Serum lipids and apolipoproteins in patients with essential hypertension

Aqueous Humor Apolipoprotein Concentration and Severity of Diabetic Retinopathy in Type 2 Diabetes

An imbalance of plasma apolipoproteins has been linked to diabetic retinopathy (DR); however, there is scarce information regarding their presence in the aqueous humor (AH) and their role in DR. Here, we aimed at analysing the relationship between apolipoprotein concentrations in human AH and the severity of DR. Concentrations of apolipoproteins were measured retrospectively in patients with type 2 diabetes mellitus (T2DM) without DR (n = 23), with mild to moderate nonproliferative DR (NPDR) (n = 13), and advanced NPDR/proliferative DR (PDR) (n = 14) using a multiplex immunoassay. Compared to the non-apparent DR group, the concentrations of seven apolipoproteins were elevated in advanced NPDR/PDR (Apo AI 5.8-fold, Apo AII 4.5-fold, Apo CI 3.3-fold, Apo CIII 6.8-fold, Apo D 3.3-fold, Apo E 2.4-fold, and Apo H 6.6-fold). No significant differences were observed in apolipoprotein concentrations between patients with non-apparent DR and healthy controls (n = 17). In conclusion, the AH concentrations of apolipoproteins AI, AII, CI, CIII, D, E, and H increased in advancing stages of DR, suggesting their role in the pathogenesis of DR, which deserves further examination.

Experimental challenges regarding the in vitro investigation of the nanoparticle-biocorona in disease states

Toxicological evaluation of nanoparticles (NPs) requires the utilization of in vitro techniques due to their number and diverse properties. Cell culture systems are often lacking in their ability to perform comparative toxicity assessment due to dosimetry issues and capacity to simulate in vivo environments. Upon encountering a physiological environment, NPs become coated with biomolecules forming a biocorona (BC), influencing function, biodistribution, and toxicity. Disease-induced alterations in the biological milieu can alter BC formation. This study evaluates the role of low-density lipoprotein (LDL) in altering macrophage responses to iron oxide (Fe₃O₄) NPs. BCs were formed by incubating Fe₃O₄ NPs in serum-free media, or 10% fetal bovine serum with or without LDL present. Following exposures to a normalized dose (25 μg/mL), macrophage association of Fe₃O₄ NPs with a LDL-BC was enhanced. TNF-α mRNA expression and protein levels were differentially induced due to BCs. Cell surface expression of SR-B1 was reduced following all Fe₃O₄ NPs exposures, while only NPs with an LDL-BC enhanced mitochondrial membrane potential. These findings suggest that elevations in LDL may contribute to distinct BC formation thereby influencing NP-cellular interactions and response. Further, our study highlights challenges that may arise during the in vitro evaluation of disease-related variations in the NP-BC.

Effectiveness of blood pressure-lowering drug treatment by levels of absolute risk: post hoc analysis of the Australian National Blood Pressure Study

OBJECTIVES

In many current guidelines, blood pressure (BP)-lowering drug treatment for primary prevention of cardiovascular disease (CVD) is based on absolute risk. However, in clinical practice, therapeutic decisions are often based on BP levels alone. We sought to investigate which approach was superior by conducting a post hoc analysis of the Australian National Blood Pressure (ANBP) cohort, a seminal study establishing the efficacy of BP lowering in 'mild hypertensive' persons.

DESIGN

A post hoc subgroup analysis of the ANBP trial results by baseline absolute risk tertile.

SETTING AND PARTICIPANTS

3244 participants aged 35-69 years in a community-based randomised placebo controlled trial of blood pressure-lowering medication.

INTERVENTIONS

Chlorothiazide500 mg versus placebo.

PRIMARY OUTCOME MEASURES

All-cause mortality and non-fatal events (non-fatal CVD, congestive cardiac failure, renal failure, hypertensive retinopathy or encephalopathy).

RESULTS

Treatment effects were assessed by HR, absolute risk reduction and number needed to treat. Participants had an average 5-year CVD risk in the intermediate range (10.5±6.5) with moderately elevated BP (mean 159/103 mmHg) and were middle aged (52±8 years). In a subgroup analysis, the relative effects (HR) and absolute effects (absolute risk reduction and number needed to treat) did not statistically differ across the three risk groups except for the absolute benefit in all-cause mortality (p for heterogeneity=0.04). With respect to absolute benefit, drug treatment significantly reduced the number of events in the high-risk group regarding any event with a number needed to treat of 18 (10 to 64), death from any cause with 45 (25 to 196) and major CVD events with 23 (12 to 193).

