The metabolic fate of high density lipoprotein (HDL) in the diabetic rat.

Diabetic rats, pre-fed and maintained on a sucrose-rich diet, have marked hyperlipoproteinaemia, with an increase in both very low density (VLDL) and high density lipoproteins (HDL). HDL obtained from both diabetic and non-diabetic rats and labelled with 125I or 135I was injected simultaneously into diabetic and non-diabetic rats. The half life of the two HDL preparations was similar in both diabetic and non-diabetic rats and ranged between 11.4 to 12.0 hours. A-I apolipoprotein had a disappearance rate parallel to the whole HDL, in contrast to the apo-C peptides which had a faster rate of removal. Although the fractional catabolic rate (FCR) of HDL preparations was slower in the diabetic rats, there was a 16% increase in the calculated synthetic rate (SR) of HDL-protein. These observations could explain the increased plasma HDL levels in the sucrose-fed, streptozotocin-induced diabetic rat.