Effects of antihypertensive therapy on serum lipoproteins.

Several drugs used for standard antihypertensive therapy may also interact with the lipoprotein metabolism. The following has been observed after 1 to 12 months of treatment. Various thiazide-type diuretics may significantly increase the potentially atherogenic serum low-density-lipoprotein cholesterol (LDL-C) and/or very-LDL-C-fractions, while the antiatherogenic high-density-lipoprotein cholesterol (HDL-C) is largely unchanged. Certain loop-diuretics also increase the LDL-C/HDL-C ratio and both types of diuretics elevated serum triglycerides (Tg) in some but not all studies. LDL-C was increased in diuretic-treated men and in chlorthalidone-treated postmenopausal women, but not in chlorthalidone-treated premenopausal women. The latter may be protected from this effect. Only two diuretics evaluated, namely indapamide and spironolactone, had no apparent influence on lipoproteins. Beta-blocker monotherapy may often increase Tg and slightly decrease HDL-C. The magnitude of these changes did not distinctly differ between highly cardioselective and nonselective beta-blockers, but it was less pronounced on beta-blockers than on those without intrinsic sympatholytic activity. Other sympatholytics such as reserpine, methyldopa, clonidine, debrisoquine, the alpha-beta-blocker labetalol, or the postsynaptic alpha-blocker, prazosin, did not affect or even slightly decrease Tg or total C, LDL-C, and very-LDL-C values. With combinations, a tendency for increased Tg and lower HDL-C was also apparent during thiazide-type diuretic-beta-blocker therapy. However, diuretic-induced increases in LDL-C were prevented or reversed by concomitant beta-blockade, but not by reserpine, methyldopa, or clonidine. Monotherapy with the potent direct vasodilator, carprazidil, improved blood pressure and significantly increased HDL-C. Prospective long-term studies are needed to clarify the course and the pathogenic and prognostic relevance of lipoprotein changes induced by certain diuretics or beta-blockers.

Serum lipoproteins during treatment with the antihypertensive agent indapamide.

Considering the documented, potentially undesirable influence of various thiazide-type or loop diuretics on serum lipoproteins, we prospectively investigated in 69 men (mean age +/- SEM, 32 +/- 1 years) the metabolic effects of the new diuretic-antihypertensive compound indapamide. Compared to placebo, indapamide (2.5 mg/day) given for 6 to 8 weeks lowered (p less than 0.02 to less than 0.001) blood pressure (supine values from 148/98 +/- 3/2 to 137/93 +/- 3/2) in 29 men with mild to moderate essential hypertension, but not in 40 healthy men. In both groups, significant (p less than 0.05 to less than 0.001) decreases in body weight (-0.8 kg) and plasma potassium (-0.6 mmol/L), and increases in plasma uric acid (+20%), renin activity (+200%), and aldosterone documented good compliance. There were no significant changes in total cholesterol (in all subjects, from 208 +/- 6 to 213 +/- 6 mg/dl), low- or very low-density lipoprotein (VLDL) cholesterol (127 +/- 6 to 129 +/- 6 and 21 +/- 1 to 21 +/- 2 respectively), high-density lipoprotein cholesterol (50 +/- 1 to 51 +/- 1 mg/dl), total triglycerides (Tg) (108 +/- 5 to 112 +/- 6 mg/dl), VLDL-Tg, apoproteins A1 and A2, plasma glucose, epinephrine, norepinephrine, sodium, calcium, magnesium, and creatinine; apoprotein B (84 +/- 2 to 88 +/- 3 mg/dl) and plasma insulin after glucose loading dose tended to be increased minimally. The absence of distinct lipoprotein alterations after short-term indapamide treatment may be of clinical and epidemiological interest.

Alpha-1-adrenergic blockade and lipoprotein metabolism in essential hypertension.

The effect of the selective alpha 1-antagonist terazosin on serum lipoproteins and certain blood pressure-regulating factors was assessed in 15 patients with essential hypertension. Terazosin given during 8 weeks reduced arterial pressure (from 153/103 +/- 3/2 (SE) to 143/96 +/- 5/2 mm Hg; P less than 0.02) but did not modify body weight, heart rate, blood volume, plasma renin activity, aldosterone and catecholamine levels, or serum cholesterol, triglycerides, and their lipoprotein fractions. In nine of the patients, blood pressure control was not achieved with terazosin monotherapy and the diuretic methyclothiazide, 2.5 mg, was added. After 8 weeks of combined treatment, blood pressure decreased further (P less than 0.05); serum lipids and lipoprotein fractions did not change as compared with placebo or terazosin conditions. These findings indicate that terazosin in monotherapy does not unfavorably influence lipid metabolism.

Salt and hypertension: data from the "Heidelberg Study".

Prevalence of hypertension and "intake" of sodium chloride (as estimated from 24-hr urinary Na-excretion) were measured in a random sample (n = 800) of 20- to 40-year-old Heidelberg men. There was a high (14%) prevalence of hypertension and a high (mean = 11.32 g) NcCl intake; both showed, however, no correlation. The lack of a NaCl/blood pressure correlation in this cross-sectional study might be due to intra- and interindividual variability of both parameters and, possibly, to a "threshold" argument concerning the etiological role of sodium in hypertension.

Probucol in hypercholesterolemia. A double blind study.

The effect of Probucol on serum lipids, lipoproteins and the apoproteins A1, A2 and B was studied in 27 patients with primary hypercholesterolemia. After 3 months of dietary treatment and a 6 week placebo period the patients received 4 X 250 mg of Probucol or placebo per day for 4 months in a double blind design. Total and LDL-cholesterol were significantly reduced with Probucol (13% and 16% respectively) in addition to the diet. Apo B showed a 12% decrease. The HDL cholesterol concentration as well as the serum triglycerides and triglyceride-rich lipoproteins were not significantly altered. Both apo A1 and apo A2 were markedly reduced under Probucol treatment. In general the subjective and objective tolerance of the drug was good.

Reversal or prevention of diuretic-induced alterations in serum lipoproteins with betablockers.

In 18 patients with essential hypertension serum low density lipoprotein cholesterol (LDL-C) was significantly (P less than 0.001) increased following short-term chlorthalidone therapy, but not during combination therapy with chlorthalidone and a betablocker. This tendency was similar in two subgroups which were studied with an inverse sequence of drug administration. In Group I (11 men), a 22% increase (P less than 0.01) in LDL-C during chlorthalidone monotherapy was restored to normal 6 weeks after addition to a betablocker to the diuretic; in Group II (5 men, 2 postmenopausal women) LDL-C levels were increased by 41% (P less than 0.05) 6 weeks after withdrawal of the betablocker from the combination therapy. No significant changes occurred during either the treatment phase in high density lipoprotein cholesterol or apoprotein B levels. It is concluded that combination therapy with a betablocker may prevent or reverse an increase in serum LDL-C associated with short-term chlorthalidone monotherapy.

Apoproteins and lipids as discriminators of severity of coronary heart disease.

Serum apoprotein and lipid concentrations were measured in 63 patients undergoing coronary angiography. Thirty-eight patients had 50% or higher grade stenoses, 25 had chest pain, but no significant stenoses. Among the patients with higher grade stenoses 71% had hyperlipoproteinemias as opposed to 12% in patients without stenoses. As compared to suitable normal controls, patients with angiographically documented coronary heart disease showed significant changes in all lipid and apoprotein concentrations under study. However, differences between the two patients groups were also noted. Among these, apo A-I, A-II and B, total cholesterol and LDL cholesterol were statistically significant. These results indicate that apoprotein A and B levels, total cholesterol and LDL cholesterol are good discriminators of the severity of coronary heart disease, while HDL cholesterol is a more suitable parameter for epidemiological studies.

Reduced LDL- and increased HDL-apoproteins in patients with hypercholesterolaemia under treatment with bezafibrate.