CONCLUSION

Our analysis confirms that the benefit of treatment was substantial only in the high-risk tertile, reaffirming the rationale of treating elevated blood pressure in the setting of all risk factors rather than in isolation.

Effects of demographic, dietary and other lifestyle factors on the prevalence of hyperlipidemia in Guangxi Hei Yi Zhuang and Han populations

BACKGROUND

Han is the largest nationality and Zhuang is the largest minority among 56 nationalities in China. Hei Yi (means black-worship and black dressing) Zhuang is a special subgroup of 43 ethnic subgroups of Zhuang. There are limited data about the effect of environmental factors on the prevalence of hyperlipidemia in this population. The aim of this study was to determine the effects of demographic, dietary, and other lifestyle factors on the prevalence of hyperlipidemia in Hei Yi Zhuang and Han populations.

DESIGN

We performed a cross-sectional study of 1166 randomly selected people of Hei Yi Zhuang aged 7-84 years from seven villages in Napo County, Guangxi, China; and 1018 people of Han aged 6-89 years from nine villages in the same region.

METHODS

Information on demographic characteristics, dietary patterns, and other lifestyle factors was collected by standard questionnaires. Blood pressure, height, weight, waist circumference, serum lipids and apolipoproteins were measured, and body mass index (BMI) was calculated as a measure of weight relative to height.

RESULTS

The prevalence rates of hypercholesterolemia, hypertriglyceridemia and hyperlipidemia in Hei Yi Zhuang and Han were 23.6 versus 27.0% (P>0.05), 12.3 versus 14.4% (P>0.05) and 29.9 versus 34.2% (P<0.05), respectively. The prevalence of hyperlipidemia was positively correlated with age, BMI and blood pressure (P<0.05- 0.001) in Hei Yi Zhuang, whereas it was positively associated with age, BMI, blood pressure and alcohol consumption in Han (P<0.01-0.001). There was no significant correlation between the prevalence of hyperlipidemia and sex or cigarette smoking in Hei Yi Zhuang, Han or a combined population of Hei Yi Zhuang and Han (P>0.05), and alcohol consumption in Hei Yi Zhuang (P>0.05).

CONCLUSION

The current study reveals that there is a significant difference in the prevalence of hyperlipidemia and its risk factors between Hei Yi Zhuang and Han, which might result from different demographic characteristics, dietary habits and other lifestyle factors.

From the Cover: Disease-Induced Disparities in Formation of the Nanoparticle-Biocorona and the Toxicological Consequences

Nanoparticle (NP) association with macromolecules in a physiological environment forms a biocorona (BC), which alters NP distribution, activity, and toxicity. While BC formation is dependent on NP physicochemical properties, little information exists on the influence of the physiological environment. Obese individuals and those with cardiovascular disease exist with altered serum chemistry, which is expected to influence BC formation and NP toxicity. We hypothesize that a BC formed on NPs following incubation in hyperlipidemic serum will result in altered NP-BC protein content, cellular association, and toxicity compared to normal serum conditions. We utilized Fe3O4 NPs, which are being developed as MRI contrast and tumor targeting agents to test our hypothesis. We used rat aortic endothelial cells (RAECs) within a dynamic flow in vitro exposure system to more accurately depict the in vivo environment. A BC was formed on 20nm PVP-suspended Fe3O4 NPs following incubation in water, 10% normal or hyperlipidemic rat serum. Addition of BCs resulted in increased hydrodynamic size and decreased surface charge. More cholesterol associated with Fe3O4 NPs after incubation in hyperlipidemic as compared with normal serum. Using quantitative proteomics, we identified unique differences in BC protein components between the 2 serum types. Under flow conditions, formation of a BC from both serum types reduced RAECs association of Fe3O4 NPs. Addition of BCs was found to exacerbate RAECs inflammatory gene responses to Fe3O4 NPs (Fe3O4-hyperlipidemic > Fe3O4-normal > Fe3O4) including increased expression of IL-6, TNF-α, Cxcl-2, VCAM-1, and ICAM-1. Overall, these findings demonstrate that disease-induced variations in physiological environments have a significant impact NP-BC formation, cellular association, and cell response.

