Blood pressure lowering after experimental cerebral ischemia provides neurovascular protection

BACKGROUND: There is evidence that acutely elevated blood pressure (BP) after stroke is associated with increased cerebral hemorrhage and edema. Previous experiments in our laboratory have shown that candesartan 1 mg/kg administered after reperfusion in a model of hypertension after experimental ischemic stroke reduces neurovascular damage and improves outcome. These results could be either mediated by BP lowering or a BP-independent cerebrovascular protective effect. OBJECTIVES: To determine the contribution of BP lowering to the neurovascular protection previously reported with candesartan after stroke. METHODS: Male Wistar rats (280-305 g) underwent 3 h of middle cerebral artery occlusion (MCAO). At reperfusion, either hydralazine 1 mg/kg (n = 8), enalapril 5 mg/kg (n = 7) or enalapril 10 mg/kg (n = 8) were administered intravenously. BP was measured by telemetry for 2 days before and 24 h after MCAO. After neurological function was assessed, brain tissue was processed for infarct size and hemoglobin content analyses. RESULTS: Mean arterial pressure (MAP) increased from 92 to 124 mmHg immediately upon MCAO and decreased to 112 mmHg after reperfusion, remaining elevated for 24 h (P < 0.0001) in the saline group. Hydralazine reduced MAP (P = 0.048) and infarct size (53 versus 30%, P = 0.0083), and there was a trend towards decreased hemoglobin content. Enalapril 5 mg/kg did not significantly change MAP or other outcomes. Enalapril 10 mg/kg reduced MAP (P < 0.0001) and infarct size (53 versus 29%, P = 0.003). There was an intermediate effect on both hemoglobin content and neurological function, neither one was significant. The time course of BP lowering varied with each treatment. CONCLUSION: Acute BP lowering after reperfusion in acute ischemic stroke is an effective strategy to achieve neurovascular protection. The rate, extent and mechanism of BP lowering may determine the magnitude of protection.     

Comparison between early and delayed systemic treatment with candesartan of rats after ischaemic stroke

OBJECTIVE: The effects of candesartan treatment starting early (3 h) and delayed (24 h) after middle cerebral artery occlusion (MCAO) with reperfusion was investigated in normotensive rats. METHODS: Subcutaneous treatment with candesartan (0.3 and 3 mg/kg) or vehicle was initiated 3 or 24 h after the onset of MCAO and continued for seven consecutive days (n=20 per group and timepoint). Neurological outcome was evaluated daily using two different scoring systems. Infarct and oedema volumes were determined in rats 2 or 7 days after MCAO. Mean arterial, systolic and diastolic blood pressures were recorded before and after the application of candesartan. RESULTS: Mean arterial, systolic and diastolic blood pressures were markedly decreased with the high dose, but only moderately decreased with the low dose of candesartan. Vehicle-treated rats showed marked neurological deficits 24 h after MCAO, which gradually improved with time. Candesartan improved neurological outcomes at all timepoints only when treatment was started 3, but not 24 h after MCAO. The infarct volume was reduced on days 2 and 7 after MCAO in rats treated with the low but not the high dose of candesartan. CONCLUSION: The present study demonstrates that only an early but not a delayed onset of treatment with candesartan exerts neuroprotection after focal ischaemia. The degree of neurological impairments did not correlate with the infarct volume, which was reduced only after the low dose of candesartan. The high dose of candesartan failed to reduce the infarct volume, probably because of an excessive blood pressure decrease.     

坎地沙坦预处理对脑缺血再灌注大鼠血管内皮生长因子表达的影响

目的 探讨坎地沙坦预处理对脑缺血大鼠的血管保护作用.方法 48只雄性SpragurDawley大鼠,随机分为假手术组、缺血再灌注组以及坎地沙坦小剂量组[0.1 mg/(kg·d)]和大剂量组[1 mg/(kg·d)],每组12只;各组又随机分为缺血2 h后再灌注24 h和再灌注72 h亚组(每组6只).药物灌胃4周后,采用线栓法制备大脑中动脉闭塞模型,术前测量血压,分别在再灌注24 h和72 h后进行神经功能评分,然后断头取脑,采用2,3,5-氯化三苯基四氮唑染色测定脑梗死体积,通过免疫组化染色和Western印迹分析检测缺血区脑组织血管内皮生长因子(vascular endothelial growth factor,VEGF)蛋白表达.结果 坎地沙坦小剂量组和大剂量组再灌注24 h和72 h神经功能评分均显著优于缺血再灌注组(P分别为0.008和0.001),脑梗死体积显著缩小(P分别为0.010和0.000).坎地沙坦大剂量组在干预后第2周血压明显下降,小剂量组无明显降压作用.VEGF阳性表达主要分布于梗死灶周围区血管内皮细胞,其表达随时间推移进一步上调,再灌注72 h达峰值.Western印迹分析与免疫组化染色结果一致.结论 坎地沙坦可能通过上调缺血区VEGF表达缩小脑梗死体积,改善神经功能评分.     

