High plasma levels of endothelin-1 and atrial natriuretic peptide in patients with acute ischemic stroke

Assessment of brain natriuretic peptide and copeptin as correlates of blood pressure in chronic hypertensive pregnant women

BACKGROUND

Hypertensive disorders of pregnancy including preexisting (or chronic) hypertension are the most common complication encountered during pregnancy that contribute significantly to maternal and perinatal morbidity and mortality. Brain natriuretic peptide (BNP) and copeptin have been investigated as biomarkers in various hypertensive disorders, but studies of their clinical value in chronic hypertensive pregnant women are sparce. This study aimed to assess the levels of BNP and copeptin in chronic hypertensive pregnant women and investigate their correlation with blood pressure (BP) in chronic hypertensive pregnant women in South Western Nigeria.

METHODS

One hundred and sixty consenting pregnant women in their third trimester of pregnancy, grouped into those with chronic hypertension (n = 80) and normotensive (n = 80), were recruited for this cross-sectional study. Age and clinical characteristics were obtained, and blood was aseptically drawn for BNP and copeptin measurement using enzyme-linked immunosorbent assay. Data was analyzed with IBM SPSS ver. 20.0. Data was analyzed using Student t-test, chi-square, and Pearson correlation test as appropriate. Statistical significance was set at P < 0.05.

RESULTS

The mean systolic BP (SBP) and diastolic BP (DBP) were significantly higher in pregnant women with chronic hypertension (158.30 ± 3.51 and 105.08 ± 2.47 mmHg, respectively) compared with normotensive pregnant women (100.72 ± 3.02 and 70.29 ± 1.96 mmHg, respectively). The mean levels of BNP and copeptin were higher in pregnant women with chronic hypertension (57.26 ± 3.65 pg/mL and 12.44 ± 1.02 pmol/L, respectively) compared with normotensive pregnant women (49.85 ± 2.44 pg/mL and 10.25 ± 1.50 pmol/L, respectively) though not statistically significant. Correlations observed between SBP and DBP with levels of BNP (r = 0.204, P = 0.200; r = 0.142, P = 0.478) and copeptin (r = - 0.058, P = 0.288; r = 0.045, P = 0.907) were not statistically significant.

CONCLUSIONS

There was no association between BP and the levels of BNP and copeptin in pregnant women with chronic hypertension who were already on antihypertensive treatment, with the implication that antihypertensive treatment may modulate BNP and copeptin release despite significantly elevated BP levels.

Role of uroguanylin's signaling pathway in the development of ischemic stroke

Stroke is one of the leading causes of mortality and disability worldwide. By affecting bradykinin function, activation of guanylate cyclase (GC)‐A has been shown to have a neuroprotective effect after ischaemic stroke, whereas the same has not been confirmed for GC‐B; therefore, we aimed to determine the possible role of GC‐C and its agonist, uroguanylin (UGN), in the development of stroke. In this study, middle cerebral artery occlusion (MCAO) was performed on wild‐type (WT), GC‐C KO and UGN KO mice. MR images were acquired before and 24 h after MCAO. On brain slices 48 h after MCAO, the Ca²⁺ response to UGN stimulation was recorded. Our results showed that the absence of GC‐C in GC‐C KO mice resulted in the development of smaller ischaemic lesions compared with WT littermates, which is an opposite effect compared with the effects of GC‐A agonists on brain lesions. WT and UGN KO animals showed a stronger Ca²⁺ response upon UGN stimulation in astrocytes of the peri‐ischaemic cerebral cortex compared with the same cortical region of the unaffected contralateral hemisphere. This stronger activation was not observed in GC‐C KO animals, which may be the reason for smaller lesion development in GC‐C KO mice. The reason why GC‐C might affect Ca²⁺ signalling in peri‐ischaemic astrocytes is that GC‐C is expressed in these cells after MCAO, whereas under normoxic conditions, it is expressed mainly in cortical neurons. Stronger activation of the Ca²⁺‐dependent signalling pathway could lead to the stronger activation of the Na⁺/H⁺ exchanger, tissue acidification and neuronal death.

Association between Lys198Asn polymorphism of endothelin-1 gene and ischemic stroke: A meta-analysis

BACKGROUND

Endothelin (ET)-1 is a potent vasoconstrictor peptide produced by endothelial cells and associated with vascular dysfunction and cardiovascular disease. Lys198Asn is a single-nucleotide polymorphism (SNP) of gene encoding ET-1 (EDN1). It is hypothesized that it might have a role in altering ET-1 and ultimately leading to vascular dysfunction and ischemic stroke. We therefore conducted a meta-analysis to investigate the association between Lys198Asn polymorphism of EDN1 gene and susceptibility of ischemic stroke.

METHODS

This meta-analysis was conducted according to the guidance of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. We searched PubMed, Google Scholar, Embase, Web of Science, J-STAGE, and China National Knowledge Infrastructure (CNKI) for relevant studies. The association between Lys198Asn polymorphism and ischemic stroke susceptibility was evaluated by calculating the pooled ORs and 95% CIs.

RESULTS

Our analysis included 1,291 cases and 2,513 controls. Meta-analysis established a significant association between Lys198Asn SNP of EDN1 gene and ischemic stroke when assuming either recessive model (OR: 1.30; 95% CI: 1.02-1.65; p = .03; I2  = 41%) or dominant model (OR: 1.48; 95% CI: 1.24-1.76; p < .001; I2  = 61%). There was no evidence of publication bias in either of the recessive model (Egger test: p = .23; Begg test: p = .85) or dominant model (Egger test: p = .79; Begg test: p = .85). A subgroup analysis based on subtypes of ischemic stroke showed that Lys198Asn SNP was only associated with large vessel infarction but not with lacunar infarction caused by small vessel disease. A subgroup analysis based on ethnicity revealed that the Lys198Asn polymorphism of the EDN1 gene was associated with ischemic stroke only in Caucasians.

CONCLUSIONS

The present meta-analysis suggests that Lys198Asn polymorphism of EDN1 gene is associated with an increased risk for ischemic stroke.

Inflammatory, regulatory, and autophagy co-expression modules and hub genes underlie the peripheral immune response to human intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) has a high morbidity and mortality. The peripheral immune system and cross-talk between peripheral blood and brain have been implicated in the ICH immune response. Thus, we delineated the gene networks associated with human ICH in the peripheral blood transcriptome. We also compared the differentially expressed genes in blood following ICH to a prior human study of perihematomal brain tissue.

METHODS

We performed peripheral blood whole-transcriptome analysis of ICH and matched vascular risk factor control subjects (n = 66). Gene co-expression network analysis identified groups of co-expressed genes (modules) associated with ICH and their most interconnected genes (hubs). Mixed-effects regression identified differentially expressed genes in ICH compared to controls.

