PRESSOR AND NON-PRESSOR EFFECTS OF SODIUM LOADING ON STROKE IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

Esaxerenone: blood pressure reduction and cardiorenal protection without reflex sympathetic activation in salt-loaded stroke-prone spontaneously hypertensive rats

Mineralocorticoid receptor (MR) is involved in the mechanisms of blood pressure elevation, organ fibrosis, and inflammation. MR antagonists have been used in patients with hypertension, heart failure, or chronic kidney disease. Esaxerenone, a recently approved MR blocker with a nonsteroidal structure, has demonstrated a strong blood pressure-lowering effect. However, blood pressure reduction may lead to sympathetic activation through the baroreflex. The effect of esaxerenone on the sympathetic nervous system remains unclear. We investigated the effect of esaxerenone on organ damage and the sympathetic nervous system in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP), a well-established model of essential hypertension with sympathoexcitation and organ damage. Three-week administration of esaxerenone or hydralazine successfully attenuated the blood pressure elevation. Both esaxerenone and hydralazine comparably suppressed left ventricular hypertrophy and urinary albumin excretion. However, renal fibrosis and glomerular sclerosis were suppressed by esaxerenone but not hydralazine. Furthermore, plasma norepinephrine level, a parameter of systemic sympathetic activity, was significantly increased by hydralazine but not by esaxerenone. Consistent with these findings, the activity of the control centers of sympathetic nervous system, the parvocellular region of the paraventricular nucleus in the hypothalamus and the rostral ventrolateral medulla, was enhanced by hydralazine but remained unaffected by esaxerenone. These results suggest that esaxerenone effectively lowers blood pressure without inducing reflex sympathetic nervous system activation. Moreover, the organ-protective effects of esaxerenone appear to be partially independent of its blood pressure-lowering effect. In conclusion, esaxerenone demonstrates a blood pressure-lowering effect without concurrent sympathetic activation and exerts organ-protective effects in salt-loaded SHRSP. Esaxerenone has antihypertensive and cardiorenal protective effects without reflex sympathetic activation in salt-loaded stroke-prone spontaneously hypertensive rats.

Allisartan isoproxil reduces mortality of stroke-prone rats and protects against cerebrovascular, cardiac, and aortic damage

Stroke is a common cause of death and disability. Allisartan isoproxil (ALL) is a new angiotensin II receptor blocker and a new antihypertensive drug discovered and developed in China. In the present study we investigated the therapeutic effects of ALL in stroke-prone renovascular hypertensive rats (RHR-SP) and the underlying mechanisms. The model rats were generated via two-kidney two-clip (2K2C) surgery, which led to 100% of hypertension, 100% of cerebrovascular damage as well as 100% of mortality 1 year after the surgery. Administration of ALL (30 mg · kg-1 · d-1 in diet, for 55 weeks) significantly decreased stroke-related death and prolonged lifespan in RHR-SP, but the survival ALL-treated RHR-SP remained of hypertension and cardiovascular hypertrophy compared with sham-operated normal controls. In addition to cardiac, and aortic protection, ALL treatment for 10 or 12 weeks significantly reduced cerebrovascular damage incidence and scoring, along with a steady reduction of blood pressure (BP) in RHR-SP. Meanwhile, it significantly decreased serum aldosterone and malondialdehyde levels and cerebral NAD(P)H oxidase expressions in RHR-SP. We conducted 24 h continuous BP recording in conscious freely moving RHR-SP, and found that a single intragastric administration of ALL produced a long hypotensive effect lasting for at least 12 h on systolic BP. Taken together, our results in RHR-SP demonstrate that ALL can be used for stroke prevention via BP reduction and organ protection, with the molecular mechanisms related to inhibition of angiotensin-aldosterone system and oxidative stress. This study also provides a valuable scoring for evaluation of cerebrovascular damage and drug efficacy.

