Membrane fractionation of canine aortic smooth muscle: Subcellular distribution of calcium transport activity

C. Y. Kwan, C. R. Triggle, A. K. Grover, R. M.K.W. Lee, E. E. Daniel

Research output: Contribution to journalArticle

29 Citations (Scopus)


Various subcellular membrane fractions were isolated from dog aortic smooth muscle by conventional differential centrifugation followed by isopycnic centrifugation on a sucrose density gradient. These subcellular fractions were characterized by membrane marker enzyme activities, morphological features and the electrophoretic patterns on a sodium dodecyl sulfate polyacrylamide gel. Our results showed that the microsomal membrane fraction isolated by differential centrifugation was very heterogeneous and contained substantial amount of plasma membranes which could be further enriched as a light density fraction on the sucrose density gradient. The subcellular distribution of Ca2+ binding in the absence of ATP and Ca2+ transport in the presence of ATP closely paralleled the distribution of plasma membrane markers. The ATP-supported Ca2+ transport was inhibited by several Ca2+ ionophores, enhanced by inorganic phosphate and oxalate ions and cosedimented toward higher density in a continuous source density gradient with plasma membrane marker enzyme activity in the presence of digitonin. Our present work strongly suggests that plasma membrane is the predominant component of microsomal fraction and responsible for most, if not all, of the azide-insensitive ATP-supported Ca2+ accumulation.

Original languageEnglish
Pages (from-to)747-764
Number of pages18
JournalJournal of Molecular and Cellular Cardiology
Issue number8
Publication statusPublished - Aug 1984



  • Calcium
  • Dog aorta
  • Membrane transport
  • Plasma membrane
  • Vascular smooth muscle

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this