RESULTS

Of seven ICH-associated modules, six were enriched with cell-specific genes: one neutrophil module, one neutrophil plus monocyte module, one T cell module, one Natural Killer cell module, and two erythroblast modules. The neutrophil/monocyte modules were enriched in inflammatory/immune pathways; the T cell module in T cell receptor signaling genes; and the Natural Killer cell module in genes regulating alternative splicing, epigenetic, and post-translational modifications. One erythroblast module was enriched in autophagy pathways implicated in experimental ICH, and NRF2 signaling implicated in hematoma clearance. Many hub genes or module members, such as IARS, mTOR, S1PR1, LCK, FYN, SKAP1, ITK, AMBRA1, NLRC4, IL6R, IL17RA, GAB2, MXD1, PIK3CD, NUMB, MAPK14, DDX24, EVL, TDP1, ATG3, WDFY3, GSK3B, STAT3, STX3, CSF3R, PIP4K2A, ANXA3, DGAT2, LRP10, FLOT2, ANK1, CR1, SLC4A1, and DYSF, have been implicated in neuroinflammation, cell death, transcriptional regulation, and some as experimental ICH therapeutic targets. Gene-level analysis revealed 1225 genes (FDR p < 0.05, fold-change > |1.2|) have altered expression in ICH in peripheral blood. There was significant overlap of the 1225 genes with dysregulated genes in human perihematomal brain tissue (p = 7 × 10-3). Overlapping genes were enriched for neutrophil-specific genes (p = 6.4 × 10-08) involved in interleukin, neuroinflammation, apoptosis, and PPAR signaling.

CONCLUSIONS

This study delineates key processes underlying ICH pathophysiology, complements experimental ICH findings, and the hub genes significantly expand the list of novel ICH therapeutic targets. The overlap between blood and brain gene responses underscores the importance of examining blood-brain interactions in human ICH.

Midregional pro-atrial natriuretic peptide, an important member of the natriuretic peptide family: potential role in diagnosis and prognosis of cardiovascular disease

Midregional pro-atrial natriuretic peptide (MR-proANP), first isolated in 1981, is a novel peptide with multiple biological functions, especially within the cardiovascular system. This peptide plays an important role in many processes, including natriuresis, diuresis, and other physiological and pathophysiological pathways in the human body. Several electronic databases (PubMed, EBSCO, Scopus, and ScienceDirect) were analyzed in the present literature review. The aim of this study was to elucidate the wide roles of MR-proANP, which can be analyzed because of the development of a new sandwich immunoassay, and to determine the possible diagnostic and prognostic implications of MR-proANP on cardiovascular disease and other disorders. The studies discussed in this literature review provide valuable data on the role of ANP in the pathogenesis, diagnostic process, prognosis, and potential therapeutic strategies for disease. Although ANP is mainly associated with cardiovascular disease, it may be used as a biomarker in diabetology, neurology, and metabolic disorders.

Cerebrovascular Gene Expression in Spontaneously Hypertensive Rats After Transient Middle Cerebral Artery Occlusion

Hypertension is a major risk factor for stroke, which is one of the leading global causes of death. In the search for new and effective therapeutic targets in stroke research, we need to understand the influence of hypertension in the vasculature following stroke. We used Affymetrix whole-transcriptome expression profiling as a tool to address gene expression differences between the occluded and non-occluded middle cerebral arteries (MCAs) from spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats after transient middle cerebral artery occlusion (tMCAO), to provide clues about the pathological mechanisms set in play after stroke. Verified by quantitative PCR, expression of Ccl2, Edn1, Tgfβ2, Olr1 and Serpine1 was significantly increased in the occluded compared to non-occluded MCAs from both SHRs and WKY rats. Additionally, expression of Mmp9, Icam1, Hif1α and Timp1 was increased in the occluded compared to non-occluded MCAs isolated from WKY rats. In comparison between occluded MCAs from SHRs versus occluded MCAs from WKY rats, expression of Ccl2, Olr1 and Serpine1 was significantly increased in SHR MCAs. However, the opposite was observed regarding expression of Edn1. Thus these data suggest that Ccl2, Edn1, Tgfβ2, Olr1 and Serpine1 may be possible mediators of the vascular changes in the occluded MCAs from both SHRs and WKY rats after tMCAO. The aforementioned genes possess biological functions that are consistent with early stroke injuries. In conclusion, these genes may be potential targets in future strategies for acute stroke treatments that can be used in patients with and without hypertension.

Contractile Responses in Spontaneously Hypertensive Rats after Transient Middle Cerebral Artery Occlusion

Stroke is one of the leading causes of mortality and morbidity worldwide, and few therapeutic treatments have shown beneficial effect clinically. One reason for this could be the lack of risk factors incorporated into the preclinical stroke research. We have previously demonstrated phenotypic receptor changes to be one of the injurious mechanisms occurring after stroke but mostly in healthy rats. The aim of this study was to investigate if hypertension has an effect on vasoconstrictive receptor responses to endothelin 1, sarafotoxin 6c and angiotensin II after stroke by inducing transient middle cerebral artery occlusion in spontaneously hypertensive rats and Wistar-Kyoto rats using the wire-myograph. We demonstrated an increased contractile response to endothelin 1 and extracellular potassium as well as an increased carbachol-induced dilator response in the middle cerebral arteries from hypertensive rats after stroke. This study demonstrates the importance of including risk factors in experimental stroke research.

Correlations of ANP genetic polymorphisms and serum levels with ischemic stroke risk: a meta-analysis

AIMS

This meta-analysis was performed to evaluate the correlations between atrial natriuretic peptide (ANP) genetic polymorphism and its serum ANP levels with the risk of ischemic stroke.

METHODS

The PubMed, CISCOM, CINAHL, Web of Science, Google Scholar, EBSCO, Cochrane Library, and CBM databases were searched for relevant articles published before October 1st, 2013 without language restrictions. Meta-analysis was conducted using the STATA 12.0 software. Crude odds ratios (ORs) or standardized mean difference (SMD) with their 95% confidence interval (95% CI) were calculated. Twelve case-control studies that met all inclusion criteria were included in this meta-analysis. A total of 1285 patients with ischemic stroke and 1088 healthy control subjects were involved in this meta-analysis. Three common single-nucleotide polymorphisms (1837 G/A, 2238 T/C, and 664 G/A) in the ANP gene were assessed.

RESULTS

Our meta-analysis results revealed that ANP 2238 T/C polymorphism might increase the risk of ischemic stroke (C allele vs. T allele: OR=2.26, 95% CI: 1.59-3.23, p<0.001; TC+CC vs. TT: OR=2.26, 95% CI: 1.34-3.81, p=0.002; respectively). However, we found no correlations of ANP 1837 G/A and 664 G/A polymorphisms with ischemic stroke risk (all p>0.05). Furthermore, ischemic stroke patients had higher levels of serum ANP than those of healthy control subjects (SMD=3.12, 95% CI: 1.16-5.07, p=0.002). Our study revealed no publication bias in this meta-analysis (all p>0.05).

