Injection Of Triton WR-1339 Research Articles

Comparative antilipidemic effects of various ethyl 5‐substituted benzofuran‐, 2,3‐dihydrobenzofuran‐, and 3(2H)‐benzofuranone‐2‐carboxylate analogs of clofibrate in a triton hyperlipidemic rat model

The antilipidemic properties of certain benzofuran-, 2,3-dihydrobenzofuran-, and 3(2H)-benzofuranone-2-carboxylate analogs of clofibrate in a hyperlipidemic rat model are described. The hyperlipidemia was induced by intraperitoneal injection of Triton WR-1339. The results were analyzed in light of structural modifications as well as the lipid solubility of substituted compounds as assessed by a consideration of calculated log P values. Comparisons are made between the activity of these compounds and the activity of related cyclic analogs previously reported. Among the various compounds tested, only the 5-C1 and phenylsybstituted dihydrobenzofurans were selective against elevated serum cholesterol levels in this animal model. The data presented support the hypothesis that the cholesterol and triglyceride lowering activity of clofibrate related analogs in this animal model may be separated through a consideration of log P, conformational, and electronic changes. The proposal is advanced that relatively minor structural modification of clofibrate related analogs may lead to compounds which are not only selective in the Triton model but also to compounds which are likely to exert their effects by differing modes of action.

Formation of phagolysosomes containing dextran and Triton WR 1339 in mouse liver.

After injection of Triton WR 1339 and dextran into mice, phagolysosomes containing both compounds were obtained from the liver regardless of the order of injection of these materials. This suggests that phagososomes containing the other material. The recoveries of various lysosomal enzymes differed in phagolysosomes after injection of Triton WR 1339 with or without dextran: recoveries of beta-glucuronidase, beta-N-acetylglucosaminidase and arylsulfatase were high, and that of acid phosphatase was low.

Effect of Exercise on Response of Liver Lipogenic Enzymes to a High Fructose Diet

Meal-fed Long-Evans rats fed a high fructose diet and exercised for 2-hr daily on a treadmill for three days had lower levels of several hepatic lipogenic enzymes (acetyl CoA carboxylase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, malic enzyme and citrate cleavage enzyme) than did sedentary rats pair-fed the diet. Accumulation of triglycerides in plasma following ingestion of a fat-free, high fructose meal and injection of Triton WR-1339, an inhibitor of plasma triglyceride clearance, was not significantly different in the two groups of animals. All of the hepatic lipogenic enzymes measured, with the exception of citrate cleavage enzyme, attained similar levels in the runners as in the controls after 5 days on the high fructose diet. Thus the exercise appeared to affect the time course of the increase in the levels of activity of most of the lipogenic enzymes but not the final steady state levels attained.

Lysosomes of the arterial wall: II. Subcellular fractionation of aortic cells from rabbits with Experimental Atheroma

Cells were isolated from the aortas of control rabbits and of rabbits with experimental atheroma induced by cholesterol feeding. They were homogenized and fractionated by three different techniques relying mainly on differences in equilibrium density of cell particles in sucrose gradients. After cholesterol feeding, the aortic smooth muscle cells transformed progressively into foamy cells. Their protein to DNA ratio was unchanged. The mitochondrial marker cytochrome oxidase and the presumed plasma membrane markers 5′-nucleotidase and leucyl-β-naphthylamidase showed no significant change in specific activity, nor in density distribution, even in severely atheromatous lesions. Only minimal changes were seen for α-glucosidase, an enzyme probably associated largely with microsomes. Catalase was increased up to 7-fold; one-third of this activity was in particles of about 1.18 density, the rest was soluble. The specific activity of all lysosomal acid hydrolases increased with increasing severity of atheroma, up to a little more than 2-fold for N-acetyl-β-galactosaminidase and α-mannosidase, 3- to 4-fold for N-acetyl-β-glucosaminidase, acid phosphatase, and cathepsin C, more than 10-fold for β-galactosidase and β-glucuronidase. At the same time the lysosome became less fragile and their density distribution underwent a progressive broadening in the direction of decreasing density, extending to a value as low as 1.03. Incipient changes in lysosome density could be detected already in the early stages of the cholesterol-induced atheromatous transformation and in animals with moderate atheroma induced by a diet rich in saturated fatty acids. The cholesterol content of the cells increased up to 16-fold and the distribution of this substance was altered from a plasma membrane type in normal smooth muscle cells to one resembling that of lysosomal enzymes in foamy cells. Most likely, cholesterol storage is responsible for the decrease in lysosome density, and cholesterol-containing vacuoles in foamy cells are of lysosomal nature. Much of this cholesterol was in esterified form. In other experiments, no age- or sex-related changes in the aortic cell organelles could be demonstrated. After repeated intravenous injection of Triton WR-1339 there was a significant decrease in equilibrium density of the lysosomes indicating uptake of the detergent by this organelle. No change was observed after repeated injection of dextrans of various molecular weight, injection of neutral red, or starvation.

