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Query: UMLS:C0004153 (atherosclerosis)
 77,401 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isolation of non-esterified [14C]cholesterol bound to albumin from rat serum, 8 days after i.p. injection of [14C]cholesterol, was achieved by affinity chromatography, using Cibacron blue F3GA bound to Sepharose 4B and by Sephadex G-150 column chromatography. Both methods permit isolation of large quantities of cholesterol-loaded albumin, free of globulins and lipoproteins. The isolated albumin-cholesterol fraction was estimated to be 4.6 mg/100 ml serum, which represents approx. the 24% of the non-esterified cholesterol present in the rat serum. Albumin-cholesterol, cholesterol glucoside, cholesterol hemisuccinate and hydroxylated derivatives of cholesterol produced a biphasic curve of changes in synaptosomal plasma membranes (SPM)-bound (Na+ + K+)-stimulated ATPase activity. Low concentrations of the ligand progressively increased the enzyme activity, while increasing the ligand concentration above that which maximally stimulated the enzyme activity, produced a progressive inhibition. Lipoproteins did not have any effect on the enzyme activity. The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene-labeled SPM, increased in albumin-cholesterol derivatives-treated SPM, which is consistent with a general decrease in membrane bilayer fluidity. The results provide evidence that the 'albumin-cholesterol' fraction of the serum may directly affect the cell membrane-bound enzyme activity.
Atherosclerosis 1986 Jul
PMID:Evidence for the existence of non-esterified cholesterol carried by albumin in rat serum. 301 57

The interest evoked by the Broad Breasted White Turkey (BBWT) as an animal model for studying the cardiovascular damages produced by hypertension and catecholamines is mainly due to the fact that hypertension is spontaneous and tissue and circulating catecholamines, especially norepinephrine, are extremely high. In this paper we focused our attention on three characteristic pathophysiological features displayed by these animals which are strictly related, as well as in humans, to the elevated blood pressure values and to catecholamine action. We also described the possibility of modifying the development of some of these lesions with pharmacological interventions liable to antagonize the peripheral effects of norepinephrine and epinephrine. The dissecting aneurysm of the aorta accounts for 5-10% of sudden deaths in this animal strain. It can be prevented by lowering blood pressure, especially with beta-blockers, and facilitated by MAO-inhibitors. The degree of cardiac hypertrophy is remarkably high and unexpectedly characterized by the synthesis of a "fast" V1-like isomyosin with high Ca++ activated ATPase activity, oxygen consumption and speed of muscle shortening. Neither the reduction of the degree of cardiac hypertrophy, nor treatment with labetalol alone were able to modify this peculiar pattern. In spite of having very high levels of high-density-lipoproteins, which are known to be protective against atherosclerosis, this animal develops a severe atheromatous disease especially in the abdominal aorta, where the cellular growth has also been proven to be in vitro more pronounced than in the thoracic tract. Treatment with beta-blockers reduced the severity and extent of the lesion even in absence of a significant reduction in blood pressure.
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PMID:Catecholamine-induced cardiovascular disease in the spontaneously hypertensive and atherosclerotic turkey. 304 59

The effect on the cardiac sarcoplasmic reticulum of an atherogenic (1% cholesterol) diet fed during the neonatal vs the juvenile period of life was studied in Yorkshire swine. Male piglets were randomly assigned at birth to 1 of 4 groups: group I (control), group II (lactation feeding), group III (juvenile period feeding) and group IV (lactation and juvenile feeding). All animals were killed at 55 weeks of age and cardiac sarcoplasmic reticulum (SR) isolated for assay of calcium uptake, Ca2+-Mg2+ ATPase activity, and lipid analysis by thin-layer chromatography and gas chromatography. The amount of cholesterol/mg SR protein and the cholesterol/phospholipid ratio were higher in the animals fed during lactation (groups II and IV) and lower in those fed only during the juvenile period (group III). Phospholipid fatty acid patterns as measured by gas chromatography were unaltered in any group. Calcium uptake was markedly diminished in all experimental conditions: group II 47%, group III 65% and group IV 96%. Compared to the observed changes in calcium transport, the ATP hydrolytic activity was relatively less affected. Only in group IV a significant decrease (41%) was seen. Groups II and III show no change in ATP hydrolytic activity. The decrease in calcium uptake and altered cholesterol/phospholipid ratio without effect on ATP hydrolytic activity is consistent with an uncoupling of calcium transport related to the atherogenic diet in early life.
Atherosclerosis 1985 Apr
PMID:Cardiac sarcoplasmic reticulum. Effects of an atherogenic diet during the neonatal and juvenile period. 315 93