CONCLUSION

Our findings indicate that ANP genetic polymorphism and serum ANP levels may contribute to the development of ischemic stroke. Thus, the ANP genetic polymorphism and serum ANP levels could be potential biomarkers for early detection of ischemic stroke.

Pathophysiology of white matter perfusion in Alzheimer's disease and vascular dementia

The pathophysiology of white matter hypoperfusion is poorly understood. Barker et al. quantify ante-mortem hypoperfusion by measuring myelin proteins differentially susceptible to ischaemia, and assess the extent to which vasoregulatory factors protect from or contribute to ischaemic white matter injury in Alzheimer’s disease and vascular dementia.

Little is known about the contributors and physiological responses to white matter hypoperfusion in the human brain. We previously showed the ratio of myelin-associated glycoprotein to proteolipid protein 1 in post-mortem human brain tissue correlates with the degree of ante-mortem ischaemia. In age-matched post-mortem cohorts of Alzheimer’s disease (n = 49), vascular dementia (n = 17) and control brains (n = 33) from the South West Dementia Brain Bank (Bristol), we have now examined the relationship between the ratio of myelin-associated glycoprotein to proteolipid protein 1 and several other proteins involved in regulating white matter vascularity and blood flow. Across the three cohorts, white matter perfusion, indicated by the ratio of myelin-associated glycoprotein to proteolipid protein 1, correlated positively with the concentration of the vasoconstrictor, endothelin 1 (P = 0.0005), and negatively with the concentration of the pro-angiogenic protein, vascular endothelial growth factor (P = 0.0015). The activity of angiotensin-converting enzyme, which catalyses production of the vasoconstrictor angiotensin II was not altered. In samples of frontal white matter from an independent (Oxford, UK) cohort of post-mortem brains (n = 74), we confirmed the significant correlations between the ratio of myelin-associated glycoprotein to proteolipid protein 1 and both endothelin 1 and vascular endothelial growth factor. We also assessed microvessel density in the Bristol (UK) samples, by measurement of factor VIII-related antigen, which we showed to correlate with immunohistochemical measurements of vessel density, and found factor VIII-related antigen levels to correlate with the level of vascular endothelial growth factor (P = 0.0487), suggesting that upregulation of vascular endothelial growth factor tends to increase vessel density in the white matter. We propose that downregulation of endothelin 1 and upregulation of vascular endothelial growth factor in the context of reduced ratio of myelin-associated glycoprotein to proteolipid protein 1 are likely to be protective physiological responses to reduced white matter perfusion. Further analysis of the Bristol cohort showed that endothelin 1 was reduced in the white matter in Alzheimer’s disease (P < 0.05) compared with control subjects, but not in vascular dementia, in which endothelin 1 tended to be elevated, perhaps reflecting abnormal regulation of white matter perfusion in vascular dementia. Our findings demonstrate the potential of post-mortem measurement of myelin proteins and mediators of vascular function, to assess physiological and pathological processes involved in the regulation of cerebral perfusion in Alzheimer’s disease and vascular dementia.

Increased plasma endothelin-1 levels in patients with intracerebral hemorrhage

Endothelins (ETs) are discovered peptides that are widely distributed in neurons and nonneuronal cells of the human nervous system. Previous studies showed that ischemic stroke may be associated with increased plasma ET-1 levels. There are no studies to show plasma ET-1 levels in intracerebral hemorrhage. Plasma ET-1 levels in 30 patients with cerebral hemorrhage within 72 hours after the onset of focal neurological deficit were measured by a microplate enzyme immunoassay. Thirty sex- and age-matched healthy subjects were accepted as a control group. The clinical neurological status in the patients was evaluated according to the modified Matthew Scale. The mean plasma ET-1 level in hemorrhagic stroke patients was significantly higher than in control subjects (2.39±2.08 v 0.65±0.32 fmol/mL, (P < .05). There was a significant difference in ET levels between patients who died in the hospital and patients who survived (P < .05). The mean ET-1 concentration in patients with severe neurologic deficit was significantly higher than in patients with mild neurologic deficit (P < .05). There was a correlation between hematoma volumes and plasma ET-1 levels in the patients (r = 0.66, Pt < .001). The mean plasma ET-1 concentration was found to be significantly higher in patients with intraventricular hemorrhage than in patients without intraventricular hemorrhage (P < 0.05). There were no significant differences in ET-1 levels between supratentorial and infratentorial subgroups or among supratentorial subgroups (P > .05). It was concluded that plasma ET-1 levels were increased in the acute period of hemorrhagic stroke. Plasma ET-1 levels may be associated with hematoma volume, which is related to a poor prognosis of the cerebral hematoma. We suggest that increased plasma ET-1 levels may be a consequence of local cerebral hemorrhage or the acute stress condition of the disease.

Association of a single nucleotide polymorphism of the NPR3 gene promoter with early onset ischemic stroke in an Italian cohort

BACKGROUND

NPR3, located on human chromosome 5 (5p14-p13), encodes the natriuretic peptide receptor type C (NPR-C) that is mainly known as the natriuretic peptide clearance receptor. Involvement of NPR3 in susceptibility to cardiovascular diseases, i.e. hypertension, has been previously shown. With regard to stroke predisposition, evidence for a potential role of genetic variation within or nearby NPR3 has been suggested by a previous genome wide association study.

METHODS

We investigated the contribution to early-onset ischemic stroke susceptibility of the NPR3 -55 C>A transition by genotyping this variant in an Italian cohort of 368 cases and 335 controls.

RESULTS

In a multivariable logistic regression analysis adjusting for age, gender, hypertension, hypercholesterolemia, smoking habit and diabetes, a significant association of the -55 AA genotype with stroke was observed (OR=3.2, 95% CI 1.2-8.3, p=0.016). Remarkably, the polymorphism remained associated with stroke after adjusting for hypertensive status.

CONCLUSION

Our observation obtained in an Italian cohort of early onset ischemic strokes suggests that a NPR3 promoter gene variant could have a role on cerebrovascular disease susceptibility.

Influence of rs5065 atrial natriuretic peptide gene variant on coronary artery disease

OBJECTIVES

The aim of this study was to investigate the impact of rs5065 atrial natriuretic peptide (ANP) gene variant on coronary artery disease (CAD) and its outcomes and to gain potential mechanistic insights on the association with CAD.

BACKGROUND

Either modified ANP plasma levels or peptide structural alterations have been involved in development of cardiovascular events.

METHODS

Three hundred ninety-three control subjects and 1,004 patients undergoing coronary angiography for suspected CAD (432 stable angina [SA], 572 acute coronary syndrome [ACS]) were genotyped for rs5065 ANP gene variant. Data in SA and ACS groups were replicated in an independent population of 482 stable angina patients (rSA) and of 675 ACS patients, respectively. Clinical follow-up was available for both SA and rSA patients. Plasma N-terminal-proANP, myeloperoxidase, lipoprotein-associated phospholipase A2, and oxidized low-density lipoprotein were assessed in a subgroup of rSA patients.