坎地沙坦预处理对脑缺血再灌注大鼠血管内皮生长因子表达的影响

目的 探讨坎地沙坦预处理对脑缺血大鼠的血管保护作用.方法 48只雄性SpragurDawley大鼠,随机分为假手术组、缺血再灌注组以及坎地沙坦小剂量组[0.1 mg/(kg·d)]和大剂量组[1 mg/(kg·d)],每组12只;各组又随机分为缺血2 h后再灌注24 h和再灌注72 h亚组(每组6只).药物灌胃4周后,采用线栓法制备大脑中动脉闭塞模型,术前测量血压,分别在再灌注24 h和72 h后进行神经功能评分,然后断头取脑,采用2,3,5-氯化三苯基四氮唑染色测定脑梗死体积,通过免疫组化染色和Western印迹分析检测缺血区脑组织血管内皮生长因子(vascular endothelial growth factor,VEGF)蛋白表达.结果 坎地沙坦小剂量组和大剂量组再灌注24 h和72 h神经功能评分均显著优于缺血再灌注组(P分别为0.008和0.001),脑梗死体积显著缩小(P分别为0.010和0.000).坎地沙坦大剂量组在干预后第2周血压明显下降,小剂量组无明显降压作用.VEGF阳性表达主要分布于梗死灶周围区血管内皮细胞,其表达随时间推移进一步上调,再灌注72 h达峰值.Western印迹分析与免疫组化染色结果一致.结论 坎地沙坦可能通过上调缺血区VEGF表达缩小脑梗死体积,改善神经功能评分.     

Candesartan but not ramipril pretreatment improves outcome after stroke and stimulates neurotrophin BNDF/TrkB system in rats

OBJECTIVES: Drugs interfering with the renin-angiotensin system (RAS) have been shown to reduce the incidence of stroke in patients at risk and to afford neuroprotection in experimental brain ischemia. This study aimed to compare potential neuroprotective effects of systemic pretreatment with the angiotensin receptor blocker, candesartan, and the angiotensin-converting enzyme (ACE)-inhibitor, ramipril, in normotensive Wistar rats after focal cerebral ischemia, with special emphasis on the regulation of neurotrophins. METHODS: Equipotent subcutaneous doses of candesartan and ramipril were determined via inhibition of pressor responses to intravenously injected angiotensin II (Ang II) or angiotensin I (Ang I), respectively. Accordingly, animals were treated with candesartan (0.1 mg/kg body weight, twice daily), ramipril (0.01 and 0.1 mg/kg body weight, twice daily) or vehicle (0.9% saline, twice daily), respectively, 5 days prior to middle cerebral artery occlusion (MCAO) with reperfusion. Severity of stroke was estimated via infarct size [magnetic resonance imaging (MRI) 48 h after MCAO] and neurological outcome (24 h, 48 h after MCAO). Measurements of neurotrophins/receptors in brain tissue were performed 48 h after MCAO. RESULTS: Pretreatment with candesartan and ramipril (low dose) did not reduce blood pressure during MCAO, whereas ramipril high dose did. Candesartan, but not ramipril at any dose, significantly reduced stroke volume and improved neurological outcome. Poststroke mRNA and protein of the neurotrophin receptor, TrkB, were significantly elevated in animals treated with candesartan, but not ramipril. CONCLUSIONS: Systemic pretreatment with a sub-hypotensive, RAS-blocking dose of candesartan affords neuroprotection after focal ischemia, associated with increased activity of the neurotrophin BDNF/TrkB system. Ramipril at sub-hypotensive and hypotensive, RAS-blocking doses showed no significant neuroprotective effects.     

Effect of losartan versus candesartan on uric acid, renal function, and fibrinogen in patients with hypertension and hyperuricemia associated with diuretics

BACKGROUND: Hyperuricemia may counter benefits of blood pressure (BP) reduction, although this is controversial. METHODS: We examined the effects of candesartan and losartan on uric acid, creatinine, and fibrinogen. Patients with hypertension and serum uric acid > or = 0.42 mmol/L (7 mg/dL) associated with diuretics were randomized to receive losartan 50 to 100 mg or candesartan 8 to 16 mg for 24 weeks. At randomization and after 24 weeks, systolic and diastolic BP, serum uric acid, creatinine, and fibrinogen were measured. RESULTS: A total of 59 patients were entered into the study (30 in the losartan and 29 in the candesartan group). Mean systolic and diastolic BP were reduced in the candesartan group, from 156 mm Hg at baseline to 132 mm Hg at 24 weeks, and from 90.9 to 80.8 mm Hg respectively, P < .0001), and in the losartan group from 150.3 to 132 mm Hg and from 89.6 to 77.6 respectively, P < 0001). Overall mean values of fibrinogen levels were again reduced from 4.39 g/L at baseline to 4.01 g/L at 24 weeks (P < .02). Mean values of serum uric acid in the losartan and candesartan groups were similar at baseline (0.44 and 0.46 mmol/L, respectively), but they were lower in the losartan group after 24 weeks (0.39 and 0.48 mmol/L, P = .01). Twelve patients (44%) in the candesartan group had a 10% increase in serum creatinine compared with four patients (14.2%) in the losartan group (P < .02). CONCLUSIONS: Candesartan and losartan lowered BP, but only losartan reduced uric acid. The lowering of fibrinogen in both groups may explain the reduction in stroke with angiotensin receptor blockers. The effect of persistent hyperuricemia on renal function requires further study.     

Comparative effects of candesartan cilexetil and amlodipine in patients with mild systemic hypertension. Comparison of Candesartan and Amlodipine for Safety, Tolerability and Efficacy (CASTLE) Study Investigators

The comparative antihypertensive efficacy and tolerability of the angiotensin II receptor blocker candesartan cilexetil and the calcium channel blocker amlodipine were evaluated in an 8-week, multicenter, double-blind, randomized, parallel-group, forced-titration study in 251 adult patients (45% women, 16% black) with mild hypertension (stage 1). Following a 4- to 5-week placebo run-in period, patients with sitting diastolic blood pressure (BP) of 90 to 99 mm Hg received candesartan cilexetil 16 mg (n = 123) or amlodipine 5 mg (n = 128) once daily. After 4 weeks of double-blind treatment, patients were uptitrated to candesartan cilexetil 32 mg or amlodipine 10 mg once daily. There were no significant differences between the candesartan cilexetil and amlodipine regimens for reducing BP; mean systolic BP/diastolic BP reductions were -15.2/-10.2 mm Hg versus -15.4/-11.3 mm Hg, respectively (p = 0.88/0.25). Overall, 79% of patients on candesartan cilexetil and 87% of those on amlodipine were controlled (diastolic BP <90 mm Hg). A total of 3.3% of patients on candesartan cilexetil discontinued treatment, compared with 9.4% of patients on amlodipine, including 2.4% versus 4.7% for adverse events and 0% versus 1.6% for peripheral edema, respectively. Peripheral edema, the prespecified primary tolerability end point, occurred with significantly greater frequency in patients on amlodipine (22.1%; mild 8.7%, moderate 11.8%, severe 1.6%) versus patients on candesartan cilexetil (8.9%; mild 8.1%, moderate 0.8%) (p = 0.005). Candesartan cilexetil and amlodipine are both highly effective in controlling BP in patients with mild hypertension. Candesartan cilexetil offers a significant tolerability advantage with respect to less risk of developing peripheral edema.     

Lisinopril for the treatment of hypertension within the first 24 hours of acute ischemic stroke and follow-up

