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1.
Total lipoproteins as well as fractionated VLDL+LDL and HDL from fasted control rats and bileligated rats were tested in liver
perfusion for their effect on 3-hydroxy-3-methylglutaryl CoA reductase to increase 3-hydroxy-3-methylglutaryl CoA reductase
activity than that of the control total lipoproteins. When the fractionated lipoproteins were tested from fasted control rats,
it was found that the major stimulating activity was in the HDL fraction with minor activity in the VLDL+LDL fraction. When
these plasma components isolated from fasted bile-ligated rats were tested, it was found that the major activity had shifted
to the VLDL+LDL fraction with the HDL having only a minor stimulatory role. The possible mechanism of action of the abnormal
lipoproteins associated with bile obstruction in regulating 3-hydroxy-3-methylglutaryl CoA reductase activity is discussed. 相似文献
2.
l-Carnitine plays an important role in the mitochondrial uptake of long-chain fatty acids in mammals. It has recently been
shown that this compound has a marked hypo-cholesterolemic effect when used in conjunction with lipid-rich diets. The aim
of this study was to investigate the effects of l-carnitine on the fatty acid composition of plasma lipoproteins in rabbits fed with different diets. Four different groups
were investigated: group I (standard diet), group II (standard diet supplemented with l-carnitine at 80 mg/kg), group III (standard diet supplemented with 0.5% cholesterol), and group IV (standard diet supplemented
with 0.5% cholesterol plus l-carnitine at 80 mg/kg). The feeding period was 126 d. Total plasma cholesterol was indistinguishable in groups I and II,
but increased nearly 40-fold in group III. This increment was reduced by 50% in group IV. Correspondingly, total cholesterol
content in lipoprotein fractions [very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein
(HDL) separated by agarose gel chromatography was the same for groups I and II, while for animals fed a cholesterol-rich diet
(III) total cholesterol in VLDL+LDL increased nearly 100-fold when compared with groups I and II but, again, the increment
was reduced by 50% in group IV. In contrast, total cholesterol in HDL increased only fivefold for both groups III and IV when
compared with groups I and II, indicating no effects of l-carnitine on this parameter. The reduction of total cholesterol in VLDL+LDL particles in animals fed a cholesterol-rich diet
plus l-carnitine was associated with a marked decrease in the ratio of cholesteryl ester to free cholesterol and a dramatic increase
in their phospholipid content; opposite effects were observed for HDL. l-Carnitine induced a marked decrease in the saturated to unsaturated C16+C18 fatty acid ratio in cholesteryl esters associated with VLDL and LDL from animals fed with both normal and cholesterol-rich
diets. The opposite effect (a large increase in the saturated to unsaturated fatty acid ratio) was observed for both cholesteryl
esters and phospholipids associated with HDL in animals fed with both diets. The results suggested that the hypocholesterolemic
effects of l-carnitine could be associated with increased systemic breakdown of cholesteryl esters, a probable increase in reverse cholesterol
transport, and the stabilization of a phospholipid-based structure of VLDL+LDL particles. 相似文献
3.
Dietary n-3 fatty acids, abundant in fish oil, exert a variety of effects that attenuate cardiovascular disease. In this study,
we assessed the effect of fish oil (menhaden oil) on the serum lipid profile in hypertensive and normotensive rats. Spontaneously
hypertensive rats (SHR) or Sprague-Dawley rats (SD) were fed either standard powdered diet (L-485), or L-485+5% menhaden oil
(MO) or L-485+5% corn oil (CO) from weaning through eight months of age. Systolic blood pressure (BP) was periodically determined
on SHR. Serum lipid profiles were performed at eight months on sample taken from the exposed hearts of anesthetized, fasted
rats. SHR, compared with SD (diets combined) had significantly lower triaclyglycerols (TG), higher cholesterol (CHOL), higher
high density lipoprotein cholesterol (HDL CHOL), higher low density lipoprotein cholesterol (LDL CHOL), and a higher LDL:HDL
ratio. Comparison among diets (strains combined) revealed that rats fed MO had the lowest values for TG, CHOL, LDL and LDL:HDL;
HDL did no vary with diet. SHR were less responsive to diet-induced changes than were SD; no decrease in TG, LDL or LDL:HDL
was observed in SHR, nor was degree of hypertension altered in SHR by the MO or CO diet. In summary, MO is more effective
than CO in shifting the lipid profile of rats toward one that is less atherogenic. However, the SD rat is more susceptible
to diet-induced lipid modification than is the SHR. 相似文献
4.