RESULTS

rs5065 minor allele (MA) was an independent predictor of ACS (odds ratio: 1.90; 95% confidence interval: 1.40 to 2.58, p < 0.001). At follow-up, rs5065 MA was independently associated with a significantly higher rate of major adverse cardiovascular events in the SA group, p < 0.001. Data were replicated in the rSA group at follow-up (p = 0.008). Cox proportional hazard analysis tested by 4 models confirmed higher major adverse cardiovascular events risk in rs5065 MA carriers in both SA and rSA cohorts. Significantly higher myeloperoxidase levels were detected in rs5065 MA carriers (n = 597 [345 to 832 μg/l] vs. n = 488 [353 to 612 μg/l], p = 0.038). No association of rs5065 was observed with N-terminal-proANP levels.

CONCLUSIONS

The MA of rs5065 ANP gene variant associates with increased susceptibility to ACS and has unfavorable prognostic value in CAD.

A prospective study of brain natriuretic peptide levels in three subgroups: Stroke with hypertension, stroke without hypertension, and hypertension alone

Aim:

To study brain natriuretic peptide (BNP) levels in three subgroups: patients having stroke with hypertension (HT), those having stroke without HT, and those with HT alone. We also tried to identify whether BNP levels predict the length of stay in hospital and mortality.

Materials and Methods:

The groups were formed by patients who had been admitted to the emergency department in the first 4–12 h after the onset of symptoms. There were 30 stroke patients with a history of HT (group I), 30 stroke patients without a history of HT (group II), and 20 HT patients without stroke (group III). Patients with congestive heart failure, chronic cor pulmonale, severe valvular heart disease, chronic renal failure, liver insufficiency, diabetes mellitus, atrial fibrillation, and those with a history of stroke were excluded from the study since these diseases can affect the plasma BNP levels.

Results:

The demographic characteristics, except the age distribution, were similar among the groups. The mean BNP levels in the three groups were 168.8 ± 223.9 pg/ml, 85.0 ± 75.1 pg/ml, and 84.8 ± 178.3 pg/ml, respectively. The differences between the groups were statistically significant.

Conclusion:

The mean BNP levels were affected by HT and/or stroke. The simultaneous presence of HT and stroke results in a more significant increase BNP than the presence of either stroke or HT alone. When diseases that can affect the plasma BNP levels are excluded, the BNP levels in stroke patients without a history of HT are similar to the levels seen in patients with only HT.

Pentagastrin-induced hemoconcentration in healthy volunteers and patients with panic disorder: effect of pretreatment with ethinyl estradiol

Panic disorder has been associated with both an increased risk of coronary events as well as an increased risk of stroke. Hemoconcentration, with both a decrease in plasma volume and an increase in plasma viscosity, is a possible contributor to the risk of acute ischemic events. Our objectives were to demonstrate the process of hemoconcentration in response to induced panic symptoms and to assess the effect of pretreatment with ethinyl estradiol on panic-induced hemoconcentration. Fifteen male patients with panic disorder and 10 male healthy volunteers were included in a double-blind cross-over placebo-controlled design consisting of two injections of pentagastrin following randomized pretreatment with placebo and ethinyl estradiol. Plasma levels of hematocrit and hemoglobin were assessed at baseline and post-injections, and used to calculate an indirect estimation of the change in plasma volume. Pentagastrin-induced panic symptoms were associated with a mean decrease in plasma volume of 4.8% in the placebo pretreatment condition. Pretreatment with ethinyl estradiol attenuated this effect. The acute hemoconcentration observed in relation to pentagastrin-induced panic symptoms may be relevant to the increased risk of stroke and acute coronary events found in patients with panic disorder.

Factors Affecting the B-Type Natriuretic Peptide Levels in Stroke Patients

Introduction: This study aims to evaluate the relationship between increased B-type natriuretic peptide (BNP) levels in stroke patients and clinical parameters such as age, sex, medical history, blood pressure, Glasgow Coma Score (GCS) and National Institutes of Health Stroke Scale (NIHSS). Materials and Methods: This is a prospective study of 123 stroke patients at the Emergency Department. The patients were divided into 3 groups according to the NIHSS scores. The analysis of the mean difference between continuous variables and plasma BNP levels was assessed using the Mann-Whitney and Kruskal-Wallis. Spearman correlation analysis was performed for BNP and other clinical parameters. Results: The BNP levels of patients who had a medical history of hyperlipidaemia, chronic obstructive pulmonary disease, diabetes mellitus and coronary artery disease were significantly higher than in patients without these diseases. Patients who had atrial fibrillation (AF) in their electrocardiography had significantly higher BNP levels than patients with sinus rhythm. A positive correlation was found between plasma BNP levels with age, blood urea nitrogen (BUN) and NIHSS and a negative correlation was found between plasma BNP levels and GCS. There was a significant difference between the BNP levels of NIHSS groups. Conclusion: We consider that plasma BNP levels could help us in interpreting the general clinical severity, functional capacity and clinical progress of stroke patients at the time of admission in the Emergency Department. In evaluating the high BNP levels in stroke patients, we must keep in mind that age, AF, BUN and medical history can affect the BNP levels. Key words: Emergency Department, Progress, Relationship

Usefulness of natriuretic peptide testing for long-term risk assessment following acute ischemic stroke

Acute-phase levels of B-type natriuretic peptide (BNP) and the N-terminal fragment of the BNP prohormone (NT-pro-BNP) have been associated with mortality when measured in patients with an acute ischemic stroke; however, data regarding the longer-term value of NT-pro-BNP for long-term prognostication after ischemic stroke are limited. Two hundred sixteen patients (mean age 67 +/- 13 years) with acute ischemic stroke were seen 6 months after index admission at which time a structured evaluation including measurement of plasma NT-pro-BNP was performed. Patients were followed for 45 months, with all-cause mortality as the clinical end point. Median NT-pro-BNP concentration for the entire group was 147 pg/ml (10th to 90th percentiles 37 to 869). At follow-up 45 patients (21%) had died. NT-pro-BNP concentrations were significantly higher in decedents (308 pg/ml, 10th to 90th percentiles 74 to 2,279) than in the 171 survivors (132 pg/ml, 10th to 90th percentiles 35 to 570, p <0.001). Patients with NT-pro-BNP < or =147 pg/ml had a significantly improved survival rate on univariate analysis (p <0.001). In multivariate analysis after adjustment for age, stroke severity, heart and renal failures, levels of NT-pro-BNP were an independent predictor of mortality >6 months after stroke (adjusted hazard ratio 1.5, 95% confidence interval 1.1 to 1.9, p = 0.005). In conclusion, NT-pro-BNP concentrations measured during the stable phase after acute ischemic stroke are strongly predictive of long-term mortality.