BACKGROUND: Hypertension immediately after acute ischemic stroke is associated with impaired morbidity and mortality, although there are few data on antihypertensive use immediately after ictus. This randomized, double-blinded, placebo-controlled, parallel-group study explored the hemodynamic effect and safety of oral lisinopril initiated within 24 h after an ictus. METHODS: Forty hypertensive (systolic blood pressure [BP] >/=140 or diastolic BP >/=90 mm Hg) acute ischemic stroke patients (14 lacunar, 13 partial anterior, 7 total anterior, 6 posterior circulation infarct) were randomized to 5 mg of oral lisinopril (n = 18) or matching placebo (n = 22). Dose was increased to 10 mg (or 2 x placebo) on day 7 if casual systolic BP was >/=140 mm Hg and continued to day 14. After the initial dose, automated BP levels were monitored for 16 h. The BP levels and stroke outcome measures were assessed at day 14, and all patients were followed to day 90. RESULTS: At h 4 after the first dose, systolic/diastolic BP change was -20 +/- 21/-6 +/- 10 mm Hg (mean +/- SE) in the lisinopril group and 1 +/- 11/0 +/- 8 mmHg in the placebo group (group differences: systolic BP, P < .05; diastolic BP, P = .07). With a daily dosing regime, systolic BP, mean arterial pressure (MAP), diastolic BP, and pulse pressure (PP) were significantly lower in the lisinopril group compared to the placebo group at day 14 (P < .01). Neurologic and functional measures were similar between groups at follow-up. CONCLUSIONS: Lisinopril, even at small dosages, is well tolerated and an effective hypotensive agent after acute ischemic stroke, gradually reducing BP by 4 h after oral first-dose administration. Oral lisinopril is now being studied in a larger outcome-based trial in acute hypertensive stroke patients.     

Chronic pretreatment with candesartan improves recovery from focal cerebral ischaemia in rats

OBJECTIVE: In the present study, we investigated whether systemic pretreatment with the AT1 receptor antagonist, candesartan, reduces neuronal injury after cerebral ischaemia in rats. DESIGN AND METHODS: Focal cerebral ischaemia in male, normotensive Wistar rats was induced by 90 min middle cerebral artery occlusion (MCAO) followed by reperfusion. Experiment 1: Candesartan was injected intravenously (i.v.) at doses of 0.1 or 0.3 mg/kg, 4 h prior to ischaemic injury. Experiment 2: Rats were treated with candesartan [0.1 mg/kg, subcutaneously (s.c.) twice daily], on 5 consecutive days prior to ischaemia. The last injection was administered 12 h before MCAO. Mean arterial pressure (MAP) was measured before, during and after ischaemic injury. Twenty-four hours after ischaemia, neurological outcome, infarct volume and brain oedema were evaluated. RESULTS: Acute i.v. pretreatment with candesartan, 0.1 and 0.3 mg/kg, dose-dependently decreased MAP before, during and after ischaemic injury but did not improve recovery from brain ischaemia. Systemic long-term s.c. pretreatment with 0.1 mg/kg candesartan, reduced MAP during and after ischaemia to the same extent as did the i.v. dose of 0.1 mg administered 4 h before MCAO, but significantly improved neurological outcome and reduced infarction size and oedema of the ipsilateral hemisphere when compared with the vehicle-treated group. CONCLUSION: Long-term blockade of AT1 receptors improves neurological outcome of focal cerebral ischaemia and protects brain tissue against ischaemic injury.     

Blood Pressure Goals in Acute Stroke—How Low Do You Go?

Purpose of Review

Elevations in systolic blood pressure (BP) greater than 140 mmHg are reported in the majority (75%) of patients with acute ischemic stroke and in 80% of patients with acute intracerebral hemorrhages (ICH). This paper summarizes and updates the current knowledge regarding the proper management strategy for elevated BP in patients with acute stroke.

Recent Findings and Summary

Recent studies have generally showed a neutral effect of BP reduction on clinical outcomes among acute ischemic stroke patients. Thus, because of the lack of convincing evidence from clinical trials, aggressive BP reduction in patients presenting with acute ischemic stroke is currently not recommended. Although in patients treated with intravenous tissue plasminogen activator, guidelines are recommending BP?<?180/105 mmHg but currently, the optimal BP management after reperfusion therapy still remains unclear. In acute ICH, the evidence from randomized clinical trials supports the immediate BP lowering targeting systolic BP to 140 mmHg, which is now recommended by guidelines.

     

Can Ischemic Stroke Be Caused by Acute Reduction of Blood Pressure in the Acute Phase of Cardiovascular Disease?