High performance liquid chromatography with gel exclusion columns was used for quantitative measurement of plasma lipoproteins.
A combination of columns TKS 4000 PW and 3000 PW gave good separation of very low (VLDL), low (LDL) and high (HDL) density
lipoproteins. The area under each lipoprotein peak detected by absorbance at 280 nm was measured by digitizing and was expressed
as cm2. Purified lipoprotein standards isolated by ultracentrifugation were also chromatographed in increasing concentrations. The
area under the lipoprotein standard peak was linearly related to the amount of total protein over a wide range. The areas
of most of the measured plasma lipoproteins were within the linear range. The relationship between the area and the amount
of protein for each standard was used to quantitate the amount of protein and was expressed as mg/dl plasma. This technique
is simple and requires a small amount of plasma. The validated technique was applied to a large population of pedigreed baboons.
An average plasma lipoprotein profile of feral baboons on the chow diet was characterized by a high level of HDL (90.9±30.7
mg/dl) with a lesser amount of LDL (29.1±13.2 mg/dl). VLDL was present in much lower concentration (8.6±2.6 mg/dl). Feeding
a high cholesterol and high saturated fat (HCHF) diet raised both LDL (1.5-fold) and HDL levels (1.3-fold) without changing
VLDL levels. Progeny of sires with low response to dietary cholesterol increased their HDL protein when challenged with HCHF
diet without any change in their LDL or VLDL. Progeny of high-responding sires, however, had increases in both their HDL and
LDL levels when challenged with HCHF diet. The survey of lipoprotein profiles of the pedigreed baboon colony disclosed a number
of animals with interesting and unusual lipoprotein patterns. 相似文献
5.
This experiment was designed to evaluate the effects of dietary red wine phenolic compounds (WP) and cholesterol on lipid
oxidation and transport in rats. For 5 wk, weanling rats were fed polyunsaturated fat diets (n−6/n−3=6.4) supplemented or
not supplemented with either 3 g/kg diet of cholesterol, 5 g/kg diet of WP, or both. The concentrations of triacylglycerols
(TAG, P<0.01) and cholesterol (P<0.0002) were reduced in fasting plasma of rats fed cholesterol despite the cholesterol enrichment of very low density lipoprotein
+ low density lipoprotein (VLDL+LDL). The response was due to the much lower plasma concentration of high density lipoprotein
(HDL) (−35%, P<0.0001). In contrast, TAG and cholesteryl ester (CE) accumulated in liver (+120 and +450%, respectively, P<0.0001). However, the cholesterol content of liver microsomes was not affected. Dietary cholesterol altered the distribution
of fatty acids mainly by reducing the ratio of arachidonic acid to linoleic acid (P<0.0001) in plasma VLDL+LDL (−35%) and HDL (−42%) and in liver TAG (−42%), CE (−78%), and phospholipids (−28%). Dietary WP
had little or no effect on these variables. On the other hand, dietary cholesterol lowered the α-tocopherol concentration
in VLDL+LDL (−40%, P<0.003) and in microsomes (−60%, P<0.0001). In contrast, dietary WP increased the concentration in microsomes (+21%, P<0.0001), but had no effect on the concentration in VLDL+LDL. Cholesterol feeding decreased (P<0.006) whereas WP feeding increased (P<0.0001) the resistance of VLDL+LDL to copper-induced oxidation. The production of conjugated dienes after 25 h of oxidation
ranged between 650 (WP without cholesterol) and 2,560 (cholesterol without WP) μmol/g VLDL+LDL protein. These findings show
that dietary WP were absorbed at sufficient levels to contribute to the protection of polyunsaturated fatty acids in plasma
and membranes. They could also reduce the consumption of α-tocopherol and endogenous antioxidants. The responses suggest that,
in humans, these substances may be beneficial by reducing the deleterious effects of a dietary overload of cholesterol. 相似文献
6.
