[Diuretics in the treatment of hypertension. Efficacy, safety and tolerability]. / Therapie der Hypertonie mit Diuretika. Wirksamkeit, Sicherheit und Verträglichkeit.

In the treatment of hypertension, both the thiazide diuretics hydrochlorothiazide and bendroflumethiazide and the "thiazide-like" diuretics chlorthalidone and indapamide are used. Guidelines refer to these as the class of thiazide diuretics suggesting their interchangeability. However, bendroflumethiazide and hydrochlorothiazide, at least in the commonly used low dose range, are less potent with respect to blood pressure lowering and may also be less effective in preventing morbidity and mortality events. This is of great clinical relevance since hydrochlorothiazide is by far the most widely prescribed diuretic. Increasing the dose of hydrochlorothiazide would further reduce tolerability of treatment due to an increase in dose-dependent side effects. The underlying mechanisms of the suggested superiority of chlorthalidone on cardiovascular morbidity and mortality remain unclear. The half-life of chlorthalidone has been estimated at >50 h thus exceeding the half-life of hydrochlorothiazide by about 5-fold. Given the documented irregular intake of antihypertensive drugs, the prolonged efficacy of chlorthalidone makes this agent a "forgiving drug" with a definite advantage over hydrochlorothiazide. On the basis of the available evidence, whenever diuretic treatment is indicated in a hypertensive patient, a thiazide-like agent, preferably chlorthalidone should be employed.

Triple-combination therapy in the treatment of hypertension: a review of the evidence.

Hypertension is a serious public health concern with inadequate control of blood pressure (BP) worldwide. Contributing factors include low efficacy of drugs, underuse of combination therapies, irrational combinations, physicians' therapeutic inertia and poor adherence to treatment. Current guidelines recommend the use of initial (dual) combination therapy in high-risk patients for immediate BP response, better short- and long-term BP control, and continued/improved patient adherence. This article aims to review the existing evidence of triple-combination therapies with respect to efficacy, safety and adherence to treatment. It is estimated that three drugs are required to achieve BP control in approximately one-fourth to one-third of patients. Randomised controlled trials (RCTs) have shown that triple combinations of amlodipine/valsartan/hydrochlorothiazide, amlodipine/olmesartan/hydrochlorothiazide and amlodipine/telmisartan/hydrochlorothiazide produce greater BP reductions, with greater proportions of patients achieving BP control compared with dual therapies. Further evidence also demonstrates that triple-combination therapy is efficacious for moderate to severe hypertension, with substantial additional BP reduction over dual regimens. Both RCTs and post-marketing observational studies have shown consistent and comparable efficacy in both the general population and high-risk hypertensive subgroups. Triple therapies are generally well tolerated with adverse event profiles similar to dual regimens. In addition, fixed-dose combinations used as single pill improve patient adherence leading to better long-term BP control. Depending on regional circumstances, they may also be cost effective. Thus, single-pill triple combinations of different classes of drugs with complementary mechanisms of action help to treat patients to goal with improved efficacy and better adherence to treatment.

The plasminogen activator inhibitor 1 4G/5G polymorphism is not associated with longevity: a study in octogenarians.

Accumulating evidence suggests that plasma levels of the plasminogen activator inhibitor 1 (PAI-1) may modulate the risk of coronary artery disease. The regulation of PAI-1 levels underlies not only environmental but also genetic influences. The 4G/5G polymorphism of the PAI-1 gene has recently gained additional relevance as a possible cardiovascular risk factor, as the 4G allele may be associated with enhanced expression of the PAI-1 gene. This retrospective cohort study examined the effect of the PAI-1 4G/5G genotype on longevity among 205 subjects aged 80 years and older. Such studies in larger cohorts have recently become available along with new methods for the rapid and easy determination of gene polymorphisms. We utilized a light-cycler assisted method which is a fast and flexible method of analyzing the PAI-1 4G/5G polymorphism on the gene level. In these 205 persons the 4G/5G allele was found in 96 persons (47%), the 4G/4G variant in 62 (30%), and the 5G/5G allele in 47 (23%). These data are similar to the allele distribution described in other large cohorts not restricted to old age. Thus the results of this study are not suggestive of an important contribution of the PAI-1 genotype on total mortality.