Acute-phase cardiovascular disease (CVD) frequently presents with markedly elevated blood pressure (BP) levels and often requires fairly rapid lowering of BP. On the other hand, aggressive lowering of systemic BP to the point that the cerebral BP decreases below a certain threshold may result in ischemic stroke. The authors retrospectively studied 192 consecutive patients with CVD who had markedly elevated BP and end-organ damage. Ischemic stroke was noted in 12 of these patients during BP-lowering therapy. The incidence of ischemic stroke did not differ significantly between a standard BP-lowering group, in which the target BP reduction was within the parameters of the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure guidelines, and a rapid BP-lowering group, in which the target BP was below these guidelines (7.1% vs 2.6%, respectively; P=.27, not significant). In stepwise multiple regression analysis, diabetes mellitus (beta=0.203, P=.008) and acute pulmonary edema (beta=0.228, P=.003) remained significant factors associated with the incidence of stroke. Thus, acute pulmonary edema and diabetes were the most important factors related to ischemic stroke during BP reduction in patients with marked elevations of BP regardless of the rapidity of BP lowering.     

大鼠脑缺血再灌注后肿瘤坏死因子-α与脑水肿的相关性研究

目的 探讨脑缺血再灌注后缺血脑组织肿瘤坏死因子-α(tumor necrosis factor-α,TNF-α)与脑梗死组织水肿的关系.方法 SD大鼠随机分为脑缺血再灌注组(n=44)和假手术组(n=40).应用线栓法制备大鼠大脑中动脉闭塞2 h后再灌注模型,分别在再灌注后6 h、24 h、3 d、7 d通过2,3,5-三苯基氯化四氮唑染色法确定梗死灶大小,采用干、湿重法检测脑组织水含量评价脑水肿程度,以酶联免疫吸附法测定缺血脑组织TNF-α含量.结果 缺血脑组织TNF-α含量在再灌注6 h即升高,为(445.8±91.7)pg/ml,3 d达高峰,为(715.5±121.3)pg/ml,与假手术组和其他时间点比较均有显著差异(P均＜0.001),此后逐渐下降,7 d时仍显著高于假手术组[(478.1±145.5)pg/ml对(148.5±101.7)pg/ml,P＜0.005];脑组织水含量的起始变化滞后于TNF-α含量的增高,脑缺血再灌注24 h才显著增高(P＜0.001),3 d达高峰(P＜0.001),7 d时仍高于对照组(P＜0.05);脑梗死体积演变与TNF-α水平变化一致.结论 TNF-α与大鼠脑缺血再灌注后脑水肿和梗死体积变化有关,对脑组织有损害作用.     

Alcohol‐Induced Exacerbation of Ischemic Brain Injury: Role of NAD(P)H Oxidase

Background: Chronic alcohol consumption increases ischemic stroke and exacerbates ischemic brain injury. We determined the role of NAD(P)H oxidase in exacerbated ischemic brain injury during chronic alcohol consumption. Methods: Sprague Dawley rats were fed a liquid diet with or without alcohol (6.4% v/v) for 8 weeks. We measured the effect of apocynin on 2‐hour middle cerebral artery occlusion (MCAO)/24‐hour reperfusion‐induced brain injury. In addition, superoxide production and expression of NAD(P)H oxidase subunit, gp91phox, in the peri‐infarct area were assessed. Results: Chronic alcohol consumption produced a larger infarct volume, worse neurological score, and higher superoxide production. Acute (5 mg/kg, ip, 30 minutes before MCAO) and chronic treatment with apocynin (7.5 mg/kg/d in the diet, 4 weeks prior to MCAO) reduced infarct volume, improved neurological outcome, and attenuated superoxide production in alcohol‐fed rats. Expression of gp91phox at basal conditions and following ischemia/reperfusion was greater in alcohol‐fed rats compared to non‐alcohol‐fed rats. In addition, neurons are partially responsible for upregulated gp91phox during alcohol consumption. Conclusions: Our findings suggest that NAD(P)H oxidase may play an important role in exacerbated ischemic brain injury during chronic alcohol consumption.     

Addition of manidipine improves the antiproteinuric effect of candesartan in hypertensive patients with type II diabetes and microalbuminuria

