The topic of this review is the lipidic part of the sarcolemma, the plasma membrane of the myocardial cell, and its role in (dis)function of the cardiomyocyte. First the isolation of the sarcolemma and its
lipid composition are discussed. These
phospholipids are not randomly distributed over the two monolayers of the
lipid bilayer and negatively charged
phospholipids are exclusively present in the cytoplasmic leaflet of the sarcolemma, which also contains the majority of
phosphatidylethanolamine. This distribution is most likely caused by an active transport of these
lipids and by an interaction of the headgroup of these
lipids with the cytoskeleton. Subsequently the physicochemical properties of sarcolemmal
phospholipids are discussed, where it is shown that certain
phospholipids prefer non-bilayer phases, and the effects of sarcolemmal
phospholipids on trans-sarcolemmal ion fluxes and
calcium compartmentation are discussed. In the second part the effect of
ischemia on sarcolemmal
phospholipids is discussed with regard to: transbilayer distribution, hydrolysis, lateral distribution and sarcolemmal bilayer stability. In our view, onset of
ischemia initiates a sequence of events leading to a loss of normal sarcolemmal
phospholipid distribution with an outward migration of
phosphatidylethanolamine. There follows, as
ischemia progresses, loss of sarcolemmal bilayer stability due to the expression of the non-bilayer behavior of
phosphatidylethanolamine, leading to irreversible disruption of the sarcolemma and cell death.