Renal denervation: unde venis et quo vadis?

OBJECTIVE AND METHODS: Renal denervation is a minimally invasive, catheter-based option for the treatment of refractory hypertension. Indications and contraindications for renal denervation have been defined in an interdisciplinary manner. The efficacy and safety of the procedure were evaluated. RESULTS: Currently, indication for renal denervation is limited to patients with primary hypertension and a systolic blood pressure of ≥ 160 mm Hg (or ≥ 150 mm Hg in diabetes type 2) despite optimal medical therapy with ≥ 3 different antihypertensive drugs. In this specific patient population, an average blood pressure reduction of 32/14 mmHg was observed in non-randomized/-controlled trials after renal denervation. These results were not confirmed in the first randomized controlled trial with a non-significantly superior blood pressure reduction of 14.1 ±â€Š23.9 mm Hg compared to controls (-11.74 ±â€Š25.94 mm Hg, difference -2.39 mm Hg p = 0.26 for superiority with a margin of 5 mm Hg) who underwent a sham procedure. CONCLUSION: The efficacy and long-term effects of renal denervation need to be re-evaluated in light of the HTN3 study results. To date, renal denervation should not be performed outside of clinical trials. Future trials should also assess if renal denervation can be performed with sufficient safety and efficacy in patients with hypertension-associated diseases. The use of renal denervation as an alternative therapy (e. g. in patients with drug intolerance) can currently not be advocated. KEY POINTS: The indication for renal denervation should be assessed in an interdisciplinary fashion and according to current guidelines with a special focus on ruling out secondary causes for arterial hypertension. 5 - 10 % of patients with hypertension suffer from refractory hypertension, but only about 1 % of patients meet the criteria for a renal denervation. Renal denervation leads to a significant decrease in office blood pressure; however, the impact on 24-hour blood pressure measurements remains unclear. In the first randomized controlled trial on renal denervation with a control group undergoing a sham procedure, blood pressure reduction failed to reach the anticipated level of superiority over best medical treatment. Periprocedural complications are rare, but long-term safety can currently not be appraised due to the limited data available.

Renal denervation: results of a single-center cohort study.

PURPOSE: To investigate the effect of renal denervation on office-based and 24-h ambulatory blood pressure measurements (ABPM) in a highly selective patient population with drug-resistant hypertension. MATERIALS AND METHODS: Patients with drug resistant hypertension eligible for renal denervation were included in the study population. Office blood pressure and ABPM were assessed prior to and after renal denervation. To detect procedure related renal or renal artery damage, magnetic resonance imaging (MRI) and angiography (MRA) were performed pre-interventional, one day post-interventional, and one month after renal denervation. RESULTS: Mean follow-up time between renal denervation and blood pressure re-assessment was 9.5 ±â€Š3.9 months. Between August 2011 and March 2013, 17 patients prospectively underwent renal denervation. Pre-interventional mean office blood pressure and ABPM were 177.3 ±â€Š20.3/103.8 ±â€Š20.4 mmHg and 155.2 ±â€Š20.5/93.7 ±â€Š14.5 mmHg, respectively. Post-interventional, office blood pressure was significantly reduced to 144.7 ±â€Š14.9/89.5 ±â€Š12.1 (p < 0.05). ABPM values remained unchanged (147.9 ±â€Š20.3/90.3 ±â€Š15.6, p > 0.05). The number of prescribed antihypertensive drugs was unchanged after renal denervation (4.7 ±â€Š2.0 vs. 4.2 ±â€Š1.2, p = 0.18). No renovascular complications were detected in follow-up MRI. CONCLUSION: After renal denervation, no significant decrease in ABPM was observed. These results may indicate a limited impact of renal denervation for drug resistant hypertension. KEY POINTS: • Renal denervation showed no significant effects on 24-h ambulatory blood pressure measurements. • A significant decrease in office blood pressure measurements may be explained by a potential detection bias. • Renal artery alterations were not observed on follow-up MRI scans.

The role of prostaglandins in diabetes insipidus produced by desoxycorticosterone in the dog.