BACKGROUND: We sought to compare the effect of manidipine versus hydrochlorothiazide (HCTZ) in addition to candesartan on the urinary albumin excretion rate (UAER) in hypertensive patients with type II diabetes and microalbuminuria. METHODS: After a 2-week washout and run-in period, and 8-week monotherapy with candesartan 16 mg every day, 174 microalbuminuric diabetic hypertensive patients with uncontrolled blood pressure (BP) (>130/80 mm Hg) were randomized to addition of manidipine 10 mg every day (n = 87) or HCTZ 12.5 mg every day (n = 87) for 24 weeks, with a titration after 4 weeks (manidipine or HCTZ dose-doubling) in nonresponder patients. Blood pressure, UAER, creatinine clearance, serum electrolytes, fasting plasma glycemia, and glycosylated hemoglobin were evaluated at baseline (end of run-in period), after candesartan monotherapy, and at the end of the combination treatment period. RESULTS: Both combinations produced greater systolic BP/diastolic BP reduction than candesartan monotherapy (-28/21 mm Hg versus -16/11 mm Hg and -28/20 mm Hg versus -15/11 mm Hg, respectively; all P < .05 versus monotherapy), with no significant difference between the two combinations. The addition of manidipine produced a greater reduction in UAER than candesartan monotherapy (-55.4 mg/24 h v -36.1 mg/24 h, P < .05), whereas the addition of HCTZ did not significantly modify UAER; the difference between the two combinations was statistically significant (P < .05). Similarly, the percentage of patients moving to a normoalbuminuric state (UAER <30 mg/24 h) was increased by the addition of manidipine to candesartan (from 35% to 64%, P < .05), but not by the addition of HCTZ (from 34% to 39%, NS), with a statistical difference between the two combinations (P < .05). CONCLUSIONS: These findings show that, despite equivalent reduction in BP, the addition of manidipine to candesartan further reduced the UAER, whereas the addition of HCTZ did not modify the UAER. This suggests that the antiproteinuric effect of manidipine is partially independent of BP reduction, and is attributable to mechanisms different from those mediated by angiotensin receptor blockade.     

The effect of 24 h blood pressure levels on early neurological recovery after stroke

OBJECTIVES: To assess the influence of 24 h blood pressure (BP) levels on functional recovery 1 week after stroke and the effect of antihypertensive therapy on 24 h BP levels. DESIGN: Prospective study of patients admitted to hospital over 1 year with first in a lifetime stroke who underwent 24 h BP and casual measurements. Setting. Medical wards in a teaching hospital. Subjects. Of 160 patients, 72 patients admitted to hospital within 24 h of stroke onset were investigated. Patients with conditions and therapy that interfered with autonomic and sympathetic function were excluded. Interventions. All subjects underwent 24 h BP and casual recordings on admission to hospital and at day seven after stroke. The mean 24 h, day and night systolic BP (SBP) and diastolic BP (DBP) and their differences (nocturnal BP dip) were recorded. Patients were divided into three groups according to whether they were taking antihypertensive therapy during the first week: (i) no therapy, (ii) therapy continued after stroke, and (iii) new therapy introduced. Main outcome measures. Functional recovery (Rankin Scale 0-1) and neurological improvement [Scandinavian Stroke Scale (SSS) >/=3 points] by 1 week of stroke. Change in circadian 24 h BP over 1 week. RESULTS: For each 10 mmHg difference between day and night time DBP, the odds for making a complete recovery were 4.63 (95% CI: 1.57-13.7, P=0.01). For each 10 mmHg difference between day and night SBP, the odds for making an improvement in neurological status was 2.24 (95% CI: 1.16-4.32; P=0.016). Significant falls in 24 h DBP (P=0.01), daytime SBP (P=0.005) and mean arterial BP (MABP) (P=0.04) over 1 week were demonstrated in patients who had just commenced antihypertensive therapy (P=0.001). CONCLUSION: An increase in day to night time BP change is favourable in short-term outcome after acute stroke. Significant falls in BP are more likely in patients started on antihypertensive therapy for the first time. Further research is required to understand the effects of circadian BP rhythm on stroke outcome.     

Therapy with recombinant T-cell receptor ligand reduces infarct size and infiltrating inflammatory cells in brain after middle cerebral artery occlusion in mice

Stroke induces a biphasic effect on the peripheral immune response that involves early activation of peripheral leukocytes followed by severe immunosuppression and atrophy of the spleen. Peripheral immune cells, including T lymphocytes, migrate to the brain and exacerbate the developing infarct. Recombinant T-cell receptor (TCR) Ligand (RTL)551 is designed as a partial TCR agonist for myelin oligodendrocyte glycoprotein (MOG)-reactive T cells and has demonstrated the capacity to limit infarct volume and inflammation in brain when administered to mice undergoing middle cerebral artery occlusion (MCAO). The goal of this study was to determine if RTL551 could retain protection when given within the therapeutically relevant 4 h time window currently in clinical practice for stroke patients. RTL551 was administered subcutaneously 4 h after MCAO, with repeated doses every 24 h until the time of euthanasia. Cell numbers were assessed in the brain, blood, spleen and lymph nodes and infarct size was measured after 24 and 96 h reperfusion. RTL551 reduced infarct size in both cortex and striatum at 24 h and in cortex at 96 h after MCAO and inhibited the accumulation of inflammatory cells in brain at both time points. At 24 h post-MCAO, RTL551 reduced the frequency of the activation marker, CD44, on T-cells in blood and in the ischemic hemisphere. Moreover, RTL551 reduced expression of the chemokine receptors, CCR5 in lymph nodes and spleen, and CCR7 in the blood and lymph nodes. These data demonstrate effective treatment of experimental stroke with RTL551 within a therapeutically relevant 4 h time window through immune regulation of myelin-reactive inflammatory T-cells.     