The complexity of neurobiological processes in acute ischemic stroke

There is an urgent need for improved diagnostics and therapeutics for acute ischemic stroke. This is the focus of numerous research projects involving in vitro studies, animal models and clinical trials, all of which are based on current knowledge of disease mechanisms underlying acute focal cerebral ischemia. Insight in the chain of events occurring during acute ischemic injury is essential for understanding current and future diagnostic and therapeutic approaches. In this review, we summarize the actual knowledge on the pathophysiology of acute ischemic stroke. We focus on the ischemic cascade, which is a complex series of neurochemical processes that are unleashed by transient or permanent focal cerebral ischemia and involves cellular bioenergetic failure, excitotoxicity, oxidative stress, blood-brain barrier dysfunction, microvascular injury, hemostatic activation, post-ischemic inflammation and finally cell death of neurons, glial and endothelial cells.

Blood markers for the prognosis of ischemic stroke: a systematic review

BACKGROUND AND PURPOSE

The performance of validated prognostic clinical models in acute ischemic stroke might be improved by addition of data on blood biomarkers.

METHODS

We searched Medline and EMBASE from 1966 to January 2007 for studies of blood markers in patients with ischemic stroke and an assessment of outcome (death, disability, or handicap). We adopted several strategies to reduce bias.

RESULTS

Studies were generally small (median number of subjects, 85; interquartile range, 49 to 184). Few had evidence of a sample size calculation (7 of 82 [9%]) or reported blinding to whether patients had stroke (21 of 82 [26%]). Of the 66 studies reporting a measure of association, 10 did not adjust for age or stroke severity, 14 adjusted for age, 7 adjusted for severity, and 35 adjusted for both; 30% (20 of 66) used a data-dependent threshold to predict good or bad outcome. There was evidence of within-study reporting bias and publication bias. Cardiac markers showed the most consistent association with poor outcome.

CONCLUSIONS

Blood biomarkers might provide useful information to improve the prediction of outcome after acute ischemic stroke. However, this review showed that many studies were subject to bias. Although some markers had some predictive ability, none of the studies was able to demonstrate that the biomarker added predictive power to a validated clinical model. The clinical usefulness of blood biomarkers for predicting prognosis in the setting of ischemic stroke has yet to be established.

Plasmatic B-type natriuretic peptide and C-reactive protein in hyperacute stroke as markers of CT-evidence of brain edema

OBJECTIVE

Plasmatic B-type-natriuretic peptide (NT-PBNP) and C-reactive protein (CRP) have been reportedly elevated in stroke patients; however their clinical significance remains uncertain. The purpose of this work is to investigate whether elevation of these proteins at baseline predicts CT-evidence of brain edema.

METHODS

We recruited 41 consecutive patients with stroke and determined NT-PBNP and CRP at baseline (within 5 hours after onset), after 48-72 hours, and at discharge. Stroke severity was measured by means of the NIHS scale at baseline and at discharge. We also carried out brain CT at admittance and after 48 hours.

RESULTS

There were 29 ischemic strokes and 12 hemorrhagic strokes. Evidence of brain edema on delayed scan was seen in 14 patients. Baseline levels of NT-PBNP did not predict CT-evidence of edema but CRP levels did so significantly (0.7 mg/dl in patients without edema versus 4.7 mg in patients with edema; p=0.001). Both NT-PBNP and PC levels correlated poorly to NIHSS score and increased markedly from baseline to the second determination in patients with edema. For these patients the NT-PBNP increase was 133.6 pmol/l in comparison to 1.58 pmol/l in patients without edema (p=0.002). Neither CRP nor NT-PBNP baseline levels were predictive of dependency or death.

CONCLUSIONS

We conclude that CRP at baseline but not NT-PBNP predicts CT evidence of brain edema in stroke patients. We hypothesize that NT-PBNP levels elevated in response to edema after 48 hours of admission.

Vasoactive peptides in cardiovascular (patho)physiology

Numerous vasoactive agents play an important physiological role in regulating vascular tone, reactivity and structure. In pathological conditions, alterations in the regulation of vasoactive peptides result in endothelial dysfunction, vascular remodeling and vascular inflammation, which are important processes underlying vascular damage in cardiovascular disease. Among the many vasoactive agents implicated in vascular (patho)biology, angiotensin II (Ang II), endothelin (ET), serotonin and natriuretic peptides appear to be particularly important because of their many pleiotropic actions and because they have been identified as potential therapeutic targets in cardiovascular disease. Ang II, ET-1, serotonin and natriuretic peptides mediate effects via specific receptors, which belong to the group of G-protein-coupled receptors. ET, serotonin and Ang II are primarily vasoconstrictors with growth-promoting actions, whereas natriuretic peptides, specifically atrial, brain and C-type natriuretic peptides, are vasodilators with natriuretic effects. Inhibition of vasoconstrictor actions with drugs that block peptide receptors, compounds that inhibit enzymes that generate vasoactive peptides or agents that increase levels of natriuretic peptides are potentially valuable therapeutic tools in the management of cardiovascular diseases. This review focuses on ET, natriuretic peptides and serotonin. The properties and distribution of these vasoactive agents and their receptors, mechanisms of action and implications in cardiovascular (patho)physiology will be discussed.

Serial Measurements of N-Terminal pro-Brain Natriuretic Peptide after Acute Ischemic Stroke

BACKGROUND

The exact time-course of N-terminal pro-brain natriuretic peptide (NT-proBNP) and the prognostic importance in the immediate phase of ischemic stroke have not been established.

METHODS

NT-proBNP was measured daily from admission to day 5 and again at 6-month follow-up in 250 consecutive patients with acute ischemic stroke.

RESULTS

NT-proBNP peaked the day after onset of symptoms (p = 0.007) followed by a decrease until day 5 (p = 0.001, ANOVA). At 6-month follow-up the difference in the level of NT-proBNP was unchanged compared to day 5 (p = 0.42). NT-proBNP levels > or =615 pg/ml at day 2 after onset of symptoms was associated with 6-month mortality.

CONCLUSION

NT-proBNP peaks the day after onset of symptoms in patients with acute ischemic stroke. A single measurement of NT-proBNP appears to be an indicator of 6-month mortality.

Natriuretic peptide Val7Met substitution and risk of coronary artery disease in Greek patients with familial hypercholesterolemia

Atrial natriuretic peptide (ANP or NPPA) is the precursor protein of the form of amyloidosis called isolated atrial amyloid (IAA), which is related to the increased incidence of cardiac pathological conditions with age. Familial hypercholesterolemia (FH) patients are characterized by high concentrations of low-density lipoprotein cholesterol (LDL-C), which frequently gives rise to premature coronary artery disease (CAD). However, not all FH patients have the same clinical phenotype. The aim of the present study was to assess the relationship between ANP polymorphisms and apolipoprotein (Apo) A1 levels and CAD risk in FH patients. Transition T2238C, which leads to ANP with two additional arginines, and G664A (Val7Met) were investigated with lipid values and clinical phenotype in 83 FH patients. ApoA1 and HDL cholesterol levels were lower in GA patients compared to GG homozygotes for the G664A polymorphism. No association was found between the G664A polymorphism and CAD in our population. Moreover, ApoA1 and high-density lipoprotein cholesterol (HDL-C) levels did not differ among the different genotypes of the T2238C polymorphism, even after adjusting for age and sex. The 664A allele of the ANP polymorphism is associated with lower levels of ApoA1 and HDL-C in FH patients, but not with CAD risk. Concerning the T2238C polymorphism, no effect was found on lipid parameters or CAD incidence.