To determine the role of renal prostaglandins (PGs) in the renal response to desoxycorticosterone acetate (DOCA), dogs were studied on a constant diet in which sodium intake was restricted (2.5 meq/day) or high (115 meq/day). On the restricted sodium intake, DOCA (25 mg/day im for 6 days) did not affect urinary volume, sodium, potassium, PGE2, or PGF2 alpha. On the high sodium intake, DOCA produced sodium retention for 1 day and a sustained increase in urinary potassium with a fall in serum potassium to 3.1 meq/liter. Urine volume increased from 574 +/- 50 to 1726 +/- 177 ml/day (P less than 0.001) with a fall in urinary osmolality from 1545 +/- 122 to 495 +/- 55 mosmol/ liter (P less than 0.001) as serum sodium increased from 149.0 +/- 1.0 to 152.5 +/- 0.3 meq/liter (P less than 0.025) by the sixth day of DOCA. Urinary PGE2 and PGF2 alpha were unchanged during the first 2 days of DOCA, then increased progressively from control values of 261 +/- 60 and 1143 +/- 144 ng/day ng/day, respectively, to 730 +/- 62 (P less than 0.005) and 3013 +/- 479 ng/day (P less than 0.01), respectively. Potassium repletion during continued DOCA treatment restored urinary volume, osmolality, PGE2 and PGF2 alpha, and serum sodium to control values. Treatment with indomethacin during DOCA-induced hypokalemia, polyuria, hypernatremia, and increased urinary PG, restored urinary PGs to control values, and corrected the polyuria and hypernatremia without a change in serum potassium. Thus, DOCA produced potassium depletion, polyuria, increased urinary PGs, and hypernatremia in dogs on a high sodium intake but not in those on a restricted sodium intake. As polyuria and hypernatremia were corrected either by potassium repletion, which corrected the supranormal renal synthesis of PGs, or by indomethacin, which inhibited their synthesis, renal water loss was presumably the result of an increase in renal PG synthesis, probably stimulated by potassium depletion.

Sodium-proton exchange and primary hypertension. An update.

An enhancement of sodium-proton exchange in blood cells of patients with primary hypertension has been described by various investigators. The present review summarizes some of the most recent findings regarding the enhanced sodium-proton exchanger activity in primary hypertension and discusses the potential mechanisms that may contribute to or explain these findings. Novel evidence has been accumulated on the in vivo regulation of the sodium-proton exchanger in humans, and recent findings suggest that metabolic acidosis, high NaCl intake, and circulating hormones (eg, insulin) can enhance sodium-proton exchanger activity in blood cells. However, the relative roles of such exogenous factors in the stimulation of sodium-proton exchanger activity in primary hypertension remain questionable because enhanced sodium-proton exchanger activity persists in immortalized lymphoblasts from patients with primary hypertension after prolonged cell culture. Therefore, at least in a certain group of hypertensive subjects this abnormality cannot be due to metabolic or hormonal alterations of the "hypertensive" in vivo milieu but appears to be under genetic control. Available evidence strongly argues against intrinsic changes of the sodium-proton exchanger protein itself in primary hypertension, for example, a mutation in the encoding gene. Interestingly, immortalized cells from hypertensive subjects with enhanced sodium-proton exchanger activity display a distinctly enhanced proliferation pattern that appears to be independent of this ion transport. At present we speculate that enhanced sodium-proton exchanger activity and proliferation may represent indicators of a genetically fixed enhanced intracellular signal transduction in primary hypertension that may be caused by an increased activation of pertussis toxin-sensitive G proteins.

Membrane sodium-proton exchange and primary hypertension.

Recent studies have revealed that an enhancement of sodium-proton exchange is a frequently observed ion transport abnormality in essential hypertension. An altered antiport activity not only is measurable in blood cells of hypertensive subjects ex vivo but also is detectable in skeletal muscle in vivo. Several lines of argument suggest that the altered antiport activity is not an epiphenomenon of hypertension: 1) the increased activity is found only in a subgroup of patients with high blood pressure, 2) it is not tightly correlated to the severity or duration of hypertension, and 3) high sodium-proton exchange activity persists over time and is not affected by antihypertensive treatment. Available evidence suggests that enhanced sodium-proton exchange is associated with or a cause for the structural alterations found in resistance vessels of hypertensive individuals (media hypertrophy) and left ventricular hypertrophy. This review summarizes some of the physiological properties and roles of the sodium-proton exchanger and discusses its kinetic properties in essential hypertension. Furthermore, the reasons for the enhanced antiport activity and its potential implications regarding the pathogenesis of hypertension are discussed.