EFFECTS OF HIGH LEVELS OF DIETARY COPPER ON ENDOGENOUS LIPID METABOLISM IN THE PIG

Two experiments were carried out to study the effects of dietary copper on the performance and lipid metabolism of pigs. In experiment 1 the addition of 250 ppm copper had no significant effect on performance but resulted in a more unsaturated depot fat. It was postulated that the latter effect could be caused by a preferential mobilization of saturated fatty acid (SFA) from adipose tissue, but examination of the fasting free fatty acid (FFA) plasma fraction revealed no evidence for any preferential mobilization, although the concentration of total FFA was increased in the copper-fed animals. The objective of experiment 2 was to investigate whether dietary copper resulted in an increased synthesis of unsaturated fatty acids (UFA) in adipose tissue. Uptake of plasma triglycerides was prevented by prior injection of Triton WR-1339 to give an uncomplicated picture of fatty acid synthesis. The results showed that copper did alter the distribution of14C activity in adipose tissue fatty acids but shifted the pattern to one of a more saturated nature, which clearly invalidated the hypothesis that copper increases synthesis of UFA.

Catalase particles in the epithelial cells of the guinea-pig small intestine.

Purified preparations of epithelial cells have been made from the guinea-pig small intestine. Homogenates of these preparations have been analysed by centrifugation in a zonal rotor. The results confirm the presence of lysosomes in these cells and indicate the existence of catalase particles which equilibrate in a sucrose gradient at a density of between 1.21 and 1.23 and which have a different distribution from other subcellular particles except lysosomes. Injection of Triton WR-1339 into fasting animals enables the separation of lysosomes and catalase particles.

Lysosomes in rat-kidney tissue

Summary 1. The intracellular distribution of catalase and several acid hydrolases has been investigated on homogenates of rat kidney and compared with those of cytochrome oxidase (EC 1.9.3.1), glutamic dehydrogenase (EC 1.4.1.2) and glucose-6-phosphatase (EC 3.1.3.9), used as reference enzymes for mitochondria and microsomes. 2. Acid hydrolases and catalase are principally associated with fractions sedimenting at low centrifugal forces, but they also show significant activities in the soluble fraction. Their distribution patterns are quite different from those of cytochrome oxidase, glutamic dehydrogenase and glucose-6-phosphatase. 3. Distribution curves of acid hydrolases, catalase (EC 1.11.1.6) and two mitochondrial enzymes, cytochrome oxidase and glutamic dehydrogenase, have been determined after density equilibration in a sucrose gradient of a total mitochondrial fraction. Acid hydrolases show flattened distribution curves in contrast to the remarkably homogeneous distribution of mitochondrial enzymes. Catalase is found in the higher density regions of the gradient. 4. The possible role of these two enzymes in insect flight metabolism is discussed. 5. Acid hydrolases and catalase show the phenomenon of structure-linked latency but hypotonic treatment does not greatly change the activity of the latter enzyme. 6. The injection of Triton WR1339, which lowers the density equilibration of lysosomal enzymes in the liver, has a similar effect on kidney acid hydrolases. However, the action of this substance is not so marked as for the liver enzymes. Catalase and glutamic dehydrogenase do not seem to be affected by this treatment. 7. These results are discussed with respect to the presence of lysosomes in the rat kidney and to their properties.

Acceleration of hepatic cholesterol synthesis by triton WR-1339.

Synthesis of cholesterol from acetate in the rat was studied after injection of triton WR-1339, both in the whole animal and by the liver slice technique. Synthesis appeared to be increased 3-fold 24 hours after the injection. It was depressed after 72 hours, concurrently with a rise in the cholesterol concentration in the liver and its fall towards normal in the blood. When triton was injected into cholesterol-fed animals, or when their bile ducts were ligated, cholesterol synthesis was faster than in the untreated, normally fed controls, despite, in some instances, an elevated concentration of cholesterol in the liver.

The mechanism responsible for the hypercholesteremia induced by triton WR-1339.

Injection of triton WR-1339 into rats leads to a rapid increase in the cholesterol, cholate, and various lipid fractions of their blood. The increase in cholesterol is confined to the blood itself. The cholesteremic effect of triton was not dependent upon a prior accumulation of cholate in plasma. The liver was found to be the source of the excess cholesterol but the rate of cholesterol synthesis, the excretion of cholate, and the cholesterol content of the liver were not changed by injection of triton. The cholesteremic effect of triton is not due to alteration in the intestinal excretion of cholesterol. Transfer of blood between "tritonized" and normal rats leads to a disappearance of the hypercholesteremia in the former and its appearance in the latter animals. The plasma proteins of rats injected with triton are markedly changed qualitatively. Heparin was found to inhibit the hypercholesteremic effect of triton. The hypercholesteremia following triton injection appears to be due to a fundamental physicochemical change in the plasma proteins produced by injection of this detergent.