Indapamide SR versus candesartan and amlodipine in hypertension: the X-CELLENT Study

BACKGROUND: Reducing systolic blood pressure (BP) is of major benefit to patients with isolated systolic hypertension, but lowering normal diastolic BP may be harmful in terms of cardiovascular risk. Effects of different drugs on systolic BP, diastolic BP, and pulse pressure are therefore of interest. METHODS: The NatriliX SR versus CandEsartan and amLodipine in the reduction of systoLic blood prEssure in hyperteNsive patienTs study (X-CELLENT) was a randomized, double-blind, placebo-controlled study comparing the effects of three drugs on these BP components. Patients with systolic-diastolic or isolated systolic hypertension (n = 1758) received indapamide (1.5 mg) sustained release (SR), candesartan (8 mg), amlodipine (5 mg), or placebo once daily for 12 weeks. RESULTS: Compared to placebo all active treatments reduced all BP components significantly (P < .001). For the patients with isolated systolic hypertension (n = 388), the three treatments significantly reduced systolic BP, but only indapamide SR did not change diastolic BP and thus reduced pulse pressure significantly relative to placebo (P = .005). In an ancillary study using ambulatory BP monitoring (n = 576), all three treatments significantly reduced BP components during 24 h relative to placebo. Changes in systolic BP and pulse pressure were similar with the three treatments, but the reduction in diastolic BP was significantly smaller, and therefore more favorable, with indapamide SR compared with candesartan (P = .039). In patients with isolated systolic hypertension (n = 106), indapamide SR reduced 24-h systolic BP significantly more than amlodipine (P = .037), and only indapamide SR reduced 24-h pulse pressure significantly relative to placebo (P = .03). All three drugs were well tolerated. CONCLUSIONS: This distinctive BP-lowering profile of indapamide SR seems highly beneficial when compared to the either of candesartan or amlodipine.     

Protective effect of candesartan in experimental ischemic stroke in the rat mediated by AT2 and AT4 receptors

OBJECTIVES: The contribution of the AT2 and AT4 angiotensin receptors to the protective role of the AT1 receptor blocker candesartan in acute ischemic stroke was investigated. METHODS: Embolic stroke was induced by injection of calibrated microspheres (50 microm) in the right internal carotid in Sprague-Dawley rats. RESULTS: Inhibition of production of endogenous angiotensins by pretreatment for 24 h with lisinopril significantly increased mortality and infarct volume, whereas candesartan for 24 h reduced blood pressure to the same extent but had no deleterious effect. A more sustained pretreatment with candesartan for 5 days significantly decreased mortality, neurological deficit and infarct size. The AT2 receptor antagonist PD123319 and the AT4 receptor antagonist divalinal abolished the protective effect of 5 days' AT1 blockade. Combined blockade of AT2 and AT4 in candesartan pretreated rats resulted in an increased mortality, neurological deficit and infarct volume of similar magnitude to lisinopril pretreatment. Coadministration of lisinopril 24 h before surgery completely blunted the protective effect of candesartan pretreatment. Administration of exogenous angiotensin IV (1 nmol) reversed the deleterious effect of lisinopril pretreatment. CONCLUSION: Protection against acute cerebral ischemia induced by AT1 blockade for 5 days is blood pressure independent and mediated by both AT2 and AT4 angiotensin receptors.     