Thromboxane A2 and vascular smooth muscle cell proliferation.

In the present study we describe the intracellular pathways for the transmission of growth signals by the potent vasoconstricting eicosanoids prostaglandin H2 and thromboxane A2 in smooth muscle cells from rat aorta. Carbocyclic thromboxane A2 and U46619 are stable thromboxane A2 mimetics acting at the common thromboxane A2/prostaglandin H2 receptor. Carbocyclic thromboxane A2 (10(-6) mol/L) induced an approximately 2.5-fold increase in [Ca2+]i above the basal value at 25 seconds. Maximal stimulation of the 42-kD mitogen-activated protein kinase isoform by both thromboxane A2 mimetics occurred at 5 minutes. Both thromboxane A2 mimetics at a concentration of 10(-6) mol/L induced the expression of c-fos and early growth response gene-1 (egr-1) mRNA, with a maximum at 30 minutes. Carbocyclic thromboxane A2 (10(-6) mol/L) induced a 3.3-fold increase in [3H]thymidine incorporation into cell DNA above the basal value and produced a 3.5-fold elevation of platelet-derived growth factor-BB-dependent [3H]thymidine incorporation into cell DNA. Similar effects of U46619 (10(-6) to 10(-5) mol/L) alone did in combination with platelet-derived growth factor-BB on cell DNA synthesis were obtained. The thromboxane A2/prostaglandin H2 receptor antagonist SQ29548 (10(-6) mol/L) completely suppressed the mitogenic effect of both thromboxane A2 mimetics (10(-6) mol/L). Pertussis toxin (10 to 100 ng/mL) did not influence the mitogenic effects of the thromboxane A2 mimetics. Carbocyclic thromboxane A2 (10(-6) mol/L) and platelet-derived growth factor-BB (20 ng/mL) per ser caused a 44% and 100% increase in cell number, respectively. In the presence of carbocyclic thromboxane A2 (10(-6) mol/L), platelet-derived growth factor-BB induced a 152% increase in cell number. Similar results were obtained with U46619 alone or in combination with platelet-derived growth factor-BB.

Lysophosphatidic acid and intracellular signalling in vascular smooth muscle cells.

Growth of vascular smooth muscle cells (VSMC) plays an important role in the pathogenesis of atherosclerosis and hypertension. Lysophosphatidic acid (LPA), a natural phospholipid is thought to be an important VSMC mitogen and has recently been suggested to play an important role in the development of vascular disease. In the present study, we describe the effects of LPA on intracellular signalling pathways in VSMC. LPA (5 micrograms/ml) induced an increase of cytosolic free calcium concentration ([Ca2+]i) in the presence and absence of extracellular Ca2+ and markedly stimulated the Na+/H+ exchanger. LPA dose-dependently caused a stimulation of the 42-kDa mitogen-activated protein kinase (MAP kinase) isoform with a maximum at 5 min. Also, LPA induced a 5-fold increase in [3H]thymidine incorporation into cell DNA above the basal value, as well as a 42% increase in cell number. Pretreatment of VSMC with pertussis toxin (PTX) (100 ng/ml) for 24 h markedly blunted the LPA-dependent intracellular signalling transduction including the increase in [Ca2+]i, activation of the Na+/H+ exchanger, activation of MAP kinase and the increase in cell DNA synthesis. These findings demonstrate that the effects of LPA on intracellular signalling transduction pathway as well as on VSMC growth are mediated by PTX-sensitive guanosine triphosphate (GTP) binding protein (Gi protein).

Clinical experience with strontium-89 in prostatic and breast cancer patients.

