The major characteristics of the Ca2+ binding of isolated cardiac sarcolemma can be reproduced by the Ca2+ binding of vesicles prepared from phospholipids extracted from sarcolemma. The extracted phospholipid vesicles account for a large fraction of the sarcolemmal Ca2+ binding which suggests that other sarcolemmal components (e.g. protein and sialic acid) bind lesser amounts of Ca2+. Removal of sialic acid (57%) with neuraminidase decreases Ca2+ binding of sarcolemma by about 13%. The ability of different pure phospholipid vesicles to bind Ca2+ is assessed. This, together with sarcolemmal phospholipid analysis, suggests that phosphatidylserine and phosphatidylinositol are important Ca2+-binding molecules in cardiac sarcolemma. The Ca2+ binding of vesicles prepared from pure phospholipids mixed in the relative proportion in which they are present in sarcolemma is similar to that of vesicles of extracted sarcolemmal phospholipids. The Ca2+ binding of cardiac sarcolemma has previously been correlated with myocardial contractility. It is speculated that phospholipids have a role in cardiac excitation-contraction coupling. In addition the use of deoxyribonuclease in the isolation of sarcolemmal membranes from rabbit ventricles is described. Use of this enzyme results in an increase in both the purity and yield of sarcolemma in a fraction found at a density of 1.11 g/ml on a sucrose gradient.
|Original language||English (US)|
|Number of pages||15|
|Journal||Journal of Molecular and Cellular Cardiology|
|State||Published - 1980|
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine