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Query: UMLS:C0085580 (essential hypertension)
 14,686 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In arterial hypertension, hyperviscosity with hemorheological disturbances and platelet dysfunction may play a role in the prognosis and complications of the disease. We studied the effects of Nicardipine (NIC) on these blood disturbances in a group of 21 untreated patients with essential hypertension, aged 25 to 70 years (SBP/DBP = 185 +/- 28/105 +/- 17 mmHg). During one hour before and 4 hours after the IV injection of single doses of 5, 7.5 or 10 mg NIC over 5 min, blood pressure was recorded automatically (Dinamap). Hemorheological variables and platelet function were studied before and 30 min, 3 h and 24 hours after the injection. NIC lowered blood pressure and increased heart rate significantly (At 5 min, SBP = -24 mmHg; DBP = -18 mmHg; HR = +22 b/min). These effects were dose-dependent with rapid onset and short duration (less than 2 hrs). NIC decreased plasma viscosity from 1.36 +/- 0.08 to 1.30 +/- 0.07 Cst; p less than 0.01, whole blood viscosity from 22.4 +/- 2.8 to 20.7 +/- 1.5 mPas; p less than 0.05 for gamma = 0.512 s-1, and erythrocyte filterability with the Ca++ ionophore A 23187 from 16.3 +/- 3.8 to 13.5 +/- 3.1; p less than 0.01. Platelet aggregation with ADP was unchanged, but aggregation with A 23187 decreased from 46.9 +/- 21.2 to 31.3 +/- 25.6; p less than 0.05, as well as plasma levels of beta-thromboglobulin (71.2 +/- 29.8 to 55.4 +/- 24.3 ng/ml; p less than 0.02) and platelet generated malonaldehyde (7.2 +/- 1.8 to 6.7 +/- 1.4 nM/10(9) platelets; NS).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Effects of intravenous nicardipine on blood pressure, hemorheology platelet function in arterial hypertension. Dose-effect relations]. 311 84

The present study was undertaken to evaluate the effects of intravenous infusion of small amounts of epinephrine on haemodynamics, renal electrolyte excretion and blood platelets in essential hypertension. Arterial plasma epinephrine concentrations were increased during the infusion to approximately 2.5 nmol/l both in a group of 40-year-old men with untreated mild essential hypertension (blood pressure 154 +/- 3/100 +/- 3 mmHg, n = 12) and in a group of age-matched male controls (124 +/- 3/78 +/- 2 mmHg, n = 11). In the hypertensive group only, mean blood pressure decreased, forearm blood flow increased, forearm vascular resistance decreased (P less than 0.001 for all) and the urinary excretion of sodium and potassium increased (P less than 0.01 for both). The hypertensive group also responded with an increase in plasma beta-thromboglobulin (P less than 0.05), blood platelet size (P less than 0.05) and a higher increase in platelet counts than in the normotensive group (P less than 0.05). Thus, in several ways the hypertensive patients showed a hyper-responsiveness to amounts of epinephrine which corresponds well to the plasma concentration achieved during psychological and physical activity.
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PMID:Hyper-responsiveness to low-dose epinephrine infusion in mild essential hypertension. 324 Dec 57

Urinary concentrations of the platelet-specific protein beta-thromboglobulin (beta-TG) were measured in patients with essential hypertension. Values obtained for patients with normal renal function fell within the same population as those for a control group of normal individuals, but nevertheless 21% of these patients had urinary beta-TG values above the upper limit of the normal range. Values for patients with renal insufficiency were significantly different from the other groups, and 44% of these individuals had abnormally elevated urinary beta-TG concentrations. These elevated values may reflect an increased plasma concentration of beta-TG in patients with renal impairment or they could be an indicator of renal damage.
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PMID:Urinary beta-thromboglobulin in essential hypertension. 615 34

Twenty-three 50-year-old men with untreated, essential hypertension had elevated plasma concentrations of the platelet release product beta-thromboglobulin (BTG) compared to 14 age-matched control men (p less than 0.01). BTG correlated with arterial plasma adrenaline concentrations in the hypertensive (r = 0.44, p less than 0.05), normotensive (r = 0.73, p less than 0.01) and combined group (r = 0.51, p less than 0.01). Significant correlations (p less than 0.05) between BTG and cholesterol (LDL + VLDL fraction) were observed both in the hypertensive and the normotensive group. In the hypertensive group arterial adrenaline correlated with cholesterol (LDL + VLDL) (p less than 0.05). These findings are consistent with increased platelet activity in middle-aged men with essential hypertension, and may indicate that plasma adrenaline influence platelet function. The risk factors for coronary artery disease (blood pressure, lipid status, stress as evidenced by catecholamine release and platelet function) were positively related. Measurement of arterial instead of venous adrenaline is essential for the demonstration of the associations presented.
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PMID:Increased beta-thromboglobulin in essential hypertension: interactions between arterial plasma adrenaline, platelet function and blood lipids. 619 89