The effect of bezafibrate on serum lipids, lipoproteins and the apoproteins A-I, A-II and B was studied in 18 patients with primary hypercholesterolaemia. Total cholesterol was lowered by 20% (P less than 0.05), LDL-cholesterol by 24% (P less than 0.05), and apo B by 14% (P less than 0.05), which is comparable to the effect obtained with anion exchange resins but with far fewer side-effects. HDL increased significantly during bezafibrate treatment both by measurement of HDL-cholesterol (+54%, P less than 0.05) and by the determination of HDL-apoproteins A-I (+ 19%, P less than 0.05) and A-II (+ 23%, P less than 0.05). This increase of HDL and the decrease of triglycerides was maintained for 6 weeks of placebo treatment after cessation of bezafibrate, while serum total and LDL cholesterol as well as apo B returned to their baseline levels.

Lipoprotein fractions, lipoprotein lipase and hepatic triglyceride lipase during short-term and long-term uptake of ethanol in healthy subjects.

In short-term experiments, healthy fasting persons were given a basic dose of 0.5 g of ethanol/kg body weight, followed by hourly maintenance doses of 0.15 g of ethanol/kg body weight. After 10 h there was a significant increase of triglycerides in the VLDL, LDL, and HDL, the main rise (from 42 to 92 mg/dl) being found in the VLDL triglycerides. Other subjects, who received nourishment isocaloric with ethanol, likewise showed a significant rise of triglycerides in all lipoprotein fractions. Chylomicron triglycerides increased from 9.3 to 35.5 mg/dl. There was no significant change in postheparin HTGL, but postheparin LPL activity decreased after 10 h from 17.9 to 12.2 mmol FFA/ml/h in the fasting subjects, and from 28.5 to 10.2 mmol/FFA/ml/h in the persons receiving food. In long-term experiments after 4 weeks of 70 - 80 g of ethanol and isocaloric food daily, triglycerides increased, especially in the VLDL (from 50 to 82 mg/dl). The increase in the HDL, however, was also significant. After 4 weeks of ethanol, the chylomicron triglycerides in the plasma of the fasting subjects reached a value of 29.3 mg/100 ml, LDL cholesterol decreased, and HDL cholesterol increased. After 4 weeks of ethanol there was an increase in the lipoprotein lipase of the adipose tissue.

Secondary type II hyperlipoproteinemia in patients with anorexia nervosa.

In 18 patients with anorexia nervosa, plasma cholesterol and triglyceride concentral concentrations were repeatedly determined over a period of 14 mo. In 11 patients elevated cholesterol concentrations were found which were due to an increase of low-density lipoprotein cholesterol, whereas high-density lipoprotein and very low density lipoprotein cholesterol levels were in the normal range. The elevated cholesterol values did not correlate with clinical and laboratory parameters such as the degree of weight loss and thyroid function tests. In follow-up studies it could be shown that in patients who regained their original weight, elevated plasma cholesterol concentrations fell to normal levels parallel to weight increase. In patients who showed no change in weight, however, cholesterol levels remained high. The cause for this secondary type II hyperlipoproteinemia in anorexia nervosa is not known. Hepatic triglyceride lipase and lipoprotein lipase activities in post-heparin plasma were found to be low despite normal triglyceride concentrations.

Reversal of diuretic-induced increases in serum low-density-lipoprotein cholesterol by the betablocker pindolol.