Pe¯teris Alberts Gunnel Klingstrm Vibeke Arrhenius‐Nyberg Catarina Larsson Kjell S. Sakariassen 《European Journal of Lipid Science and Technology》2006,108(6):453-458
The aim of the present study was to assess cholesterol‐containing lipoprotein profiles in minute serum samples. The lipoprotein profiles of KKAy and transgenic KKAy‐CETP mice and of other species were determined. The transgenic KKAy‐CETP mice express the simian enzyme cholesteryl ester transfer protein (CETP). The serum profile of the cholesterol‐containing high‐density (HDL), low‐density (LDL) and very‐low‐density lipoproteins (VLDL) was monitored on a Superose 6 column using fast protein liquid chromatography. Serum from several mouse and rat strains, rabbit, hamster, pig and man was included for comparative and method validation purposes. The chromatograms showed that the transgenic KKAy‐CETP mice had significantly decreased relative levels of HDL vs. VLDL and LDL cholesterol (p <0.001). Introduction of the CETP gene shifted the serum profile of the cholesterol‐containing lipoproteins of the KKAy‐CETP mice closer to the human profile in a dose‐dependent manner, thus making these mice an interesting model for man. The described lipoprotein separation technology offers promising and reliable opportunities for studies of blood lipoprotein profiles with minute serum samples, in both animals and man. 相似文献
7.
Nocturnal intragastric feeding has been shown to be an effective means to improve clinical and biochemical features in glycogen
storage disease type I (GSD-I). In this study, we investigated the fatty acid patterns in a whole plasma and in circulating
lipoproteins in patients on this therapy. The results demonstrated massive concentration of total fatty acids coupled with
higher levels of triglycerides, free cholesterol, cholesterol ester and phospholipids. This hyperlipidemia involved all fatty
acids without distinction of carbon or bond numbers. However, the increase was more pronounced for saturated than polyunsaturated
fatty acids, as was demonstrated by the ratios of both oleic acid to linoleic acid (1.91±0.40 vs 0.80±0.09 in controls) and
of ω3+ω6 to ω9 fatty acid families (0.92±0.11 vs 1.66±0.08 in controls). The fatty acid patterns in very low (VLDL), low (LDL)
and high (HDL) density lipoprotein showed substantial differences in composition, reflecting an association between an abnormal
lipoprotein pattern and essential fatty acid deficiency. Furthermore, GSD-I patients exhibited a significant increase in VLDL
(17±2 vs 47±7 mg/dl) and LDL cholesterol (124±7 vs 206±24 mg/dl), coupled with a decrease in HDL cholesterol (49±4 vs 28±3
mg/dl). These data documenting high LDL cholesterol and low HDL cholesterol associated with an increased concentration and
proportion of saturated fatty acids suggest that GSD-I patients on nocturnal intragastric feeding are at high risk for atherosclerosis
and its complications. 相似文献
8.
Serum cholesterol precursor sterols reflect the activity of cholesterol synthesis. In this study, squalene, methyl sterol
and lathosterol contents were studied in very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density
lipoprotein (HDL) of heterozygous familial hypercholesterolemia patients without and with ileal bypass. The contents of lathosterol
and all methyl sterols (lanosterol, Δ8,24-dimethylsterol, Δ8-dimetylsterol, Δ8-methostenol and methostenol), but not of squalene were increased in all lipoproteins by ileal bypass. The increase in the
free methyl sterols was more marked than that in the esterified ones. The percentage esterification of the methyl sterols
was highest in HDL and lowest in VLDL. Lipoprotein methyl sterol contents were positively correlated with each other and with
cholesterol synthesis. The methyl sterols were slightly concentrated in LDL, and squalene strongly concentrated in VLDL. It
is concluded that long-term stimulation of cholesterol synthesis increases the methyl sterols in all lipoproteins. 相似文献
9.
