Decreased lecithin:cholesterol acyltransferase activity in the plasma of hypercholesterolemic pigs

Lecithin:cholesterol acyltransferase (LCAT) activity levels were determined, as function of plasma total cholesterol (TC) in 13 normocholesterolemic (TC less than 85 mg/dL) and in 28 hypercholesterolemic (TC greater than 98 mg/dL) pigs. The normocholesterolemic group consisted of pigs that carried apo-B allelic genes other than Lpb5 and or Lpb8. The hypercholesterolemic group consisted of Lpb5/x and Lpb5/8 heterozygous and Lpb5/5 homozygous animals. The data reported in this study show that the LCAT activity in the plasma of hypercholesterolemic (HC) pigs (79 +/- 43 units) was significantly lower (p less than 0.0005) compared to the normocholesterolemic controls (175 +/- 45 units). Furthermore, LCAT activity was positively correlated with TC in the normocholesterolemic group (r = +0.54; p less than 0.05), whereas it was negatively correlated with TC in the hypercholesterolemic group (r = -0.73; p less than 0.001). Additional data obtained from incubation experiments suggest that the lower LCAT activity in hypercholesterolemic pigs may be due, at least in part, to inhibition of LCAT activity by components found in the lipoprotein-deficient fractions of the plasma of hypercholesterolemic pigs.