N-terminal pro-brain natriuretic peptide levels are elevated in patients with acute ischemic stroke

Brain natriuretic peptide (BNP) is a counterregulatory hormone released by the ventricles of the heart. Its main actions are natriuresis and vasodilation. The authors studied N-terminal pro-brain natriuretic peptide (NT-proBNP) levels soon after an acute ischemic stroke. They compared plasma NT-proBNP concentrations in 30 patients with an acute ischemic stroke with those of 30 controls. The 2 groups were adjusted for age and gender, and there were no significant differences in vascular risk factors and left ventricular systolic and diastolic function. Venous samples were collected within the first 11.8 +/-1.2 hours after the onset of symptoms and again on day 6. Brain computed tomography/magnetic resonance imaging (CT/MRI) was performed on the same days (day 0 and day 6) in order to assess the site (carotid or vertebrobasilar), cause (atherothrombotic, cardioembolic, or lacunar), and size (large, medium, or small) of the brain infarct. NT-proBNP levels were elevated in patients with acute stroke (129.9 +/-9.9 fmol/mL) compared with the controls (90.8 +/-6.3 fmol/mL, p <0.05). These levels remained elevated at day 6 (113.5 +/-13.0 fmol/mL). NT-proBNP at admission was significantly higher in cardioembolic compared with atherothrombotic infarctions. There was no correlation between circulating NT-proBNP and stroke topography, infarct size, or severity as assessed by the National Institutes of Health Stroke Scale (NIHSS) at any of the 2 time points (admission and day 6). NT-proBNP levels were raised in patients with acute ischemic stroke; this effect persisted until day 6. The authors suggest that neurohumoral activation occurs in patients with acute ischemic stroke, either reflecting a counterbalancing vasodilating response to the cerebral ischemia or direct myocardial dysfunction.

Physiology and pathophysiology of Na+/H+ exchange and Na+ -K+ -2Cl- cotransport in the heart, brain, and blood

Maintenance of a stable cell volume and intracellular pH is critical for normal cell function. Arguably, two of the most important ion transporters involved in these processes are the Na+/H+ exchanger isoform 1 (NHE1) and Na+ -K+ -2Cl- cotransporter isoform 1 (NKCC1). Both NHE1 and NKCC1 are stimulated by cell shrinkage and by numerous other stimuli, including a wide range of hormones and growth factors, and for NHE1, intracellular acidification. Both transporters can be important regulators of cell volume, yet their activity also, directly or indirectly, affects the intracellular concentrations of Na+, Ca2+, Cl-, K+, and H+. Conversely, when either transporter responds to a stimulus other than cell shrinkage and when the driving force is directed to promote Na+ entry, one consequence may be cell swelling. Thus stimulation of NHE1 and/or NKCC1 by a deviation from homeostasis of a given parameter may regulate that parameter at the expense of compromising others, a coupling that may contribute to irreversible cell damage in a number of pathophysiological conditions. This review addresses the roles of NHE1 and NKCC1 in the cellular responses to physiological and pathophysiological stress. The aim is to provide a comprehensive overview of the mechanisms and consequences of stress-induced stimulation of these transporters with focus on the heart, brain, and blood. The physiological stressors reviewed are metabolic/exercise stress, osmotic stress, and mechanical stress, conditions in which NHE1 and NKCC1 play important physiological roles. With respect to pathophysiology, the focus is on ischemia and severe hypoxia where the roles of NHE1 and NKCC1 have been widely studied yet remain controversial and incompletely elucidated.

Obstructive sleep apnea: Plasma endothelin-1 precursor but not endothelin-1 levels are elevated and decline with nasal continuous positive airway pressure

Assessment of plasma endothelin-1 (ET-1) reveals conflicting results in cerebral and noncerebral conditions. Obstructive sleep apnea (OSA) syndrome has been used as a definite challenge for the investigation of endothelin measurements. Despite marked sleep-related breathing disturbances in untreated patients peripherally measurable ET-1 concentrations remained within the normal range and did not change after an appropriate therapy with continuous positive airway pressure (CPAP). In contrast, its precursor, big ET-1, was considerably elevated in untreated patients and dropped to normal values after long-term CPAP depending on compliance. Relatively stable big ET-1 elevations in untreated patients, during sleep and wakefulness, suggest that a general endothelial alteration beyond that explained by a direct impact of nocturnal breathing disturbances on the vascular system occurs. CPAP-therapy effectively lowered plasma big ET-1 in compliant patients and thus possibly their related risk for vascular diseases. Big ET-1 has been demonstrated to be a more appropriate marker of endothelial alteration than ET-1 because of its longer half-life. Simultaneous measurements are to be recommended.

Effect of endothelin antagonist (TAK-044) on cerebral ischemic volume, oxidative stress markers and neurobehavioral parameters in the middle cerebral artery occlusion model of stroke in rats

Stroke causes brain injury in millions of people world wide each year. Despite the enormity of problem, currently there is no established therapy, which can restore the blood flow at infracted area and also improve the neurological deficit. The present study was carried out to investigate the effect of an endothelin antagonist (TAK-044) in middle cerebral artery (MCA) occlusion model of acute ischemic stroke in rats. Male Wistar rats were pretreated with TAK-044 (5 mg/kg, i.p.) for 7 days and thereafter subjected to focal ischemia by occlusion of MCA using intraluminal thread for two hours. 30 min after reperfusion the animals were subjected to diffusion-weighted imaging (DWI) for assessment of protective effect. Twenty-four hours later the motor performance was tested and subsequently the animals were sacrificed for estimation of markers of oxidative stress; malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD). Control group received vehicle (saline) and similar experimental protocol was followed. In the TAK-044 pretreated group, percent hemispheric lesion area (% HLA) in DWI was significantly attenuated 17.5 +/- 0.5% as compared to control group 61.2 +/- 5.9%. Significant motor impairment, with significant elevated levels of MDA, decrease in GSH and SOD were observed in the vehicle treated MCA occluded rats. Pretreatment with TAK-044 prevented the motor impairment and significantly reversed the changes in markers of oxidative stress (MDA, GSH and SOD). In addition to well-known vasodilatory effect, TAK-044 has recently been documented to have antioxidant and anti-inflammatory properties. These effects can contribute to the protection afforded by TAK-044 in the present study.