Prevalence and determinants of hypertension in Estonian adults

Background: Although Eastern Europe, including Estonia, has one of the highest morbidity and mortality rates associated with hypertension, there is little information in the literature concerning the biochemical risk factor profile or its association with hypertension in Estonia. This study examined the cross-sectional gender-stratified association between biochemical risk markers and hypertension in a population-based sample of adults in Estonia. Methods: The study was carried out in Tallinn, Estonia and consisted of 511 men and 600 women with a mean age of 46 years. Physiological measurements were taken and blood samples drawn to measure the following markers: cholesterol, high- and low-density lipoprotein cholesterol, apolipoproteins A-1 and B, lipoprotein(a), triglycerides, glucose, fibrinogen, high-sensitivity C-reactive protein and homocysteine. Results: Overall, 36% of participants had hypertension, with approximately 80% being aware of their condition. A total of 40% of participants reported taking antihypertensive medication. Multivariate binary logistic regression analysis showed that a decrease in high-density lipoprotein cholesterol and increases in age, body mass index, apolipoprotein B, triglyceride and homocysteine levels were associated with an increased probability of hypertension. Conclusions: Elevations in biochemical markers and cardiovascular risk factors are associated with hypertension. Increasing body mass index, triglyceride, apolipoprotein B and homocysteine levels with decreasing high-density lipoprotein cholesterol level should be investigated and monitored in Estonian adults.

High triglyceride level is associated with severe coronary artery disease in hypertensive subjects

BACKGROUND

The contribution of triglycerides (TG) to the extent of coronary artery disease (CAD) in hypertensive patients remained unclear.

METHODS

Consecutive 821 (aged 64.5+/-11.5 years, 482 males) hypertensive patients undergoing coronary angiography were included. The relationship of TG levels (<150 vs. > or =150 mg/dl) to the extent of CAD in all patients was examined by multiple logistic regression, adjusting for other CAD risk factors. In the lipid group, low levels of HDL were also adjusted.

RESULTS

Higher levels of TG were found in subjects with severe CAD compared to those with no or minimal CAD. The adjusted odds ratios for high levels of TG in the severe CAD subgroup versus the no or minimal CAD subgroup were 5.20 (95% CI, 3.13 to 8.63) in all patients and 7.51 (95% CI, 3.19 to 17.65) in the lipid group.

CONCLUSIONS

High levels of TG are strong clinical markers of greater extent of CAD in hypertensive subjects undergoing coronary angiography. The results may have clinical relevance for physicians in therapeutic decision making.

Hyperlipidaemia and its risk factors in the Guangxi Bai Ku Yao and Han populations

OBJECTIVE

To compare the differences in hyperlipidaemia prevalence and its risk factors between the Guangxi Bai Ku Yao and Han populations.

DESIGN

Cross-sectional study of hyperlipidaemia.

SETTING

Both populations were from Lihu and Baxu villages in Nandan County, Guangxi Zhuang Autonomous Region, People's Republic of China.

SUBJECTS

A total of 1170 healthy subjects of Bai Ku Yao and 1173 participants of Han Chinese aged 15-89 years were surveyed by a stratified randomized cluster sampling. Information on demographic, dietary and lifestyle characteristics was collected by standard questionnaires. Blood pressure, height, weight, waist circumference, serum lipids and apolipoproteins were measured, and BMI (kg/m2) was calculated as weight divided by the square of height.

RESULTS

The prevalence rates of hypercholesterolaemia, hypertriacylglycerolaemia and hyperlipidaemia in Bai Ku Yao and Han were 12.4 % v. 26.2 % (P < 0.001), 15.0 % v. 14.8 % (P > 0.05) and 24.4 % v. 33.9 % (P < 0.001), respectively. Hyperlipidaemia was positively correlated with BMI, waist circumference, total energy and total fat intakes, and negatively associated with physical activity and total dietary fibre intake in Bai Ku Yao (P < 0.05 to 0.001). Hyperlipidaemia was positively associated with age, alcohol consumption, BMI, waist circumference, total energy and total fat intakes, and inversely correlated with physical activity and total dietary fibre intake in Han (P < 0.05 to 0.001).

CONCLUSIONS

The prevalence of hypercholesterolaemia and hyperlipidaemia was significantly lower in the Bai Ku Yao than in the Han population, which might result from different dietary habits, lifestyle choices and physical activity level, as well as genetic factors between the two ethnic groups.