In 22 untreated patients with uncomplicated essential hypertension and in 10 normotensive subjects the plasma levels of thrombomodulin (TM), beta-thromboglobulin (beta-TG), D-dimer (DD), tissue-type plasminogen activator (t-PA) and plasminogen activator-inhibitor (PAI-1) were evaluated. The observed values show no significant difference in plasma TM, plasma and urine beta-TG concentration and plasma DD among hypertensive patients and controls. On the other hand, the levels of t-PA and PAI-1 in hypertensive patients were significantly higher than the values detected in normotensive control subjects. These data seem to indicate that, at initial stages of essential hypertension, the t-PA and PAI-1 levels increase.
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PMID:Haemostatic variables in arterial hypertension. 748 62

Twenty non-smoking middle-aged men with mild untreated essential hypertension were compared to age-matched controls (n = 22) in a double-blind placebo controlled study. Plasma and urinary concentrations of the platelet-specific protein beta-thromboglobulin (beta-TG), platelet count and mean platelet volume were measured before and after chewing 2 mg nicotine gum. The mean plasma nicotine concentration increased to 4.3 ng/ml in the hypertensive group and to 3.9 ng/ml in the normotensive group after 30 minutes of chewing the nicotine gum. Blood pressure and heart rate increased significantly, but there was no difference between the groups. Venous plasma catecholamine concentrations were unchanged. beta-TG concentrations in plasma and urine were similar in the two groups, and plasma beta-TG levels did not change after nicotine gum in either group. Urinary high molecular weight beta-TG decreased after nicotine compared to placebo. Platelet count and volume increased significantly in the hypertensive group, but not in the normotensive group. The response in platelet count was significantly higher in the hypertensive group. Thus, small amounts of nicotine increase platelet counts more in hypertensive than in normotensive non-smoking men, without inducing the platelet release reaction.
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PMID:Acute effects of low dose nicotine gum on platelet function in non-smoking hypertensive and normotensive men. 772 Jul 62

The objective of this double-blind study was: 1) to evaluate and compare the effects of treatment with two dihydropyridines--isradipine and nitrendipine--on basal and circadian blood pressure and on 24-h platelet activity; and 2) to investigate the influence of low-dose aspirin on the antihypertensive, antiplatelet (antiaggregatory) efficacy of dihydropyridines. After a 4-week placebo period, 39 patients with mild-to-moderate essential hypertension were treated for 8 weeks, according to a double-blind design, with either isradipine at 2.5 mg/day (n = 20) or nitrendipine at 10 mg/day (n = 19). After this treatment period, aspirin at 100 mg/day was added to both treatments for a further 8 weeks. At week 0 (after placebo), week 8 (after dihydropyridines), and week 16 (after dihydropyridines + aspirin), blood pressure, plasma levels of beta-thromboglobulin (beta-TG) and platelet aggregation induced by serotonin (5-HT) were measured six times a day (at 5:30 AM, 9:00 AM, noon, 3:30 PM, 7:00 PM, and 11:30 PM). Both isradipine and nitrendipine significantly lowered basal and circadian blood pressure with no differences in antihypertensive efficacy between them. Low doses of aspirin did not interfere with the antihypertensive efficacy of either agent. All patients exhibited increased platelet activity after the placebo period in the form of increased beta-TG levels with circadian changes. The steepest increase in beta-TG was observed during the morning hours until midday. Treatment with the dihydropyridines inhibited platelet aggregability, shifting the beta-TG curve toward lower values. Addition of aspirin to nitrendipine produced a significant decrease and flattening of the beta-TG curve, whereas the combination of aspirin and isradipine was accompanied by a partial increase in plasma beta-TG levels. In conclusion, treatment with dihydropyridines alone or in combination with low-dose aspirin can prevent circadian increases in platelet activity in patients with essential hypertension.
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PMID:Effects of dihydropyridines and their combination with aspirin on blood pressure and circadian platelet activity in patients with essential hypertension. 794 79