Bone metastases are a major problem in the clinical management of patients with breast or prostate cancer. Severe bone pain can be a particularly debilitating effect of metastatic disease, resulting in a growing dependency on opioid analgesics and a reduced quality of life in patients who have a short time to survive. The radiopharmaceutical strontium-89 has been demonstrated to be generally well tolerated as well as effective in reducing metastatic bone pain in breast or prostate cancer patients. Unlike other radioisotopes or external radiation treatments, it represents systemic, targeted therapy that is simple and fast to administer in an outpatient setting. Data accumulated over the last 15 years demonstrates that 89Sr provides pain relief in up to 80% of patients with bony metastases arising from breast or prostatic malignancies. Pain palliation is maintained for several months, along with improvements in functional status and quality of life. As many as one fifth of 89Sr-treated patients become pain free and require no further pain medication. The adverse effects of intravenous 89Sr are minimal. Bone marrow toxicity is observed in many patients, resulting in some reduction of platelet and white blood cell counts. Despite reductions of 20% to 30%, these hematologic effects are generally reversible and the majority of patients maintain platelet counts that are within normal limits. Strontium-89 is effective systemic radioisotopic therapy for the palliation of painful bony metastases from breast and prostate carcinoma.

The role of the prostaglandin system in the regulation of renal function in normal women.

The role of prostaglandins in the regulation of renal function was studied in seven healthy female volunteers taking a constant metabolic diet containing 59 meq of sodium and about 50 meq of potassium daily. Each subject underwent two renal clearance studies, during which vasopressin (priming dose, 200 mU; "sustainer," 200 mU/hour at 1 ml/min) was infused intravenously. The first clearance study served as the control; indomethacin (2 mg/kg/day) was given for seven days before the second clearance study to inhibit prostaglandin synthesis. Food and fluid were withheld for 12 hours before the studies. Urine was collected through an indwelling bladder catheter at 30 minute intervals. Glomerular filtration rate was estimated from inulin clearance and renal blood flow from para-aminohippurate (PAH) clearance. Indomethacin was associated with a significant increase in maximal urinary osmolality from 826 +/- 47 mosmol/kg H2) to 920 +/- 32 mosmol/kg H2O (P < 0.01). Minimal "free water" clearance was -1.40 +/- 0.02 ml/min before and -1.63 +/- 0.04 ml/min (P < 0.01) after the administration of indomethacin. Indomethacin did not affect urine flow, urinary sodium or potassium excretion, glomerular filtration rate or renal plasma flow. In addition, indomethacin did not affect the urinary excretion of cyclic adenosine monophosphate (AMP). Plasma arginine-vasopressin, measured in two subjects by radioimmunoassay, did not change with blockade of prostaglandin synthesis. It appears that prostaglandins antagonize the hydro-osmotic effect of antidiuretic hormone by an intrarenal mechanism, independent of changes in renal hemodynamics or cation excretion. This mechanism is probably mediated by an alteration in the water permeability of the collecting ducts. Since urinary cyclic AMP did not change during blockade of prostaglandin synthesis, whereas urinary osmolality increased, a change of vasopressin-dependent cyclic AMP production in the kidney was probably not reflected in urinary cyclic AMP.

Effects of valproate derivatives I. Antiepileptic efficacy of amides, structural analogs and esters.

Derivatives of the antiepileptic drug valproate (VPA, 2-propylpentanoic acid) have been synthesized and tested in order to improve the intracellular availability of VPA. The buccal ganglia of Helix pomatia were used as a test nervous system and antiepileptic efficacies were reconfirmed using rat cortex in vivo. Epileptiform activities consisted of typical paroxysmal depolarization shifts (PDS) which appeared in the identified neuron B3 with application of pentylenetetrazol. Epileptiform activities were found to be accelerated, unaffected or blocked. (i) The Amide-derivatives 2-propylpentanamide and N,N-dipropyl-2-propylpentanamide, and short chain ester derivatives 1-O-(2-propylpentanoyl)-2,3-propandiol, 2,2-di(hydroxymethyl)-1-O-(2-propylpentanoyl)-1,3-propanediol and 2,2-di(hydroxymethyl)-1,3-di-O-(2-propylpentanoyl)-1,3-propanediol accelerated epileptiform activities. Membrane potential often shifted to a permanent depolarization which corresponded to the PDS-inactivation level. (ii) The structural analogs 1-cycloheptene-1-carboxylic acid and cyclooctanecarboxylic acid accelerated epileptiform activities only slightly or were without effects. (iii) The small VPA-ester, 2-propylpentanoic acid ethyl ester, decreased the epileptiform activities in a way that is comparable to the effects of VPA well known from previous studies. It thus could be thought as a VPA-pro-drug. (iv) The mannitol-esters 1-O-(2-propylpentanoyl)-D-mannitol and 3,4;5,6-Di-O-isopropylidene-1-O-(2-propylpentanoyl)-D-mannitol blocked the PDS in a way which is different from the known effects of VPA. These substances are interpreted not to exert their effects after being metabolized to VPA and thus they are thought to be new antiepileptic substances.