Seventeen patients with mild to moderate essential hypertension received during three consecutive 4 wk periods a matched placebo, the thiazide-like diuretic, clopamide in a low dosage of 5 mg/day, or this diuretic combined with the betablocker, pindolol in a low dosage of 10 mg/day. Compared to placebo conditions, clopamide monotherapy significantly increased serum low-density lipoprotein cholesterol (LDL-C) by 13% (p less than 0.025). Following addition of pindolol, serum LDL-C was restored to control values. These variations in serum LDL-C were unrelated to concomitant changes in blood pressure, plasma potassium, renin activity or aldosterone levels. Blood pressure in the supine position was reduced from 152/99 +/- 13/9 mm Hg (+ SD) to 141/93 +/- 15/7 mm Hg following diuretic-monotherapy and to 139/90 +/- 12/9 mm Hg following diuretic-betablocker combination treatment. These findings suggest that antihypertensive combination treatment with low doses of clopamide and pindolol is not only effective and well tolerated, but may also avoid the increase in serum LDL-C levels occurring when the thiazide-like diuretic is given alone.

Increased serum high-density lipoprotein cholesterol in hypertensive men treated with the potent vasodilator carprazidil.

The effects of the potent arteriolar vasodilator carprazidil on serum lipoproteins and various clinical, biochemical and endocrine parameters were assessed in 15 men with mild to moderate essential hypertension. Following a carprazidil monotherapy (average dose 50 to 60 mg/d) of 8 weeks (N = 15) or 16 weeks (N = 12) duration, blood pressure was decreased significantly (P less than 0.01), while serum high-density lipoprotein cholesterol (+ 26% and + 24%, respectively; P less than 0.01) and the alpha-lipoprotein fraction (+ 26% and + 41%) were increased. Low- and very low-density lipoprotein cholesterol, triglycerides, as well as mean body weight, blood and plasma volume, heart rate, and plasma renin, aldosterone, norepinephrine, and epinephrine were not consistently altered. These results indicate that treatment of hypertensive men with carprazidil in modest dosage may have a favorable influence both on blood pressure and serum lipoproteins.

Increased serum low-density lipoprotein cholesterol in men treated short-term with the diuretic chlorthalidone.

The effect of the diuretic chlorthalidone (100 mg/day for 6 weeks) on serum lipoproteins was evaluated in 37 subjects. In 19 men with essential hypertension (aged 41 +/- 3 yr), 8 normal men (26 +/- 3 yr), or all of these men considered together, chlorthalidone significantly increased serum low density lipoprotein--cholesterol (LDL-C) by 20% (p less than 0.05 to less than 0.01). There was also a tendency for increased LDL-C in seven postmenopausal women (+/- 15%) but not in three premenopausal women with essential hypertension. High density lipoprotein--cholesterol was not significantly changed in hypertensive women or normal men and decreased slightly (p less than 0.05) in hypertensive men. Apolipoproteins A-I, A-II, and B were not changed significantly in women or men. Diuretic-induced lipoprotein alterations were not associated with altered plasma volume and unrelated to variations in serum potassium, glucose, insulin levels, blood pressure, and body weight. Short-term diuretic therapy with chlorthalidone may increase serum LDL-C in young or middle-aged men with normal or high blood pressure.

Effects of indapamide and various diuretics alone or combined with beta-blockers on serum lipoproteins.

A prospective evaluation was started in 1976 to study the influence of diuretics alone or combined with beta-blockers on serum lipoproteins in normal or hypertensive subjects. Compared to placebo conditions, 4 or 6-weeks' monotherapy with various diuretics significantly (p less than 0.05) increased the beta-lipoprotein fraction (furosemide, 80 mg/day or chlorthalidone, 100 mg/day; n = 16) or low-density lipoprotein-cholesterol (LDL-C) (chlorthalidone, 100 mg/day, n = 27 men; tienilic acid, 250 mg/day, n = 16 men, clopamide, 5 mg/day, n = 17 men; or muzolimine, 20 to 40 mg/day, n = 13 men or post-menopausal women). No increase in LDL-C was noted in 43 men (32 normal, 11 with mild hypertension) treated with indapamide, 2.5 mg/day. Serum high-density lipoprotein-cholesterol and apoproteins A1, A2 and B were not consistently changed by any of these agents. In women, chlorthalidone (100 mg/day) significantly increased LDL-C in the (100 mg/day) significantly increased LDL-C in the post-menopausal (n = 18) but not in the pre-menopausal (n = 22) state. Increases in LDL-C caused by chlorthalidone monotherapy were prevented or reversed by the addition of a beta-blocker, usually propranolol or atenolol (n = 18); increases in LDL-C during clopamide monotherapy were reversed after the addition of the beta-blocker pindolol (10 mg/day, n = 17). In all studies, variations in beta-lipoprotein or LDL-C levels could not be explained by changes in blood volume, serum glucose or insulin and did not correlate with alterations in blood pressure, plasma potassium, renin, aldosterone, adrenaline or noradrenaline. These observations indicate that various diuretics may increase serum LDL-C in men or post-menopausal women. Pre-menopausal women may often be protected from this side-effect. Long-term studies are now needed to clarify the pathogenic and prognostic relevance of lipoprotein changes induced by diuretics. In the meantime, it is of clinical interest that indapamide had no significant effect on serum lipoproteins and that certain beta-blockers appear to prevent or reverse increases in LDL-C during diuretic treatment in men and post-menopausal women.