A selective endothelin ETA receptor antagonist, SB 234551, improves cerebral perfusion following permanent focal cerebral ischemia in rats

In recent experimental studies, a selective antagonist of endothelin ET(A) receptors, SB 234551, improved neurological and histological outcome in both head trauma and transient focal cerebral ischemia. The present study was conducted to ascertain the degree to which hemodynamic alterations are responsible for this therapeutic effect in a model of permanent middle cerebral artery occlusion (MCAo) in rats. Anesthetized Sprague-Dawley rats were subjected to permanent MCAo by insertion of an intraluminal nylon suture coated with poly-L-lysine. The agent (SB 234551, 30 microg/kg/min = 1.8 mg/kg/h) or vehicle (PBS; 0.6 ml/h) was administered by i.v. infusion beginning 15 min after onset of MCAo and lasting for 23.75 h. Autoradiographic measurement of local cerebral blood flow (lCBF) was performed at 24 h. Physiological data were similar among groups. SB 234551 augmented perfusion by 1.7- to 1.8-fold in both the ischemic hemisphere and in the contralateral (non-ischemic) hemisphere when compared to vehicle-treated ischemic animals. In the ischemic hemisphere, the brain regions significantly benefited were those lying outside the zone of most dense ischemia (i.e., paramedian cortex and thalamus), while in the non-ischemic hemisphere all regions measured showed significant lCBF augmentation. This study demonstrates that SB 234551 therapy results in significant improvement of local cerebral perfusion in the ischemic as well as in the non-ischemic hemispheres after permanent MCAo.

Natriuretic Peptides and Mortality After Stroke

Background and Purpose— Measurement of natriuretic peptides provides prognostic information in various patient populations. The prognostic value of natriuretic peptides among patients with acute stroke is not known, although elevated peptide levels have been observed.

Methods— A series of 51 patients (mean age, 68±11years) with first-ever ischemic stroke underwent a comprehensive clinical examination and measurements of plasma atrial natriuretic peptides (N-ANP) and brain natriuretic peptides (N-BNP) in the acute phase of stroke. The patients were followed-up for 44±21 months. Risk factors for all-cause mortality were assessed. Control populations, matched for gender and age, consisted of 51 patients with acute myocardial infarction (AMI) and 25 healthy subjects.

Results— Plasma concentrations of N-ANP (mean±SD, 988±993 pmol/L) and N-BNP (751±1608 pmol/L) in the stroke patients were at the same level as those in the AMI patients (NS for both), but significantly higher than those of the healthy subjects (358±103 pmol/L, P <0.001 and 54±26 pmol/L, P <0.01, respectively). Elevated levels of N-ANP and N-BNP predicted mortality after stroke (risk ratio [RR] 4.3, P <0.01 and RR 3.9, P <0.01, respectively) and after AMI ( P <0.05), and remained independent predictors of death after stroke even after adjustment for age, diabetes, coronary artery disease, and medication (RR 3.9, P <0.05 and RR 3.7, P <0.05, respectively).

Conclusion— Plasma levels of natriuretic peptides are elevated in the acute phase of stroke and predict poststroke mortality.

Significance of recently identified peptides in hypertension: endothelin, natriuretic peptides, adrenomedullin, leptin

Arterial hypertension is one of the major risk factors in cardiovascular and renal disease. Advances in the study of pathophysiologic mechanisms and the relationship between several regulatory systems provide the basis for development of more selective therapeutic strategies. The increasing understanding of the role played by ETs, natriuretic peptides, AM, and leptin opens new frontiers in the care of hypertension and its complications, coronary artery disease and heart failure and other forms of cardiovascular disease.

Plasma nitric oxide (nitrate/nitrite) levels in acute stroke and their relationship with severity and outcome

Endothelium-derived nitric oxide is beneficial in experimental stroke. We assessed plasma NO levels in patients with acute stroke and their association with both severity and outcome. Plasma nitric oxide (NO), assessed as nitrate/nitrite (NOx), cyclic guanosine monophosphate (cGMP, second messenger to NO), L-arginine (substrate for NO) and L-citrulline (co-product with NO) levels were measured in 228 patients with acute ischemic stroke, 49 patients with acute hemorrhagic stroke, and 38 age and gender-matched normal volunteers. Stroke severity was assessed using the Glasgow Coma Scale, and the outcome was judged by discharge destination (home, institution, or dead). In our study, stroke patients had low levels of NOx (micromol/l): ischemic 49.9 (26.1); hemorrhage 41.7 (19.5); and control 64.0 (36.3) (P < .001); L-arginine (micromol/l): ischemic 85.1 (32.3); hemorrhage 69.9 (24.4); and control 104.0 (30.0) (P < .001); and L-citrulline (micromol/l): ischemic 30.5 (12.3); hemorrhage 26.7 (12.1); and control 39.4 (13.5) (P < .001). Cyclic GMP levels were elevated in stroke: ischemic 21.2 (16.1); hemorrhage 24.7 (17.5); and control 15.8 (9.2) (P = .024). Patients who died or became institutionalized had lower NOx, L-arginine, and L-citrulline levels, and higher cyclic GMP levels, than patients who were discharged home. NOx levels were not associated with feeding status in patients. Low levels of NOx are present in stroke and are associated with severity and outcome. Because endothelium-derived NO is beneficial in acute stroke, administering NO might be beneficial in acute stroke.

Impact of the endothelin-A receptor antagonist BQ 610 on microcirculation in global cerebral ischemia and reperfusion

The role of endogenous endothelin-1 in mediating microcirculatory disturbances after global cerebral ischemia was investigated in Mongolian gerbils. The pial microcirculation was studied by intravital fluorescent microscopy before, during, and up to 3 h after occlusion of both carotid arteries for 15 min. Pretreatment was achieved with the peptidergic selective endothelin-A (ET-A) receptor antagonist BQ 610. The neurological outcome was assessed daily for up to 4 days. The antagonist attenuated postischemic leukocyte-endothelium interactions in postcapillary venules, in particular the number of rolling leukocytes was found to be reduced (13.0+/-9.4 x 100 microm(-1) min(-1) in the control vs. 2.0+/-2.5 in the experimental group, P<0.05). The local microvascular perfusion, measured by the arterio-venous transit time, was improved during reperfusion by BQ 610 (1.3+/-0.5 s in the control vs. 0.7+/-0.2 s in the experimental group, P<0.05). The neurological deficit was significantly reduced in animals treated with the ET-A antagonist (P<0.05). The inhibition of the postischemic inflammatory reaction and the reversal of the delayed hypoperfusion may account for the improved neurological outcome. These observations suggest that application of endothelin-A antagonists may be a useful approach to interfere with derangements in cerebral ischemia/reperfusion.