Diet, alcohol consumption, and serum lipid levels of the middle-aged and elderly in the Guangxi Bai Ku Yao and Han populations

Bai Ku Yao is an isolated subgroup of the Yao minority in China. The special customs and cultures including their clothing, intraethnic marriages, corn wine and rum intakes are still completely conserved to the present day. Little is known about the association of diet and alcohol consumption with serum lipid levels in this population. The aim of this study was to compare the differences in diet, alcohol consumption, and serum lipid levels of the middle-aged and elderly between the Guangxi Bai Ku Yao and Han populations. A total of 485 subjects of Bai Ku Yao and 501 participants of Han Chinese aged 40 and over were surveyed by a stratified randomized cluster sampling. Information on dietary intake and alcohol consumption was collected by standard questionnaires. Serum lipid levels were measured. Education level, height, weight, body mass index, waist circumference, blood pressure, hypertension, and total energy, fat, protein, dietary cholesterol, and salt intakes were lower in Bai Ku Yao than in Han (P < .05-.001), whereas physical activity level, carbohydrate, vegetal protein, and total dietary fiber intakes were higher in Bai Ku Yao than in Han (P < .001 for all). Serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) A1, and Apo B levels were lower in Bai Ku Yao than in Han (P < .001 for all). The levels of triglyceride, HDL-C, Apo A1, and the ratio of Apo A1 to Apo B in Bai Ku Yao were higher, but the levels of LDL-C and Apo B were lower in drinkers than in nondrinkers. The levels of triglyceride, HDL-C, LDL-C, Apo A1, Apo B, and the ratio of Apo A1 to Apo B in Bai Ku Yao were also influenced by the amount of alcohol consumed (P < .05-.001). High-density lipoprotein cholesterol levels in Han were higher and LDL-C levels were lower in drinkers than in nondrinkers (P < .01 for each). Serum total cholesterol, HDL-C, and LDL-C levels in Han were also associated with the amount of alcohol consumed (P < .05-.001). The differences in the lipid levels between the two ethnic groups may partially attribute to the differences in dietary habits and alcohol consumption.

Comparison of lipid levels, hyperlipidemia prevalence and its risk factors between Guangxi Hei Yi Zhuang and Han populations

BACKGROUND

Hyperlipidemia is a risk factor for atherosclerotic events. Differences in lipid levels may exist in different races. Han is the largest group and Zhuang is the largest minority among the 56 nationalities in China. Geographically and linguistically, Zhuang can be classified into 43 ethnic subgroups, among which Hei Yi (means black worship and black dress) Zhuang, living in Napo County bordering northeast Vietnam and with a population of about 50,000, is a special ethnic group, and the most conservative with a unique culture. Little is known about the lipid levels in this population. The aim of this study was to compare the lipid levels, prevalence of hyperlipidemia, and risk factors in Hei Yi Zhuang and Han populations.

METHODS

A total of 1068 people of Hei Yi Zhuang nationality were surveyed by a cluster sampling. Blood pressure, height, weight, serum lipid and apolipoprotein (Apo) levels were measured, and body mass index (BMI) was calculated. The results were compared with those in 933 people of Han nationality who also live in that district.

RESULTS

The levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, and Apo B in Hei Yi Zhuang nationality were significantly lower than those in Han nationality (p <0.05-0.001), but the levels of high-density lipoprotein cholesterol and the ratio of Apo A1 to Apo B in Hei Yi Zhuang nationality were significantly higher than those in Han nationality (p <0.001 and 0.05, respectively). The prevalence rates of hypercholesterolemia, hypertriglyceridemia, and hyperlipidemia in Hei Yi Zhuang and Han nationalities were 25.00 vs. 28.72% (p >0.05), 12.45 vs. 14.36% (p >0.05), and 31.37 vs. 35.91% (p <0.05); respectively. The prevalence of hyperlipidemia in Hei Yi Zhuang or Han population was positively correlated with age, BMI, blood pressure, and alcohol consumption (p <0.05-0.001), respectively, but was not associated with gender or cigarette smoking in both nationalities (p >0.05).

CONCLUSIONS

The current study reveals that there were significant differences in lipid levels and prevalence of hyperlipidemia between Hei Yi Zhuang and Han ethnic groups, but no significant differences in the detected risk factors for hyperlipidemia between the two ethnic groups, which might result from the comprehensive role of different dietary habits, life style, and level of physical activity, as well as genetic background.