The biochemical and functional changes associated with ligation (40 min) of the left circumflex coronary artery and subsequent reperfusion (60 min) in the rabbit made diabetic with alloxan were studied and compared with those of control animals. Measurement of haemodynamic parameters revealed that both left ventricular pressure and mean arterial pressure were significantly (P less than 0.05) decreased after ligation and reperfusion in the diabetic animals compared with controls. Analysis of subcellular organelle enzyme markers from the ischaemic tissue revealed that sarcolemmal Na+,K+-ATPase, mitochondrial ATPase and sarcoplasmic reticulum ATPase activities were decreased after ligation to the same extent in the diabetic and control animals. However, upon reperfusion, the recovery of mitochondrial ATPase activity was significantly (P less than 0.05) less in the diabetic animals than in the controls. Ion measurements revealed a significant (P less than 0.05) depletion of Mg in diabetic hearts before ligation, and this was augmented during reperfusion. In contrast, a significantly (P less than 0.05) higher calcium accumulation was observed upon reperfusion in the hearts of diabetic animals. Similarly, both tissue ATP levels and the ability of the mitochondria to generate ATP were depressed to a greater degree in the diabetic animals. Our results indicate, therefore, a greater susceptibility of the diabetic myocardium to ischaemic/reperfusion injury which in the clinical situation would exacerbate the problems associated with atherosclerosis and possibly contribute to the high mortality from cardiovascular complications in diabetic patients.
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PMID:Coronary artery ligation and reperfusion in rabbits made diabetic with alloxan. 381 32

In order to study the influence of the cholesterol content on the calcium entry channel, the human red blood cell was used as a model system. The cholesterol to lecithin ratio (C/L ratio) of the membrane was modified experimentally by incubating the cells (15h, 25 degrees) with liposomes of defined C/L ratios. Subsequently, net 45Calcium-influx into the cell was measured by inhibiting the Ca-ejecting ATPase with vanadate. Additionally, the use of nitrendipine, a potent calcium channel inhibitor, during incubation allowed the determination of Ca-influx through the calcium channel. A positive correlation between the 45Ca++-influx and the molar C/L ratio of the membrane was found over a wide C/L range. A molar C/L ratio of 1.4 in the membrane increased calcium influx by 150 % compared to controls (molar C/L ratio = 0.8, calcium influx rate = 100 %), while a molar C/L ratio at less than 0.75 decreased calcium influx by 50 %. We conclude, that the cholesterol content of the membrane greatly influences the calcium channel and thus plays a pivotal role for the availability of calcium as a second messenger. These findings may provide a link between high plasma cholesterol and the development of atherosclerosis as well as enhanced platelet aggregability.
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PMID:The cholesterol content of the human erythrocyte influences calcium influx through the channel. 609 23

Diabetes mellitus causes congestive heart failure in humans, independent of atherosclerosis. The present study extends previous work on the reversibility, with insulin, of the alterations in myocardial function and contractile protein biochemistry observed in diabetic rats. The response of these alterations to different fixed doses of insulin was explored. Diabetic rats were given 0, 0.5, 1, 1.5, 2, or 2.5 U of insulin daily for 6 wk. Papillary muscle function, actomyosin ATPase, and myosin isoenzyme distribution showed progressive normalization with increasing insulin dose as blood glucose concentration returned to normal. Thus insulin therapy in diabetic rats on a normal diet produces continuous improvement in cardiac function and biochemistry as euglycemia is approached. This study also suggests that mild diabetes results in qualitatively identical, although quantitatively less pronounced, myocardial changes compared with those observed in severely diabetic rats.
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PMID:Diabetic cardiomyopathy in rats: mechanical and biochemical response to different insulin doses. 623 41

Structural and functional characteristics of erythrocyte membranes were studied in rabbits with experimental atherosclerosis. In animals with single lipid spots in the aorta, a significant rise of the plasma cholesterol level was associated with the increased cholesterol/phospholipid (CS/PL) ratio and diminished activity of erythrocyte membrane Na+, K+-ATPase. EPMR spin probe data point to changes in structural membrane characteristics--an increase in order parameter for fatty acid chains of lipids and expansion of the temperature interval of the transition phase in the membranes. In rabbits with total aorta injury, a further increase both in the plasma cholesterol concentration and in the CS/PL ratio as well as in structural changes in erythrocyte membranes does not lead to another decrease in the enzymatic activity. In aorta homogenates of the experimental animals, the activity of Na+, K+-ATPase correlated with that in the erythrocyte membrane. This suggests the existence of similar chemical and structural changes in aorta cell membranes. The data may provide an indirect evidence in favour of the hypothesis of the involvement of smooth muscle cells and membrane enzymatic activity alterations in atherosclerosis.
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PMID:[Structural and functional changes in erythrocyte membranes in experimental atherosclerosis]. 624 22