Cortical expression of endothelin receptor subtypes A and B following middle cerebral artery occlusion in rats

This work aimed to define the spatial expression of endothelin A (ET(A)) and B (ET(B)) receptors in the cerebral cortex after permanent middle cerebral artery occlusion (MCAO) and to identify the phenotype of cells expressing ET(A) and ET(B) receptors. Cortical expression of ET(A) and ET(B) receptors was determined at the mRNA level by semi-quantitative reverse transcription-polymerase chain reaction and at the protein level by immunofluorescence staining, 12, 24 and 72 h after MCAO. Cells expressing endothelin receptors were phenotyped by double labelling with antibodies, anti-protein gene product (PGP9.5) and anti-ED1, towards neurons and activated microglia/macrophages, respectively. Both ET(A) and ET(B) receptor mRNA expressions increased significantly in the ipsilateral cortex in a time-dependent manner after MCAO. Robust expression of ET(A) receptors was noted in most neurons of the ischemic core and in several neurons in laminae 3 and 4 of the peri-infarct region 24 and 72 h after MCAO. ET(B) receptor immunoreactivity was observed in activated microglia/macrophages, beginning 24 h after MCAO. These results provide the first evidence that the action of endothelin during ischemia may be mediated by neuronal ET(A) receptors and activated microglia/macrophage ET(B) receptors. This differential localization of ET(A) and ET(B) receptors suggests that endothelin is involved in some complex neuron-glial interactions in addition to its vascular modulatory activity during ischemia.

Effects of cerebrovascular challenges on plasma endothelin

Plasma endothelin elevations have been associated with cerebrovascular pathology. Mechanisms of stimulation, however, are unknown. Therefore, in healthy subjects a marked physiological cerebrovascular response was experimentally provoked by hypercapnia, hypocapnia, and alternating capneic conditions. During these challenges plasma immunoreactive-endothelin-1 (ir-ET-1) concentrations were determined using a radioimmunassay. Physiological effects were continuously recorded for pCO(2), cerebral blood flow velocity, pulse frequency, and arterial blood pressure. No alterations in plasma ET-1 levels were found upon any of the cerebrovascular stimuli. We conclude that massive cerebrovascular challenges in healthy individuals do not lead to high circulating ET-1 levels.

Exogenous endothelin-1 improves microvascular oxygen balance during focal cerebral ischemia in the rat

We tested the hypothesis that endothelin-1 (ET-1), a cerebrovasoconstrictive peptide, would alter microvascular oxygen balance during focal cerebral ischemia. In this study, male Wistar rats were placed in control (n=9) and ET-1-treated (n=9) groups. Cortical ischemia was induced by middle cerebral artery (MCA) occlusion in isoflurane (1.4%) anesthetized rats. Forty minutes after MCA occlusion, 10(-7) M ET-1 or saline was applied to the ischemic cortex (IC) for a period of 20 min; the fluid was changed every 5 min. After 1 h of ischemia, regional cerebral blood flow (rCBF) was determined using a 14C-iodoantipyrine autoradiographic technique. Regional arterial and venous oxygen saturation were determined microspectrophotometrically. The cerebral blood flow (45% control, 45% ET-l) and oxygen consumption (24% control, 44% ET-1) of the IC were significantly lower than the contralateral cortex. ET-1 of 10(-7) M did not cause a statistically significant alteration in regional cerebral blood flow or oxygen consumption of the IC, but did increase the average venous O(2) saturation of the IC from 50 +/- 1% to 55 +/- 2% (p<0.04). A significant (p<0.05) increase was observed in O(2) supply/consumption ratio in the ET-1-treated IC (2.79 +/- 0.26 ml O(2)/min/100 g in ET-1-treated IC vs. 2.41 +/- 0.12 ml O(2)/min/100 g in the control IC) compared to the control IC. ET-1 also significantly lowered the frequency of small veins with less than 50% O(2) saturation in the IC (39 out of 70 veins in IC vs. 17 out of 70 veins in ET-1-treated IC). Thus, the exogenous application of 10(-7) M ET-1 improved microvascular oxygen supply/consumption balance during focal cerebral ischemia.

Effect of a regulatory mutation on the rat atrial natriuretic peptide gene transcription

To investigate the functional relevance of a regulatory mutation affecting the enhancer element PEA2 of the rat ANP gene we transfected rat cardiomyocytes and aortic endothelial cells with either the mutant or the wild-type ANP promoter construct (-683 +54) and performed CAT assays both at baseline and in response to Phenylephrine and Angiotensin II. In the myocardial cells we also determined the DNA/nuclear protein interaction through electrophoretic mobility shift assay. These studies showed a significantly lower degree of ANP transcription in the presence of the mutant PEA2 site, thus demonstrating its functional significance and the biological relevance of ANP gene structural alterations.

Evaluation of plasma endothelin-1 levels in patients with cerebral infarction

Endothelin-1 (ET-1) is a vasoconstrictor peptide derived from endothelium. Many authors have shown that ischemic stroke is associated with elevated plasma ET-1 levels. Also, the present findings related to plasma ET-1 levels with clinical status, size of the infarction, location of the infarction, and prognosis of the cerebral infarction were contradictory. In this study, plasma ET-1 levels in 30 patients with cerebral infarction within 72 hours after the onset of focal neurologic deficit and at their seventh day postinfarction were measured by a microplate enzyme immunoassay. Thirty sex- and age-matched healthy subjects were accepted as a control group. The mean plasma ET-1 concentrations in patients on admission, in patients at day 7, and in control subjects were 1.93 +/- 1.79, 1.03 +/- 1.02, and 0.65 +/- 0.32 fmol/mL, respectively. The mean plasma ET-1 level of patients on admission was found to be significantly higher than in patients at day 7 and in control subjects (p < 0.05). No significant difference in ET-1 levels was observed between the patients at day 7 and control subjects. Furthermore, there was no correlation between plasma ET-1 concentration and size of infarction, location of infarction, degree of clinical neurologic deficit, or prognosis of cerebral infarction. It was concluded that plasma ET-1 levels shortly after ischemic stroke were increased, which may be associated with the acute-phase reaction of cerebral infarction and may have deleterious effects on development of neuronal injury.

The atrial natriuretic peptide: a changing view

The atrial natriuretic peptide (ANP), a component of the natriuretic peptide family, was discovered in 1981 when de Bold and his coworkers observed a natriuretic effect induced by infusion of atrial extracts in rats. Subsequently, an impressive amount of research has been carried out in order to identify the structure of the active peptide and its receptors, to characterize the biological functions of ANP and its involvement in the pathophysiology of diseases and, finally, its direct contributory role in the pathogenesis of some cardiovascular disorders. ANP plays a key role in the regulation of salt and water balance, as well as of blood pressure homeostasis. In addition, ANP is involved in the pathophysiology of hypertension and heart failure, and exerts a cellular antiproliferative effect in the cardiovascular system. More recently, a direct contributory role of ANP in the development of hypertension and of cerebrovascular disorders has been suggested by the use of molecular genetic approaches. Therefore, our understanding of the pathophysiologic relevance of ANP has changed over time, finally leading to the identification of ANP as a potential determinant of cardiovascular diseases, rather than as a simple marker of cardiac and vascular dysfunctions. This novel view of ANP may open interesting research pathways.