Lecithin cholesterol acyltransferase (LCAT) appears to be one of the factors controlling the intravascular turnover rate of
cholesterol. LCAT activity in healthy subjects is significantly higher in men than in women of the same relative
body weight, total and free
cholesterol and
triglycerides. In healthy men
sleep deprivation induced a decrease in LCAT activity combined with a decline of serum
cholesterol concentration; consequently, the intravascular turnover rate of
cholesterol did not significantly change. In hypertensive patients the decrease in
cholesterol turnover rate correlated with the degree of
hypertension and the response of blood pressure to medication. Reduced turnover rate of
cholesterol was more frequent in men than in women, in spite of higher plasma
cholesterol concentration in the latter. During a 4-month period of treatment
etiroxate of
hyperlipoproteinemia II and IV, the only significant change in plasma
cholesterol level was a drop observed after the first two weeks; on the other hand, the turnover rate of
cholesterol rose gradually and approached normal values due to a highly increased LCAT activity.
Obesity and diabetes were associated with a high percentage of deviations in the studied parameters of
cholesterol metabolism. The turnover rate of
cholesterol measured three months after acute
myocardial infarction was below normal in 80% of patients, whereas
hypercholesterolemia was manifested in only less than 40%. The results imply that the intravascular turnover rate of
cholesterol estimated by measurement of LCAT activity may be a suitable
indicator of the internal balance of
cholesterol, substantially more delicate and discriminative than a mere determination of the actual plasma concentration of
cholesterol or plasma
lipoprotein. Judging by our observations, deviations in the internal dynamics of
cholesterol may play an important role in the pathogenesis of
coronary atherosclerosis.