Prevalence of Hyperlipidemia and Its Risk Factors for the Middle-Aged and Elderly in the Guangxi Hei Yi Zhuang and Han Populations

BACKGROUND

Han is the largest and Zhuang is the second largest among the 56 nationalities in China. Geographically and linguistically, Zhuang can be classified into 43 ethnic subgroups, among which Hei Yi (which means "black worship" and "black dressing") Zhuang is the most conservative group, according to its unique culture and customs. Little is known about the lipid profiles and corresponding risk factors of hyperlipidemia in this population. Therefore, the aim of this study was to compare the effects of demographic characteristics, health-related behaviors, and lifestyle factors on the prevalence of hyperlipidemia for the middle-aged and elderly in the Guangxi Hei Yi Zhuang and Han populations.

METHODS

A sample of 657 people of Hei Yi Zhuang aged 40 years and over was randomly selected from 7 villages in Napo County, Guangxi, China. Information on demographic characteristics, health-related behaviors, and lifestyle factors was collected by questionnaire. Blood pressure, height, weight, waist circumference, and serum lipid and apolipoprotein (apo) levels were measured, and body mass index (BMI) was calculated as a measure of weight relative to height. The results were compared with those in 520 people of Han living in the same region.

RESULTS

The prevalence of hyperlipidemia in the Hei Yi Zhuang was significantly lower than that in the Han (36.2% vs 42.3%; p < .05). The levels of total cholesterol, triglyceride, low-density lipoprotein cholesterol, and apo B in Hei Yi Zhuang were also significantly lower than those in the Han (p < .05 to .001), but the levels of high-density lipoprotein cholesterol and the ratio of apo A-I to apo B in the Hei Yi Zhuang were significantly higher than those in the Han (p < .01 and < .001, respectively). There were no significant differences in apo A-I levels between the two ethnic groups (p > .05). The prevalence of hyperlipidemia was positively correlated with BMI and blood pressure in the Hei Yi Zhuang. Hyperlipidemia was positively associated with age, BMI, and blood pressure and negatively associated with gender (female higher) in the Han.

CONCLUSIONS

In the present study of the middle-aged and elderly population, the Hei Yi Zhuang have a more favorable lipid profile and a lower prevalence of hyperlipidemia than do the Han, and there is also a significant difference in the risk factors for hyperlipidemia between the two ethnic groups, which might result from the effects of different demographic characteristics, health-related behaviors, and lifestyle factors.

Lipoprotein Levels Are Associated with Incident Hypertension in Older Adults

OBJECTIVES

To determine the relationship between baseline measures of serum lipoproteins and incident hypertension in older adults.

DESIGN

Prospective cohort study.

SETTING

Pittsburgh, Pennsylvania, site of Systolic Hypertension in the Elderly Program (SHEP).

PARTICIPANTS

One hundred eighty-seven men and women (mean age 71.3), normotensive (systolic blood pressure (SBP) <160 mmHg, diastolic blood pressure (DBP) <90 mmHg) at baseline, were followed annually over 8 years as an ancillary study to the SHEP.

MEASUREMENTS

Hypertension development, defined as initiation of antihypertensive therapy or SBP greater than 160 mmHg or DBP greater than 90 mmHg. Lipoprotein measures included total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), HDL(2)-C, HDL(3)-C, triglycerides, and apolipoproteins 1, 2, and B.

RESULTS

Over 8 years, 44 participants developed hypertension, for a Kaplan-Meier cumulative incidence rate of 31% (95% confidence interval (CI)=23-39%). Cumulative incidence rates were highly associated with baseline SBP, ranging from 8% in those with baseline SBP less than 120 mmHg to 70% in those with SBP of 140 to 159 mmHg. Other univariate associations included higher DBP, pulse pressure (P <.01 for both), triglycerides (P=.03), apolipoprotein B (P=.03), and lower HDL-C (P=.04) and HDL(3)-C (P=.02). In multivariate Cox regression analysis, higher baseline SBP (relative risk (RR)=1.8 per 10 mmHg, 95% CI=1.5-2.3) and lower HDL(3)-C (RR=0.8 per 5 mg/dL, 95% CI=0.42-1.0) remained significant independent predictors of time to hypertension.

CONCLUSION

Older adults with abnormal serum lipoproteins are at increased risk of developing hypertension. Clinical trials exploring the effects of the modification of lipoprotein levels on hypertension incidence rates are needed.