Effects of valproate derivatives II. Antiepileptic efficacy in relation to chemical structures of valproate sugar esters.

The structure effect relationships of derivatives of the antiepileptically active ester of valproate (VPA) 3,4:5,6-Di-O-isopropylidene-1-O-(2-propylpentanoyl)-D-mannitol (1) have been studied using intracellular recording to record the membrane potential of single neurons (buccal ganglia, Helix pomatia). Epileptiform activity was induced by the epileptogenic drug pentylenetetrazol. The effects of several derivatives on epileptiform activity were compared with those of the relay compound 1. Most of the synthesized agents decreased the duration of paroxysmal depolarization shifts (PDS) and increased their repetition rate. It was considered that a decreased the duration of PDS is antiepileptic and an increased repetition rate is pro-epileptic. Compared with the effects of compound 1, the following relationships were found: (1) Derivatives containing glucitol or galactitol were of similar antiepileptic potency. (2) Introduction of pyranoses or furanoses rendered the substances inactive or even pro-epileptic. (3) VPA in position 1 and 6 at the sugar acted as an antiepileptic whereas in position 3 and 4 it proved to be ineffective. (4) Replacement of VPA by ethylhexanoyl reduced the antiepileptic potency slightly and pivaloyl strongly. (5) Replacement of isopropylidene bridges by penta-O-acetyl or cyclohexylidene residues led to largely inactive substances. (6) Compounds having isopropylidene bridges in position 2,4;3,5 proved to be antiepileptic whereas bridges especially in positions 2,3:4,5 slightly enhanced epileptic activities.

Platelet Na(+)-H+ exchanger activity in normotensive and hypertensive subjects: effect of enalapril therapy upon antiport activity.

OBJECTIVE: Primary hypertension has been reported to be associated with an enhancement of Na(+)-H+ exchange. However, details of the kinetic properties of the Na(+)-H+ exchanger in hypertensives and its dependence upon age and gender in normotensives are unknown. PARTICIPANTS: We determined the activity of the platelet Na(+)-H+ exchanger in 20 normotensives and 26 untreated primary hypertensives. INTERVENTIONS: In eight hypertensive individuals antihypertensive treatment was interrupted for 1 week. Treatment for 6 weeks with a daily single dose of 10 mg enalapril decreased mean arterial pressure to 105.7 +/- 11.6 mmHg. METHODS: Platelets were loaded with the intracellular pH (pHi) indicator 2'-7'-bis-carboxyethyl-5(6)-carboxyfluorescein (BCECF) and acidified by propionic acid. Initial velocities of pH recovery were determined and used for calculation of maximum velocity (Vmax), baseline pHi and the pHi value for half maximal activation (pH0.5) of the Na(+)-H+ exchanger in each individual. RESULTS: In normotensives, Vmax averaged 0.05 +/- 0.01 dpHi/min independently of age, gender and actual diastolic blood pressure. In hypertensives, two different subgroups were defined bearing either low or high Na(+)-H+ exchange activity. Values of pHi and pH0.5 were identical in all subgroups irrespective of Vmax. The twofold enhancement of Na(+)-H+ exchange in the second group was preserved in thrombin-stimulated platelets. Vmax values remained unaffected by enalapril treatment. CONCLUSIONS: Enhanced Na(+)-H+ exchange activity in hypertensives is primarily characterized by an increase in Vmax. This enhancement is refractory to antihypertensive treatment and therefore appears to be a relatively fixed parameter.

The effect of angiotensin II on DNA synthesis varies considerably in vascular smooth muscle cells from different Wistar-Kyoto rats.