In this study, we evaluated on a comparative basis the dietary effect between eicosapentaenoic acid (C20:5, EPA)- containing soyphospholipid and soyphospholipid without EPA when added at 5% or 10% level by weight in soybean oil as the dietary oil on the proportions of lipid components in serum of rats. Rats were taken in five groups. One group was fed 20% soybean oil. Two groups received soybean oil containing 5% and 10% soyphospholipid by weight, respectively. Two other groups were fed soybean oil containing 5% and 10% EPA- containing soyphospholipid by weight, respectively. The other dietary components remained same for all the groups. The feeding experiment was conducted for 4 weeks. After the feeding period there was no significant change in weight gain, food intake and food efficiency ratio (FER). No significant change was observed in serum lipid profiles between the rats fed soybean oil and soybean oil with 5% or 10% soyphospholipid. There was significant decrease in serum triglyceride (TG) level in the rats fed soybean oil blended with EPA containing soyphospholipid at 5% level. The contents of total cholesterol (TC), TG, very low density lipoprotein (VLDL)-cholesterol and low density lipoprotein (LDL)-cholesterol decreased significantly while high density lipoprotein (HDL)-cholesterol increased compared to the soyphospholipid group at 10% level. 相似文献
10.
While it is known that the transfer of cholesteryl ester (CE) from high density lipoprotein (HDL) to the apo B-containing
lipoproteins is increased in patients with diabetes, the extent to which the various lipoprotein fractions engage in neutral
lipid exchange and the magnitude to which triglyceride (TG) is translocated is not known. To examine in greater detail neutral
lipid net mass transfer in diabetes, the HDL subfractions and the apo B-containing lipoproteins were separated, and the net
mass transfer of CE and TG was compared to that of control subjects. In both groups, bidirectional transfer of CE from HDL3 to very low density lipoprotein (VLDL) + low density lipoprotein (LDL) and of TG from VLDL+LDL to HDL3, took place, but this process was significantly greater (P<.01) in insulin-dependent diabetes mellitus (IDDM). In contrast, CE and TG accumulated in HDL2 to a similar degree in normal and IDDM subjects. In recombination experiments with each of the apo B-containing lipoproteins,
IDDM VLDL had a greater capacity to facilitate the exchange of core lipids from both IDDM and control HDL3: on the other hand, LDL from IDDM and control subjects both donated TG and CE to HDL2 and affected little change in HDL3. These findings indicate that all the major plasma fractions normally participate in the trafficking of CE and TG among the
lipoproteins during neutral lipid transfer and show that the principal perturbation in cholesteryl ester transfer in IDDM
involves altered interaction between VLDL and the HDL3 subfraction. 相似文献
11.
Tomohisa Nagano Nobuyoshi Seki Yoichi Tomita Tomonori Sugita Yuta Aida Munenori Itagaki Satoshi Sutoh Hiroshi Abe Akihito Tsubota Yoshio Aizawa 《International journal of molecular sciences》2015,16(9):20576-20594
Reduced low-density lipoprotein (LDL) cholesterol level is a characteristic feature of dyslipidemia in chronic hepatitis C virus (HCV) infection. However, abnormality in serum triglyceride (TG) has not been fully investigated. To clarify the impact of HCV genotype 1b (G1b) infection and advanced fibrosis on serum TG profiles, TG concentrations in lipoprotein fractions were examined in fasting sera from 185 subjects with active or cleared HCV infection by high-performance liquid chromatography. Serum lipoproteins were fractionated into four classes: chylomicron, very low-density lipoprotein (VLDL), LDL, and high-density lipoprotein (HDL). Then, the significance of HCV G1b infection on TG levels in each lipoprotein fraction was determined using multiple regression models. We found that active HCV G1b infection was positively associated with high HDL-TG levels and low VLDL-TG levels, independent of other factors included in the regression model. In VLDL sub-fractions, active HCV infection was only found to be associated with low levels of large VLDL-TG. Similarly, advanced liver fibrosis in chronic HCV G1b infection was associated with high levels of LDL-TG, HDL-TG, and small VLDL-TG, independent of other clinical factors. These findings indicate that active HCV G1b infection and advanced fibrosis are closely associated with abnormal serum TG profiles. 相似文献
12.
