liver. Ca" transport is ruthenium red-sensitive (Ki -5 pmol . mg protein-'), the affinity for free Ca2' is high (Km -3.3 PM) and the V,, is 135 nmol Ca2+ .min-'.mg protein-' at 4°C with 0.2 mM Pi present. Ca" transport is stimulated by increasing the medium [Pi], and is inhibited when ATP or Mg2+ is added to the incubation system and in contrast to brown adipocyte mitochondria, Ca2' efflux is not promoted by Na+. White adipocyte mitochondria may play a role in the regulation of total cell calcium in this tissue.