Origin and transport of the A-I and arginine-rich apolipoproteins in mesenteric lymph of rats.
Transport of apolipoprotein A-I and argininerich apolipoprotein in mesenteric lymph was examined in rats given constant intraduodenal infusions of saline, glucose in saline, or emulsified fat. Lymph flow in all groups was constant from 5 to 50 hr after beginning the infusions. Lymphatic transport of triglycerides was about 20-fold greater and transport of apoprotein A-I was about twofold greater in fat-infused rats than in the other two groups. In each group transport of apoprotein A-I bore a significant positive relationship to transport of triglycerides. Lymphatic transport of the arginine-rich apoprotein was only 6-12% of that of apoprotein A-I and was more closely related to lymphatic transport of total protein than to that of triglycerides. In fat-infused rats given [(3)H]lysine intraduodenally, about two-thirds of the (3)H in the chylomicron proteins was in apoprotein A-I and only about 1% was in the arginine-rich apoprotein. Estimated specific activity of chylomicron proteins was highest for apoprotein A-I and apoprotein A-IV, and lowest for the arginine-rich apoprotein and proteins of low molecular weight (mainly C apoproteins). In fat-infused rats given constant intravenous infusions of radioiodinated high density lipoproteins from blood plasma, the specific activity of apoprotein A-I in lymph chylomicrons was only about 5% of that of apoprotein A-I in blood high density lipoproteins, indicating that more than 90% of the apoprotein A-I in chylomicrons was synthesized in the intestine. From these and other data it is concluded that both the intestine and liver are significant sources of apoprotein A-I whereas only the liver synthesizes significant amounts of the arginine-rich apoprotein.
D000818:Animals; D001053:Apolipoproteins / Q000378:metabolism*; D001120:Arginine; D001692:Biological Transport; D002914:Chylomicrons / Q000378:metabolism; D004041:Dietary Fats; D008075:Lipoproteins, HDL / Q000378:metabolism; D008196:Lymph / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008297:Male; D008643:Mesentery / Q000378:metabolism*; D051381:Rats; D014280:Triglycerides / Q000378:metabolism
D001053:Apolipoproteins; D002914:Chylomicrons; D004041:Dietary Fats; D008075:Lipoproteins, HDL; D014280:Triglycerides; D001120:Arginine; D008239:Lysine