Is epsilon4 allele of apolipoprotein E associated with more severe end-organ damage in essential hypertension?

The aim of the present study comparing patients with mild to moderate hypertension with controls, was to explore a possible association between hypertension-related target organ damage and evaluation found in the gene encoding apolipoprotein E (apo E) genotype. Detailed medical history was recorded and physical examination was performed for all patients in the study (88 hypertensives, 63 normotensive controls). PCR (Polymerase Chain Reaction), RFLP (Restriction Fragment Length Polymorphism), and agarose gel electrophoresis techniques were used to determine the apo E genotypes. The frequencies of apo epsilon2, apo epsilon3, and apo epsilon4 alleles were 3.97, 88.06, and 9.95%, respectively in the hypertensive group. The frequencies of apo epsilon2, apo epsilon3, and apo epsilon4 alleles were 5.5, 92.0, and 2.38%, respectively in the control group. There were about twice as many individuals in the heterozygote hypertensive group who had apo E3/4 as compared to the control group (7.30 vs. 2.38%) (p = 0.07). The hypertensive patients who were carriers of the apo epsilon4 had significantly higher organ damage (left ventricular hypertrophy (p < 0.001). dilated left atrium (p < 0.05), retinopathy (p < 0.05)) as compared to those who were not carriers of apo epsilon4. These results showed a trend for the epsilon4 allele to be associated with a higher prevalence of target organ damage in patients with mild to moderate hypertension.

Malignant hypertension is accompanied by marked alterations in chylomicron metabolism

Malignant hypertension (MH) is a severe complication of untreated arterial hypertension that damages the vascular system. It is often accompanied by disturbances in lipid metabolism that could contribute to its pathophysiology. We examined chylomicron metabolism in MH patients using a triglyceride-rich emulsion known to mimic natural chylomicrons when injected into the bloodstream. The emulsion was labeled with [3H]triolein and [14C]cholesteryl oleate and injected intravenously into 15 normolipidemic MH patients aged 29 to 56 years (8 men) for comparison with 17 healthy control subjects. Consecutive plasma samples were taken at regular intervals during 1 hour for determination of the disappearance curves of the labels. The fractional clearance rate of the [3H]triolein emulsion in MH patients was twice as small as that of control subjects (0.061 +/- 0.012 and 0.141 +/- 0.074 min-1, respectively). On the other hand, [14C]cholesteryl oleate fractional clearance rate was not statistically different in MH patients and control subjects (0.032 +/- 0.004 and 0.056 +/- 0.014 min-1, respectively). These results indicate that in MH, lipolysis (measured by the fractional clearance rate of [3H]triolein) is pronounced diminished, whereas the removal of the remnant particles (measured by the fractional clearance rate of [14C]cholesteryl oleate) is not importantly affected. In conclusion, there is an alteration in the circulatory transport of dietary lipids that may be an important component in the vascular disease associated with MH.

Dyslipoproteinemic changes in borderline hypertension

The present study examined plasma lipoprotein, lipoprotein lipase, hepatic lipase, and insulin levels in men with borderline hypertension (diastolic blood pressure 85 to 94 mm Hg) compared with age-matched normotensive control subjects (diastolic blood pressure less than or equal to 80 mm Hg, n = 75 + 75). High-density lipoprotein (HDL) subclasses were determined in a subset (n = 45 + 45). While total and low-density lipoprotein cholesterol levels were similar, levels of very-low-density lipoprotein (VLDL) cholesterol and triglycerides (0.46 versus 0.41 mmol/L, P = .027, and 1.0 versus 0.85 mmol/L, P = .031) and total triglycerides (1.53 versus 1.33 mmol/L, P = .009) were elevated and HDL cholesterol was reduced in the borderline group compared with the normotensive group (1.17 versus 1.26 mmol/L, P = .043). The HDL subclass HDL2b concentration was lower (0.16 versus 0.24 mmol/L, P = .006), while HDL3b and HDL3c concentrations were higher in the borderline group (0.38 versus 0.32 mmol/L, P = .016, and 0.19 versus 0.16 mmol/L, P = .042). Significantly higher activities of hepatic lipase in the borderline group (282 versus 232 mU/mL, P = .024) and significant correlations between lipoprotein lipase activity and VLDL and HDL concentrations suggest an involvement of these enzymes in the development of these differences. When adjusted for body mass index or insulin level, all differences disappeared, except for HDL3b and HDL3c concentrations, which remained significantly elevated. These results indicate that dyslipoproteinemic changes are present in early hypertension. Although most of these changes are related to obesity, alterations in HDL profile were not explained by influences of body mass index and insulin.