Human serum lipoproteins containing B-protein have been isolated using an immunoadsorber. Bromoacetyl cellulose was combined
with pure antibodies to low density lipoprotein (LDL) and an immunoadsorber of high capacity was obtained. With 1 g of this
immunoadsorber all LDL and very low density lipoprotein (VLDL) from 30 ml pooled human serum were adsorbed and then eluted
with glycine-HCl buffer pH 3.2 at 0 C. The isolated lipoproteins were investigated by electrophoresis, immunodiffusion and
ultracentrifugation, and found to be identical to LDL+VLDL isolated by ultracentrifugation. 相似文献
13.
The influence of dietary restriction on cholesterol transport and metabolism was investigated in rabbits given standard or
cholesterol-rich diets (0.2 g cholesterol/kg body weight daily) eitherad libitum or with 50% caloric ration. Dietary restriction which has only a slight influence in control rabbits markedly aggravated
the disturbances induced by exogenous cholesterol. With limited feeding, control rabbits presented a moderate increase in
plasma cholesterol, whereas marked aggravation of hypercholesterolemia was observed in cholesterol-fed rabbits. Analysis of
the lipoprotein profile showed that the excess of plasma cholesterol with the restricted cholesterol-rich diet corresponded
to an increase in the concentration of very low density lipoprotein (VLDL) and low density lipoproteins (LDL) without any
additional changes in the composition of these lipoproteins. No significant change appeared in the high density lipoprotein
(HDL) concentration. The parameters of cholesterol metabolism were determined, from the curves of [3H] cholesterol radioactivity decrease, using a two-pool model. The increase in cholesterol turnover rate induced by the cholesterol-rich
diet was accentuated by dietary restriction, whereas rabbits on standard restricted diet showed a slight decrease. The large
increase in the size of both pools A and B in cholesterol-fed rabbits was even more pronounced with limited feeding. Dietary
restriction induced additional accumulation of cholesterol in the aortic wall and the grade of the lesions was also aggravated. 相似文献
14.
Estradiol implants in chicks resulted in marked elevation of all major plasma lipids with greatest increase in triglyceride
(TG) followed by phospholipid (PL) and cholesterol (C). During the two-wk period, plasma TG level in estrogen (E)-treated
chicks increased to about 45 times that of controls (139.6 vs 6,368.3 mg/dl). The level of cholesterol also increased steadily
during the same period, attaining nearly a six-fold increase in comparison with the control (150.7 vs 871.8 mg/dl), and the
level of PL was markedly elevated from 209 to 2,861 mg/dl. Besides the induction of hyperlipidemia, E treatment also resulted
in a notable alteration in the fatty acid composition of plasma lipids; there was an increase in oleic acid concomitant with
a decrease in polyunsaturated fatty acids, particularly, linoleic acid. One day after implantation, the percentage of oleic
acid in TG fraction increased from 39.2 to 43.7%, reaching 55.4% of the total fatty acids at day 14. In contrast, the levels
of linoleic and arachidonic acid decreased significantly from 16.1 to 8.3% and 4.3 to 0.6%, respectively, during the same
period. In cholesteryl ester (CE) and PL, the oleic acid level also increased from 25.2 to 47.3% in the former and from 11.9
to 29.6% in the latter, reflecting enhanced hepatic lipogenesis. Analysis of plasma lipoproteins in E-treated chicks revealed
dramatic alterations in the concentrations of lipids and protein in individual lipoprotein fractions, especially very low
density lipoprotein (VLDL) fraction. The respective levels of TG, C and PL in the VLDL fractions were 10.0, 0.6 and 1.0 mg/dl
in the control, and 3,904.4, 530.3 and 1,365.2 mg/dl in chicks implanted with estrogen for seven days. The concentrations
of TG, C and PL also were markedly increased in the low density lipoprotein (LDL) fraction in these birds. However, the cholesterol
content of the high density lipoprotein (HDL) fraction was decreased dramatically in E-treated chicks (47.1) relative to the
control (121.5 mg/dl). The protein level in the VLDL fraction from E-treated chicks was profoundly elevated to a level 300-fold
greater than controls. TG secretion rates were measured in vivo following the administration of Triton WR-1339. In control
chicks, plasma TG secretion rate was 2.29 mg/min; whereas, chicks treated with E for one and three days showed significantly
higher TG secretion rates of 3.18 and 5.27 mg/min, respectively. TG removal rates were measured in vivo after administration
of a 10% fat emulsion. Although plasma TG concentrations were different between control and E-treated birds, no significant
differences were found in TG removal rates in those birds, indicating no impairment of TG clearance in E-treated chicks. 相似文献
15.