Activity of Na+, K+-ATPase and the molar ratio "cholesterol/phospholipids" were estimated in erythrocyte membranes of patients with ischemic heart disease, in which an impairment of coronary arteries was documented by means of angiography. Distinct inhibition of the enzymatic activity as well as an increase in the ratio "cholesterol/phospholipids" was observed in erythrocyte membranes of all the patients; the alteration of these parameters was maximal in the patients with IIa and IIb forms of hyperlipoproteinemia. Reverse correlation (r = -0.604) was found between the enzymatic activity in erythrocyte membranes and the "atherogeneity coefficient" in blood plasma lipoproteins. The data obtained suggest that blood plasma lipoproteins are responsible for regulation of cholesterol content in cell membranes and, according to the membrane hypothesis of atherogenesis, this phenomenon is important in development of atherosclerosis.
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PMID:[Na+, K+-ATPase activity and cholesterol content in erythrocyte membranes of patients with coronary atherosclerosis in various forms of dyslipoproteinemia]. 631 64

The object of this study was to examine changes in plasma membranes of arterial smooth muscle (ASM) during atherogenesis obtained from cholesterol-fed (2%) rabbits. A microsomal fraction highly enriched with plasma membrane markers was prepared by subcellular organelle fractionation from ASM freshly isolated from the thoracic aorta. The membranes were analyzed for unesterified (free) cholesterol (FC) content, membrane bilayer structural parameters (X-ray diffraction), phospholipid (PL) composition, and Na+/K(+)-ATPase activity and kinetics. Following 8 weeks on diet, membrane FC content increased 67.1%. Small angle X-ray diffraction demonstrated an increase in membrane hydrocarbon core electron density and an increase in overall lipid bilayer width (56-62 A). This increase in bilayer width was highly correlated with the membrane FC content (r = 0.992). Both membrane FC content And bilayer width independently correlated with time on cholesterol diet. The phospholipid profile of the membrane revealed a 16.4% increase in phosphatidylcholine (PC), 19.3% decrease in phosphatidylethanolamine (PE) and 62.8% increase in sphingomyelin (SM) content with no change in total PL content. Na+/K(+)-ATPase activity was decreased 52.2% (P < 0.005), and [3H]ouabain binding kinetics demonstrated a 27.6% decrease in maximum binding sites (Bmax) (P < 0.01) while the dissociation constant (Kd) remained unaltered. Membranes obtained from control ASM cells enriched with FC in culture demonstrated changes similar to those in atherosclerotic ASM membranes including an increase in membrane FC content, an increase in bilayer width, and a decrease in Na+/K(+)-ATPase activity with decreased ouabain Bmax. These data demonstrate marked compositional, structural and functional changes in ASM cell membrane characteristics in dietary atherosclerosis. These changes were highly correlated with cholesterol accumulation in the plasma membrane bilayer and were observed before the appearance of visible lesions. We suggest that these membrane defects may be linked with early atherogenesis.
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PMID:Atherosclerosis alters the composition, structure and function of arterial smooth muscle cell plasma membranes. 754 33

The activities of protein kinase C, total, Mg2 and Na+, K(+)-dependent ATPases in red cell membranes were compared in 46 patients with insulin independent, 30 ones with insulin dependent diabetes mellitus with various degrees of vascular disorders, and in 17 patients with atherosclerosis with the predominant involvement of the main vessels of the lower limbs. Diabetes mellitus and the progress of vascular disorders were associated with a more marked depression of protein kinase C, total and Na+, K(+)-dependent ATPase activities, this being particularly characteristic of the patients with insulin-independent diabetes and macrovascular disorders. Inhibited activities of protein kinase C and ATPases in red cell membranes in the course of diabetic vascular disorders progress evidence their contribution to the pathogenesis of diabetic angiopathy.
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PMID:[Activity of membrane-bound protein kinase C and ATPase in erythrocytes in diabetic angiopathy]. 805 53


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