Dubbo Study of the elderly: hypertension and lipid levels

Untreated hypertension in age groups below 60 years has been shown to be associated with significant elevations in serum cholesterol and triglyceride levels. Drug therapy of hypertension has also been shown to have adverse effects on lipoproteins. We have investigated lipid and lipoprotein levels in a community-based sample of men and women 60 years and older belonging to one of the following groupings: (a) normal blood pressure (n = 1075); (b) untreated hypertension (n = 329); (c) drug-treated hypertension (n = 880). Serum lipid, lipoprotein, apolipoprotein or plasma glucose levels did not vary significantly between untreated hypertensives and normotensives of either sex. In a multiple regression model controlling for possible influences of age, overweight, alcohol and tobacco usage, and presence of coronary heart disease, anti-hypertensive drug therapy significantly predicted increased serum triglycerides (P less than 0.001) and reduced high density lipoprotein (HDL) cholesterol levels (P less than 0.01) in both sexes, reduced apolipoprotein A-I levels in males (P less than 0.001), and increased apolipoprotein B (P less than 0.01) and plasma glucose levels (P less than 0.001) in females. Adjusted triglycerides were 20% higher and HDL cholesterol was 7% lower in the presence of anti-hypertensive drug therapy. These effects were partially consistent with the known actions of thiazide diuretics and beta-blockers which were used by more than 50% and 40% of subjects, respectively.

Effects of adrenoreceptor antagonists and agonists on clearance of emulsion models of triacylglycerol-rich lipoproteins from plasma in rats

1. We previously found that adrenaline and noradrenaline exert essentially opposite effects on clearance from plasma of chylomicron-like emulsions injected intravenously in rats, suggesting mechanisms that may be implicated in the atherogenic effects of chronic stress and hypertension and conversely in the protective effect of regular exercise. 2. The mechanisms underlying the effects of adrenaline and noradrenaline have now been investigated. Chronic adrenergic blockade with either the alpha 1-receptor antagonist doxazosin or the beta-receptor antagonist propranolol slowed the clearance of labelled emulsion lipids from plasma of normal Wistar rats. The results with doxazosin were unexpected in view of its capacity to decrease plasma triglycerides in patients. 3. In spontaneously hypertensive rats (SHR) the clearance of triolein (TO) was very slow compared with normal Wistar rats. Emulsion TO clearance provides a measure of lipolysis by lipoprotein lipase, and a defect in clearance indicates either defective enzyme action or poor perfusion of capillary beds rich in enzyme. Defective enzyme activity in SHR was excluded, suggesting redistribution of blood flow away from skeletal muscle and adipose tissue. In SHR the TO clearance from injected chylomicron-like emulsions was improved by blockade with doxazosin compared with control untreated SHR. 4. The beta 2-adrenoreceptor agonist Fenoterol was infused intravenously during clearance of an injected lipid emulsion. Clearance of radiolabelled cholesteryl oleate (CO) was clearly slowed while there was a lesser reduction of TO clearance rate. Emulsion CO clearance provides a measure of the uptake of lipoprotein remnants by the liver, and a defect in clearance of CO indicates either defective ligand (apolipoprotein E)-receptor interaction or decreased perfusion of the splanchnic bed. Isoprenaline, a non-selective beta-adrenergic agonist, gave similar results. Both compounds reduced mean arterial pressure by about 20-40 mm Hg at the doses employed, indicating that the beta 1 (cardiac) effect of the isoprenaline was insufficient to offset its vasodilatatory effect on skeletal muscle arterioles (beta 2). 5. The alpha-agonist phenylephrine, at a dose which moderately raised mean arterial pressure, slowed clearance of both TO and CO for the first 12 min after injection of emulsion but at later time points clearances caught up with the controls. 6. Administration of a mixture of isoprenaline and phenylephrine produced definite enhancement of both TO clearance and CO clearance. The effect of the mixture was opposite to the effects of of either agonist alone, demonstrating clearly that direct effects on lipoprotein lipase activity or receptor mediated processes were not involved.(ABSTRACT TRUNCATED AT 400 WORDS)