Studies on fat digestion, absorption, and transport in the suckling rat. IV. In vivo rates of triacylglycerol secretion by intestine and liver.

The rate of triacylglycerol entry into plasma in 14- to 15-day-old suckling rats was measured using the Triton WR1339 method. When the pups were left with the mother and allowed to nurse continually, the rate was 31.8 +/- 2.3 mumol/hr per rat. If the pups were removed from the mother with full stomachs and kept in a warm box at 30-32 degrees C, the rate was 12.5 +/- 1.5 mumol/hr per rat. The rate of triacylglycerol output from the intestine measured in lymph duct-cannulated animals (kept in a warm box at 30-32 degrees C) was 14.9 +/- 2.7 mumol/hr per rat. Triton treatment of lymph duct-cannulated animals caused only a small increase in plasma triacylglycerol concentration (less than 2 mumol/hr per rat). These data suggest that nearly 100% of plasma triacylglycerol arises from intestinal input in the suckling rat.