The Incorporation of Plasma Free Fatty Acids Into Plasma Triglycerides in Man*

Abstract

Plasma triglycerides (neutral fat) may be divided into 1) that portion which is present during the fasting state and 2) that which, after ingestion of fat, is added to and temporarily augments the fasting level of triglycerides.The present investigation deals with the relationship of plasma free fatty acids (plasma FFA) to fasting plasma triglycerides (plasma TG) in man. From these observations a quantitative assessment of the amount of plasma FFA converted to plasma TG will be presented. The data also permit calculations which suggest that plasma FFA may be the major source of fasting plasma TG. METHODSTwo types of studies were carried out in male patients without known abnormalities of fat metabolism.1. Non-reinjection experiments. After an overnight fast of 15 hours, 9 subjects were given 0.004 to 0.008 mc albumin-bound palmitic acid-i-C1' intravenously either by single injection or by 2-hour constant infusion. Two individuals received 0.00585 mc of albumin-bound oleic acid-i-C1' and another 0.00597 mc of stearic acid-1-C14.During the day of the study the subjects were permitted no breakfast, a nonfat lunch, and an unrestricted supper. Venous blood samples were drawn at appropriate intervals over a period of 24 hours after administration of fatty acid C1' for determination of neutral fat activity. Two-ml aliquots of plasma were extracted by the method of Dole (1). Eight ml of the upper phase, representing 1.85 ml of plasma, was transferred to a separate tube. Ten ml of 0.1 N NaOH in 50 per cent ethanol was added, according to the method of Borgstrbm (2), in order to * This investigation was supported in part by a grant from the Life Insurance Medical Research Fund; by a research grant H-4807; a training grant, HTS-5369, from the National Heart Institute, Public Health Service; a research grant, A-4535-MET, from the National Institutes of Health, Public Health Service; a research grant for July 1960-61, from the North Carolina Heart Association; and by the Regional Center for the Study of Aging, Duke University. remove fatty acids from the upper phase. The upper phase and its contents were then transferred quantitatively to liquid scintillator vials, dried with a stream of warm air from a hair dryer, and redissolved in 5 ml of phosphor solution for counting in a Packard Tri-Carb liquid scintillation spectrometer. Along with plasma glycerides, the extracts contained cholesterol, cholesterol esters and a small amount of phospholipid. These would also be expected to become labeled; therefore, it was necessary to determine the amount of activity in the various plasma lipids present in the extracts at various times after injection of C4-labeled fatty acids. This was done by means of silicic acid chromatography using the method of Hirsch and Ahrens (3) without modification. Plasma palmitic acid-l-C1 activity was measured as previously described (4).The experimental plan required a method which would permit easy and reproducible determinations on a large number of samples. The method selected for measuring plasma T...

Plasma Free Fatty Acid Storage in Subcutaneous and Visceral Adipose Tissue in Postabsorptive Women

“…Therefore, some FFA tracer stored in visceral fat may have arrived via the VLDL-TG/LPL pathway, although our results suggest that the contribution of this pathway was probably small. First, in the palmitate protocol, we found that only ϳ4% of the FFA tracer traversed the VLDL-TG pool over 4.5-9.5 h, which is consistent with previous reports (18,30). This was accompanied by a small and nonsignificant increase in FFA tracer accumulation in subcutaneous fat from 30 -45 min to 24 h after the tracer bolus (Table 3).…”

“…For practical purposes, we used different FFA tracers in two protocols: the oleate protocol and the palmitate protocol. The two tracers should give comparable results because they give similar estimates of plasma FFA kinetics (16) and have similar fractional extraction across adipose tissue (17) and similar incorporation into plasma triglycerides (18). Because these two fatty acids are the major fatty acids found in plasma, their metabolism can be taken to be representative of the bulk of plasma FFA.…”

Inter-relationship between insulin secretion and plasma free fatty acid and triglyceride transport kinetics in maturity onset diabetes and the effect of phenethylbiguanide (Phenformin)

“…These values are comparable to those of l~riedberg et al [21] who used an integration method and those reported by Reaven et al [41], and Nflddli/and Kekki [37] who used the atI glycerol labelling technique. These results encouraged us to use the endogenous labelling technique for its simplicity and convenience.…”

Pressão arterial, respostas metabólicas e autonômicas à insulina e infusão de intralipid® em pacientes chagásicos

“…Friedberg et al 10 have already shown a good correlation between triglycerides and fatty acids in the circulation. Baseline blood pressure and heart rate before ILH infusion were similar in both groups.…”