A series of short chain fatty acid derivatives of aminimides were shown to possess hypolipidemic activity in rats and mice.
Most of the agents tested lowered both serum cholesterol and triglyceride levels by at least 30% in mice and were effective
in hyperlipidemic induced mice. 1,1-Dimethyl-1-(2-hydroxypropyl)-amine mersitimide lowered serum cholesterol levels 41% and
serum triglyceride levels 56% at 20 mg/kg/day I.P. after 16 days. The same agent was active orally when administered to rats
with a 38% reduction in serum cholesterol and a 52% reduction in serum triglycerides after 14 days. The agents inhibited liver
acetyl CoA synthetase, ATP dependent citrate lyase and phosphatidate phosphohydrolase activities in vitro and in vivo. Reduction
of cholesterol, triglycerides, neutral lipids and phospholipid levels were noted in the livers of mice treated for 16 days.
In rat studies, cholesterol, triglyceride and phospholipid levels were reduced in liver, small intestine and the feces after
two weeks' dosing. The cholesterol content was reduced in the very low density lipoprotein (VLDL) and low density lipoprotein
(LDL) fractions but elevated in the high density lipoproteins (HDL). Triglyceride levels were lowered in the VLDL, and neutral
lipid levels were reduced in the chylomicron and VLDL fractions. 相似文献
16.
Elyett Gueux Christine Cubizolles Laurence Bussière Andrzej Mazur Yves Rayssiguier 《Lipids》1993,28(6):573-575
Hypertriglyceridemia observed in magnesium (Mg)-deficient rats was associated with a significant increase in the very low-density
lipoprotein (VLDL) plus low-density lipoprotein (LDL) fractions. The results fromin vitro copper-induced lipid peroxidation, expressed in terms of conjugated dienes and thiobarbituric acid reactive substances content,
showed that VLDL+LDL particles from Mg-deficient rats were more susceptible to oxidative damage than lipoproteins from control
rats. These results suggest that the mechanism responsible for the atherogenicity and tissue damage characteristic of Mg deficiency
may be mediated by an increased susceptibllity of triglyceride-rich lipoproteins to peroxidation in hypertriglyceridemic animals. 相似文献
17.
The hypocholesterolemic efficacy of various polyunsaturated fatty acids was compared in rats given cholesterol-enriched diets.
Capybara oil (CO, linoleic+α-linolenic acids), horse oil (HO, α-linolenic acid), and sardine oil (SO, eicosapentaenoic+docosahexaenoic
acids) were added to diets at 50 g/kg. The weight gain, food intake, and liver weight in the CO-fed group were significantly
higher than those in other groups during the 6-wk experimental period. The serum total and very low density lipoprotein (VLDL)+intermediate
density lipoprotein (IDL)+low density lipoprotein (LDL) cholesterol concentrations of the CO-fed and SO-fed groups were significantly
lower than in the HO-fed group after 6 wk. The serum high density lipoprotein cholesterol concentration in the SO-fed group
was significantly higher than that in the CO-fed and HO-fed groups. The fecal neutral sterol concentration in the CO-fed group
was reduced significantly compared with the other groups, and the fecal bile acid concentration in the HO-fed group was significantly
higher than that in the SO-fed group. The results of this study demonstrate that CO lowers the serum total cholesterol and
VLDL+IDL+LDL-cholesterol concentrations in the presence of excess cholesterol in the diet as well as SO. 相似文献
18.