OBJECTIVE: It is well established that angiotensin II induces vascular smooth muscle cell (VSMC) growth but conflicting data exist concerning whether angiotensin II induces cell hypertrophy and/or DNA synthesis from Wistar-Kyoto (WKY) rats. DESIGN: In this study we examined the effect of 10(-7) mol/l angiotensin II on cell protein and DNA synthesis in VSMC (passages 5-30) derived from eight different WKY rats. METHODS: The mitogenic and hypertrophic effect of angiotensin II was determined by 3H-thymidine incorporation into cell DNA and by total cellular protein measurements. RESULTS: In cells derived from two cell lines, angiotensin II induced a potent mitogenic effect. In cells derived from two other cell lines it induced a weak mitogenic effect. No significant effects on DNA synthesis were observed in cells derived from the four remaining cell lines. Cells from all cell lines reacted to angiotensin II with a 30-40% increase in cell protein. The observed mitogenic effect of angiotensin II was inhibited by losartan, a non-peptide angiotensin II receptor antagonist, proving that the angiotensin II-induced mitogenic effect is directly triggered via the angiotensin II subtype AT1 receptor. The hypertrophic effect of angiotensin II was also illustrated by morphological studies showing that angiotensin II increases the cell size in all cell lines used. CONCLUSIONS: Our study shows that angiotensin II not only is a hypertrophic agent, but may also be a potent mitogenic agent for VSMC from WKY rats.

Action of dihydropyridine calcium antagonists on early growth response gene expression and cell growth in vascular smooth muscle cells.

OBJECTIVE: Evidence suggests that calcium antagonists may suppress vascular smooth muscle cell (VSMC) growth and proliferation, which may be a crucial step in the pathogenesis of hypertension and atherosclerosis. DESIGN: The effects of the dihydropyridine calcium antagonists nifedipine, nitrendipine, nisoldipine, nimodipine and isradipine on cell growth induced by platelet-derived growth factor (PDGF)-AB and angiotensin II (Ang II), and expression of the transcription factors c-fos and early-growth response gene 1 (egr-1) were investigated. METHODS: Proliferation of VSMC in culture was measured by [3H]-thymidine incorporation into cell DNA and by cell count. Expression of c-fos and egr-1 messenger RNA (mRNA) was determined by the Northern blot technique. RESULTS: All of the calcium antagonists blunted the PDGF-induced rise in VSMC DNA synthesis. The inhibitory potency of isradipine on PDGF-stimulated DNA synthesis was approximately 10-fold that of the other calcium antagonists used, isradipine having a half-maximal inhibitory concentration (IC50) of (4.2 +/- 0.16) x 10(-7) mol/l. The calcium antagonists investigated also inhibited Ang II-induced DNA synthesis. Isradipine (10(-6) mol/l) completely abolished the PDGF-induced cell proliferation. Both PDGF (50 ng/ml) and Ang II (10(-7) mol/l) induced c-fos and egr-1 mRNA expression, having maximum effect after 30 min. In the case of c-fos, pre-incubation with 5 x 10(-6) mol/l isradipine led to a decrease in both Ang II- and PDGF-induced expression of this immediate-early gene. The expression of egr-1 was not affected by pre-incubation with 5 x 10(-6) mol/l isradipine. CONCLUSIONS: All calcium antagonists investigated in the present study inhibited cell growth. Isradipine was more potent in blocking growth factor-induced cell growth than the other calcium antagonists studied. The inhibitory effect of the dihydropyridine calcium antagonists appears to be dependent on the expression of c-fos.

EXP3174, a metabolite of losartan (MK 954, DuP 753) is more potent than losartan in blocking the angiotensin II-induced responses in vascular smooth muscle cells.