Post-ischemic cardiac chamber stiffness and coronary vasomotion: the role of edema and effects of dextran

Contributions of edema to left ventricular (LV) chamber stiffness and coronary resistance after ischemia were studied in isolated buffer-perfused rabbit hearts, with constant LV chamber volume, subjected to 30 min global ischemia and 60 min reperfusion. During reperfusion hearts were perfused with standard buffer or with 3% dextran to increase oncotic pressure and decrease water content. LV chamber volume was adjusted to an initial diastolic pressure (LVEDP) of 10 mmHg. In nonischemic hearts (n = 6) LVEDP was 11 +/- 0.3 mmHg and water content was 5.0 +/- 0.1 ml/g dry weight after 90 min of perfusion. In untreated ischemic hearts (n = 8) LVEDP was 51 +/- 4 mmHg and water content was 6.0 +/- 0.1 ml/g dry weight after 60 min reperfusion (P less than 0.001 v. nonischemic). In dextran-treated ischemic hearts (n = 8) LVEDP was 38 +/- 3 mmHg (P less than 0.05 v. untreated ischemic) and water content was 5.2 +/- 0.1 ml/g dry weight (P less than 0.001 v. untreated ischemic). Coronary resistance in untreated ischemic hearts increased by 26% from 2.0 +/- 0.06 to 2.6 +/- 0.06 mmHg/ml/min after 60 min reperfusion. In treated hearts coronary resistance increased by 16% from 1.9 +/- 0.09 to 2.2 +/- 0.09 mm/Hg/ml/min (P less than 0.01 v. untreated ischemic). To determine whether the decrease in coronary resistance with dextran could be ascribed to active vasodilation, dilator responses to 2 min hypoxia or 10(-4)M adenosine were tested in nonischemic and reperfused ischemic hearts. Dilator responses were stable in nonischemic hearts or hearts reperfused after 15 min ischemia but after 30 min ischemia the dilator response to hypoxia was reduced by 72% (P less than 0.025) and the dilator response to adenosine was eliminated (P less than 0.02). Thus the response to dextran was unlike that of a direct vasodilator. These data suggest that myocardial edema plays a significant role in maintaining increased ventricular chamber stiffness and coronary resistance during reperfusion after ischemia.     

Pulse pressure lowering effect of dual blockade with candesartan and lisinopril vs. high-dose ACE inhibition in hypertensive type 2 diabetic subjects: a CALM II study post-hoc analysis

BACKGROUND: Elevated pulse pressure (PP) is strongly associated with micro- and macrovascular complications in type 2 diabetic patients. We examined the effect of 12 months of dual blockade with candesartan and lisinopril vs. high-dose lisinopril monotherapy on ambulatory PP in hypertensive type 2 diabetic patients from the CALM (Candesartan and Lisinopril Microalbuminuria Trial) II study. METHODS: The CALM II study was a 12-month prospective, randomized, parallel-group, double-masked study that included 75 type 1 and type 2 diabetic subjects with hypertension. Participants were randomized for treatment with either high-dose lisinopril (40 mg once daily (o.d.)) or for dual blockade treatment with candesartan (16 mg o.d.) and lisinopril (20 mg o.d.). In this article, we present data from the post-hoc subgroup of 51 type 2 diabetic subjects who completed the full 12-month study period with successful ambulatory blood pressure (BP) measurements at both baseline and follow-up visits. RESULTS: Baseline 24-h BP values were similar in the two groups (24-h systolic BP (SBP) 130 +/- 12 vs. 127 +/- 9, 24-h diastolic BP (DBP) 77 +/- 8 vs. 74 +/- 7, and 24-h PP 53 +/- 8 vs. 53 +/- 7 mm Hg, for the lisinopril and dual blockade groups, respectively, P > 0.2 for all). Compared with lisinopril monotherapy, dual blockade treatment caused a highly significant reduction in 24-h PP levels (-5 +/- 5 mm Hg, P = 0.003), albeit the difference in the BP lowering effect between the treatment groups did not differ significantly for 24-h systolic (P = 0.21) or diastolic (P = 0.49) BP. Dual blockade treatment significantly lowered 24-h SBP (-5 +/- 11 mm Hg, P = 0.03), but not 24-h DBP (-2 +/- 7 mm Hg, P = 0.29), whereas in the lisinopril group, the opposite effect was observed (24-h SBP -1 +/- 9 mm Hg, P = 0.45, 24-h SBP -3 +/- 7 mm Hg, P = 0.03). CONCLUSIONS: Twelve months of dual blockade with candesartan and lisinopril significantly reduced PP when compared with high-dose monotherapy with lisinopril. Larger studies are needed to confirm this observation, and to evaluate whether this effect translates into a greater degree of end-organ protection from dual blockade treatment than from conventional angiotensin-converting enzyme (ACE) inhibition.