Nicotine, a major component of cigarette smoke, plays an important role in the development of cardiovascular disease and lung
cancer in smokers. The effect of nicotine on lipoprotein metabolism was studied using rats as the experimental animal. There
was a significant increase in the total cholesterol, phospholipids, and triglycerides as well as the amount of lipids associated
with very low density lipoprotein (VLDL) and low density lipoprotein (LDL) in sera of nicotine-treated rats. The incorporation
of 3H labeled leucine into the apo B was found to be increased both in the medium and associated cells in the hepatocytes isolated
from nicotine-treated rats indicating an increased synthesis and secretion of the apo B containing lipoproteins. This was
further confirmed by the higher incorporation of 14C acetate into total and individual lipids of LDL and VLDL secreted into the medium as well as that associated with different
lipids in the cell layer. The activity of lipoprotein lipase in extrahepatic tissues and plasma lecithin cholesterol acyltransferase
activity were significantly lower in nicotine-treated rats. These results indicate that nicotine exerts hyperlipidemic effects
particularly by increasing the synthesis and secretion of triglyceride-rich lipoproteins. Since nicotine is one of the major
hazardous components present in cigarette smoke and tobacco, one can extrapolate that the deleterious effect exerted by nicotine
on rats extends to cigarette smokers and those who use other forms of tobacco. 相似文献
19.
Significant hypolipidemic activity was demonstrated by 6-ethoxycarbonyl-3-phenyl-1,3,5-triazabicyclo[3.1.0]hexane-2,4-dione,
2-ethoxycarbonyl-5-phenyl-1,3,5-triazine-4,6(1H,5H)-dione and 2-ethoxycarbonyl-5-(4-chlorophenyl)-1,3,5-trizine-4,6(1H,5H)-dione
in rodents at 20 mg/kg/day. These agents lowered serum cholesterol and triglyceride levels by approximately 40% in mice after
16 d. Tissue lipids in rat liver, small intestinal mucosa, aortic wall and feces were reduced by treatment with the agents.
Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol levels were reduced in the rat; high density
lipoprotein (HDL) cholesterol levels were elevated after 14 d of treatment. The activities of regulatory enzymes,e.g., acetyl-CoA synthetase, acyl-CoA:cholesterol acyltransferase, cholesterol 7α-hydroxylase,sn-glycerol-3-phosphate acyltransferase, phosphatidylate phosphohydrolase and heparin-induced lipoprotein lipase, involved inde novo synthesis of hepatic lipids were affected by the agents. The new compounds may represent another class of potentially useful
hypolipidemic agents for the treatment of atherosclerosis since HDL cholesterol levels were increased and VLDL and LDL cholesterol
levels were lowered by some of the agents. 相似文献
20.
Francisco J. Sanchez‐Muniz Sara Bastida 《European Journal of Lipid Science and Technology》2008,110(4):295-301
Reputable calculations such as the Friedewald formula are used extensively to determine LDL‐cholesterol (LDL‐C) values from known total cholesterol, triacylglycerol and HDL‐cholesterol (HDL‐C) levels. To the best of our knowledge, however, the validity of this equation has not yet been confirmed in rats. The aim of the present study is to give some insights as to why this formula must be used carefully in rats, and to find cut‐off points below which this formula can be considered reliable. Sera of 54 rats with different cholesterol, triacylglycerol and HDL‐C levels were tested. LDL was isolated by ultracentrifugation and LDL‐C measured by an enzymatic colorimetric method and compared against LDL‐C obtained by the formula. In rats whose serum cholesterol was <100 mg/dL, or whose HDL‐C constituted ≥75% of total cholesterol, or whose cholesterol/phospholipids ratio was <1, or whose serum did not contain β‐VLDL, LDL‐C obtained by both methods did not significantly differ. Under other conditions, however, and particularly in hypercholesterolaemic rats who did present β‐VLDL, the results clearly show that the Friedewald formula overestimates LDL‐C levels. In conclusion, (VLDL + LDL)‐C instead of VLDL‐C and LDL‐C must be used when ultracentrifugation or other alternative methods are not available to measure LDL‐C in hypercholesterolaemic rats. 相似文献