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 exagge rated post prandial lipaemia and fasting hypertriglyceridaemia. This s tudy evaluated whether oral and intravenous fat tolerance tests are ap propriate for the in vivo analysis of chylomicron clearance in dogs. P lasma and chylomicron triglyceride concentrations were measured in eig ht beagles after the administration of a cream-based meal of 2.35 g fa t kg(-1) bodyweight. The changes in each parameter were determined chi efly by the activity of lipoprotein lipase, which was measured in plas ma collected after the intravenous injection of heparin and did not ap pear to be influenced by intestinal fat absorption. The inclusion of r etinyl palmitate in the meal provided additional information on the me tabolic fate of chylomicron remnants. After the intravenous injection of 0.1 g Intralipid kg(-1) bodyweight, there was an initial linear dec ay in plasma triglyceride concentrations that represented the maximal elimination rate K-1. This was followed by a second exponential compon ent so that the plasma triglyceride concentration returned to baseline by 60 minutes. Lipoprotein lipase was the major determinant of KI and the area under the curve of plasma triglycerides.