Quantitation of apolipoprotein B by polyclonal and monoclonal antibodies.

A non-competitive sandwich enzyme linked immunosorbent assay for the quantitation of apolipoprotein B with polyclonal and monoclonal antibodies was developed. Polyclonal antibodies were used as 'coater'. In the assay with polyclonal antibodies, the same antibody was used as conjugate with alkaline phosphatase. For studies with monoclonal antibodies, enzyme conjugated anti-mouse immunoglobulin had to be used, since monoclonal antibodies lost their reactivity upon enzyme conjugation. Two murine monoclonal antibodies were employed: MAB B-1 with specificity for apolipoproteins (Apo) B-48 and B-100 and MAB B-5 with specificity for B-100 (Radioimmunoassay Inc.). In a reference group Apo B values of 0.82 +/- 0.20 g/l were measured with polyclonal antibodies, 0.68 +/- 0.19 g/l and 0.95 +/- 0.33 g/l with MAB B-1 and MAB B-5. In pure hypercholesterolemia, a similar increase was found with all three antibodies, while in combined hyperlipoproteinemia MAB B-5 gave greater than 40% lower values. Differences were also found with respect to the correlation between Apo B and cholesterol or triglycerides.

Risk factor interactions for coronary heart disease.

There is now an increasing awareness of the atherogenicity of the individual lipoprotein subfractions. In addition, the effects of commonly used antihypertensive drugs has been a cause for concern. Thiazides and loop diuretics both increase LDL cholesterol, but indapamide and spironolactone have no apparent effects. Beta-blocker monotherapy may also increase triglycerides whilst post-synaptic alpha-blockers do not affect, or slightly lower triglycerides, total cholesterol, LDL and VLDL levels.

Lipoprotein changes in familial hypercholesterolemia after extracorporeal immunoadsorption of low density lipoproteins.

The effects of extracorporeal immunoadsorption of LDL on the lipoprotein metabolism in two patients with familial hypercholesterolemia are reported. The immunoadsorbent consisted of F(ab')2 fragments of sheep anti-LDL antibodies, which had been coupled to Sepharose CL 4B. Within a time period of 3 to 3.5 hours a mean reduction of the level of total cholesterol by 76 +/- 4 p. cent could be obtained. The level of LDL cholesterol was reduced by 78 +/- 4 p. cent and the level of apo. B by 84 +/- 5 p. cent. Both LDL and VLDL were bound to the immunoadsorbent, while HDL was predominantly lowered by the plasma-dilution, which was in the order of 20 p. cent. The same was true for other serum proteins, not related to LDL or VLDL. The relative distribution of the different lipoprotein classes was again reached 3 days after the treatment, the initial lipid and apolipoprotein levels two to three weeks after the treatment. In a long-term therapy consisting of 45 treatments with a mean interval of 18 days between two treatments a mean cholesterol lowering of 42 p. cent could be achieved. No adverse effects and no sensitization to be heterologous protein were observed.