Use of oral and intravenous fat tolerance tests to assess plasma chylomicron clearance in dogs.

The reduced clearance of chylomicrons from plasma results in an exaggerated post prandial lipaemia and fasting hypertriglyceridaemia. This study evaluated whether oral and intravenous fat tolerance tests are appropriate for the in vivo analysis of chylomicron clearance in dogs. Plasma and chylomicron triglyceride concentrations were measured in eight beagles after the administration of a cream-based meal of 2.35 g fat kg-1 bodyweight. The changes in each parameter were determined chiefly by the activity of lipoprotein lipase, which was measured in plasma collected after the intravenous injection of heparin and did not appear to be influenced by intestinal fat absorption. The inclusion of retinyl palmitate in the meal provided additional information on the metabolic fate of chylomicron remnants. After the intravenous injection of 0.1 g Intralipid kg-1 bodyweight, there was an initial linear decay in plasma triglyceride concentrations that represented the maximal elimination rate K1. This was followed by a second exponential component so that the plasma triglyceride concentration returned to baseline by 60 minutes. Lipoprotein lipase was the major determinant of K1 and the area under the curve of plasma triglycerides.