Platelet catecholamine content may reflect integrated plasma catecholamine concentrations over time. The present study aimed at examining sympathetic nervous system (SNS) involvement in essential hypertension by assessing platelet noradrenaline (NA) and typically beta-adrenoreceptor mediated responses to adrenaline (A) infusion as indices of sympathetic tone. Healthy white men were recruited by public advertising and screening (mean +/- SD): Hypertensives (n = 13, sitting blood pressure [BP] 153 +/- 13/106 +/- 7 mmHg, age 34 +/- 5 years, weight 83 +/- 10 kg) were compared to normotensives (n = 13, sitting BP 114 +/- 9/75 +/- 9 mmHg, age 30 +/- 6 years [n.s.], weight 82 +/- 9 kg [n.s.]). Loss of platelet granular contents (including NA) prior to analysis was minimized by studying young subjects (age range 20-40 years, minimal atherosclerosis), using arterial blood sampling, and processing blood immediately. These procedures resulted in plasma beta-thromboglobulin and platelet factor 4 levels which were not significantly different between groups. Sympathetic activation resulting from stress was minimized by not labelling subjects as either hypertensive or normotensive. Mean arterial platelet NA content was significantly higher in hypertensives (64 +/- 31 pg/mg of platelet weight) compared to normotensives (43 +/- 20 pg/mg, p < 0.05) both at baseline and following 35% expansion of the circulating platelet pool by A infusion (p < 0.05) and correlated with arterial NA in the hypertensives (r = 0.79, p < 0.002) but not in the normotensives (r = 0.04, n.s.). Similar increases in platelet and plasma A during infusion in both groups suggest unchanged platelet uptake capacity and plasma clearance in the hypertensive group.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Sympathetic nervous system involvement in essential hypertension: increased platelet noradrenaline coincides with decreased beta-adrenoreceptor responsiveness. 806 4

The effects of dihydropyridine calcium antagonists on blood pressure and platelets, and the effects of aspirin on the circadian antihypertensive efficacy of dihydropyridines and on the 24-h platelet-activity profile, were the focus of a double-blind study. Patients with essential hypertension were treated for 8 weeks with either isradipine focus of double-blind study. Patients with essential hypertension were treated for 8 weeks with either isradipine (2.5 mg/day) or nitrendipine (10 mg/day). Aspirin (100 mg/day) was added to both treatment groups for a further 8 weeks. Measurements were taken after 4 weeks of placebo, after 8 weeks of dihydropyridine treatment, and after 8 weeks of treatment combined with aspirin. Plasma levels of beta-thromboglobulin (beta-TG) and platelet aggregation induced by serotonin were measured six times during 24 h. Both dihydropyridines significantly lowered systolic and diastolic blood pressure. The addition of aspirin to dihydropyridine treatment had no significant effects on systolic or diastolic blood pressure. Dihydropyridine treatment lowered the increased 24-h plasma beta-TG profile and inhibited platelet aggregability. Aspirin added to nitrendipine led to a further significant decrease in beta-TG levels whereas its addition to isradipine was accompanied by a partial increase in plasma beta-TG. It is concluded that increases in platelet activity in hypertensive patients can be prevented with either isradipine alone or nitrendipine plus aspirin. Aspirin in a daily dose of 100 mg does not affect the antihypertensive efficacy of calcium antagonists.
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PMID:Treatment of hypertension with dihydropyridine calcium antagonists and aspirin. 820 3

Plasma beta-thromboglobulin (beta-TG) concentration, reflecting platelet function in vivo, was compared in fertile women with untreated essential hypertension and age-matched normotensives, in two separate studies. In the first study, hypertensives and normotensives were aware of their blood pressure status. Blood was sampled through arterial and venous indwelling catheters, and no difference in beta-TG was found between the groups. Arterial beta-TG was significantly lower than venous concentration (p < or = 0.05). Cold pressor test increased arterial beta-TG significantly in both groups (p < 0.05). In the second study, both women and investigator were unaware of blood pressure status, and beta-TG concentration, platelet count, and mean platelet volume obtained by venipunctures were similar in the hypertensive and normotensive group. Thus, platelet function in vivo seems to be normal in fertile hypertensive women, in contrast to the platelet dysfunction previously reported in hypertensive men. In women, as in men, platelet release occurred during venous catheter blood sampling and during cold pressor test. However, at variance from men, platelet function was not influenced by awareness of blood pressure status in the hypertensive females.
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PMID:Effect of cold pressor test and awareness of hypertension on platelet function in normotensive and hypertensive women. 826 4


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