AJP - Heart and Circulatory Physiology, Vol 268, Issue 2 759-H766, Copyright © 1995 by American Physiological Society
Cholesterol distribution in rat heart myocytes
H. Shmeeda, D. Petkova and Y. Barenholz
Department of Biochemistry, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Cholesterol oxidase was used to investigate the distribution of free
cholesterol between plasma membrane and intracellular pools in cultured
neonatal rat heart myocytes. Only 20% of the total unesterified cholesterol
was converted to delta 4-cholestenone by cholesterol oxidase in intact
cells. With increasing age in culture and concurrent hypertrophy, there was
an increase in unesterified cellular cholesterol and plasma membrane
cholesterol; their relative distribution remained unchanged. Electron
micrographs of negatively stained samples of day 4 cytosol revealed the
presence of vesicles 50-200 nm in diameter. Cholesterol monohydrate
crystals were found in the cytosol of hypertrophic day 14 cells. Treatment
of day 14 cells with small unilamellar vesicles of egg phosphatidylcholine
reduced plasma membrane and intracellular cholesterol levels, resulting in
the disappearance of the cholesterol monohydrate crystals and the formation
of vesicles smaller than those observed in day 4 cultures.