OBJECTIVE: EXP3174 is a metabolite of losartan (previous name DuP753), which is a non-peptide angiotensin II receptor antagonist. DESIGN: The inhibitory potency of these two antagonists on the angiotensin II-induced responses in vascular smooth muscle cells (VSMC) was investigated. METHODS: The effect of angiotensin II on cell growth was determined by [3H]-thymidine incorporation into cell DNA and by cellular protein measurements. Intracellular cytosolic Ca2+ concentration was measured by the fura-2 method. Inositolphosphates were determined by high-performance liquid chromatography after cell labelling with myo-[2-3H]-inositol. The early growth response gene-1 (Egr-1) messenger RNA (mRNA) expression was determined by the Northern blotting method. Binding and displacement studies of the antagonists were performed using [125I]-angiotensin II. RESULTS: An apparent dissociation constant (Kd) of 5.9 nmol/l for [125I]-angiotensin II (maximal binding coefficient 69 fmol/10(6) cells) was found. The specific binding of [125I]-angiotensin II to VSMC was inhibited by losartan, EXP3174 and saralasin with a half-maximal inhibitory concentration (IC50) of 1.0 X 10(-8), 1.1 X 10(-9) and 1.8 X 10(-9) mol/l, respectively. EXP3174 and losartan abolished the angiotensin II-induced formation of inositolphosphates in VSMC. EXP3174 and losartan inhibited the angiotensin II-induced elevation of intracellular cytosolic Ca2+ concentration with an IC50 of 5 X 10(-9) and 5 X 10(-8) mol/l, respectively. EXP3174 was more effective than losartan in blocking the angiotensin II-induced increase in Egr-1 mRNA. EXP3174 and losartan inhibited the angiotensin II-induced cell protein synthesis with an IC50 of 3 X 10(-9) and 4 X 10(-8) mol/l, respectively. CONCLUSIONS: These results indicate that EXP3174 is significantly more potent than losartan in blocking angiotensin II-induced cellular responses.

Combined treatment of severe essential hypertension with the new angiotensin converting enzyme inhibitor ramipril.

Ramipril is a newly synthesized angiotensin converting enzyme inhibitor without a sulfhydryl group in the molecule but with a prolonged duration of action. Efficacy, tolerance and safety of this drug were evaluated in 10 patients with severe essential hypertension. After a treatment period of at least 4 weeks with the conventional antihypertensive drug combination of a diuretic and a beta-blocking agent with the vasodilator dihydralazine, their systolic and diastolic blood pressures averaged 161 +/- 6 and 111 +/- 2 mm Hg, respectively. Because diastolic blood pressure during this drug regimen was still greater than 105 mm Hg in all patients, the patients received ramipril initially at single daily doses of 5 mg in addition to their previous medication. The first dose of 5 mg ramipril resulted in a moderate but significant decrease in systolic and diastolic blood pressure in 9 of the 10 patients to 142 +/- 5 and 104 +/- 4 mm Hg (p less than 0.01), respectively, between 3 and 6 hours after drug administration. In 1 patient blood pressure was unresponsive to ramipril and 1 patient complained of nausea and vomiting within the first week of treatment with ramipril. Within the following 8-week treatment period with a once-daily intake of 5 or, if necessary, 10 mg of ramipril, diastolic blood pressure normalized in the remaining 8 patients to less than 90 mm Hg. Systolic and diastolic blood pressure averaged 130 +/- 5 and 83 +/- 2 mm Hg, respectively, at the end of the 8-week treatment period with ramipril. Severe hypotension and reflex tachycardia were not observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Baroreflex setting and sensitivity in normal subjects: effects of pharmacologic inhibition of the angiotensin I converting enzyme.

Arterial blood pressure, heart rate and the response of these hemodynamic parameters to exogenous norepinephrine were investigated in healthy volunteers (daily sodium intake of 150 mmol) during a control period and after a single oral dose of 5 mg of the angiotensin I converting enzyme (ACE) inhibitor ramipril (HOE 498). Norepinephrine was infused at doses of 0.1, 0.2 and 0.3 micrograms kg-1 min-1, each for 10 minutes, during control and 3 hours after ramipril administration. Exogenous norepinephrine induced a dose-dependent increase in mean arterial blood pressure from 76.4 +/- 0.9 mm Hg during control to 85.6 +/- 1.5, 92.2 +/- 1.8 and 98.4 +/- 2.4 mm Hg, respectively. Ramipril significantly affected the baroreceptor set point with a decrease in mean blood pressure (72.1 +/- 1.7 vs 76.4 +/- 0.9 mm Hg, p less than 0.01) in the presence of unchanged heart rate (71.7 +/- 0.9 vs 73.6 +/- 1.5 min-1). Baroreceptor sensitivity, estimated by the slope of the delta blood pressure versus delta heart rate relation, was not affected by ACE inhibition. Also, the pressor effect of exogenous norepinephrine was unchanged by converting enzyme inhibition. The present results show that ACE inhibition with ramipril in sodium-replete healthy volunteers induces a decrease in blood pressure that is not accompanied by changes in heart rate, pressor sensitivity to exogenous norepinephrine or baroreceptor sensitivity.