Pharmacological characterization of MT-1207, a novel multitarget antihypertensive agent

Hypertension is a serious public health problem worldwide. MT-1207, chemically named 3-(4-(4-(1H-benzotriazole-1-yl)butyl)piperazine-1-yl) benzisothiazole hydrochloride, is a new chemical entity that has entered into clinical trial as antihypertensive agent in China. In this paper we report the pharmacological profile of MT-1207 regarding its acute, subacute, and long-term effects on hypertensive animal models, and its actions on isolated organs in vitro as well as its molecular targets. Blood pressure (BP) was measured in conscious animals; amlodipine was taken as a positive control drug. We showed that both single dose of MT-1207 (1.25-20 mg/kg, ig) in spontaneously hypertensive rats (SHR) and MT-1207 (0.25-6 mg/kg, ig) in two-kidney one-clip (2K1C) dogs dose-dependently decreased BP. MT-1207 quickly decreased BP within 5 min after administration; the hypotensive effect lasted for 8 and 12 h, respectively, in SHR and 2K1C dogs without reflex increase in heart rate. Multiple doses of MT-1207 (5 mg · kg-1 · d-1 in SHR; 2 mg · kg-1 · d-1 in 2K1C dogs, for 7 days) significantly decreased BP, slightly reduced heart rate, and both of them recovered after withdrawal. Long-term administration of MT-1207 (10 mg · kg-1 · d-1 for 4 months or more time) produced a stable BP reduction, improved baroreflex sensitivity, reduced renal and cardiovascular damage in SHR, and delayed stroke occurrence and death in stroke-prone SHR. In isolated rat aortic rings precontracted by adrenaline, KCl, noradrenaline or 5-hydroxytryptamine (5-HT), MT-1207 (10-9-10-4 M) caused concentration-dependent relaxation. In a panel of enzyme activity or radioligand binding assays of 87 molecular targets, MT-1207 potently inhibited adrenergic α1A, α1B, α1D, and 5-HT2A receptors with Ki < 1 nM. The antagonism of MT-1207 against these receptors was confirmed in isolated rabbit arteries. We conclude that MT-1207 is a novel and promising single-molecule multitarget agent for hypertension treatment to reduce hypertensive organ damage and stroke mortality.

Differential Stiffening between the Abdominal and Thoracic Aorta: Effect of Salt Loading in Stroke-Prone Hypertensive Rats

Central artery stiffening is recognized as a cardiovascular risk. The effects of hypertension and aging have been shown in human and animal models but the effect of salt is still controversial. We studied the effect of a high-salt diet on aortic stiffness in salt-sensitive spontaneously hypersensitive stroke-prone rats (SHRSP). Distensibility, distension, and β-stiffness were measured at thoracic and abdominal aortic sites in the same rats, using echotracking recording of the aortic diameter coupled with blood pressure (BP), in SHRSP-salt (5% salted diet, 5 weeks), SHRSP, and normotensive Wistar-Kyoto (WKY) rats. Hemodynamic parameters were measured at BP matched to that of WKY. Histological staining and immunohistochemistry were used for structural analysis. Hemodynamic isobaric parameters in SHRSP did not differ from WKY and only those from the abdominal aorta of SHRSP-salt presented decreased distensibility and increased stiffness compared with WKY and SHRSP. The abdominal and thoracic aortas presented similar thickening, increased fibrosis, and remodeling with no change in collagen content. SHRSP-salt presented a specific increased elastin disarray at the abdominal aorta level but a decrease in elastin content in the thoracic aorta. This study demonstrates the pro-stiffening effect of salt in addition to hypertension; it shows that only the abdominal aorta presents a specific pressure-independent stiffening, in which elastin disarray is likely a key mechanism.

Extracellular visfatin has nicotinamide phosphoribosyltransferase enzymatic activity and is neuroprotective against ischemic injury

AIM

Visfatin, a novel adipokine, is predominantly produced by visceral adipose tissue and exists in intracellular and extracellular compartments. The intracellular form of visfatin is proved to be nicotinamide phosphoribosyltransferase (NAMPT) and exhibits neuroprotection through maintaining intracellular NAD(+) pool. However, whether extracellular form of visfatin has NAMPT activity and the effect of extracellular visfatin in cerebral ischemia are unknown.

METHODS AND RESULTS

Plasma concentrations of visfatin, NAD(+) , and ATP were increased in mice upon cerebral ischemia. Cultured glia, but not neuron, was able to secrete visfatin. Oxygen-glucose deprivation (OGD) stress increased the secretion of visfatin from glia. Extracellular recombinant mouse wild-type visfatin, but not mouse H247A-mutant enzymatic-dead visfatin, had NAMPT enzymatic function in vitro. Treatment of wild-type visfatin, but not H247A-mutant enzymatic-dead visfatin, significantly attenuated detrimental effect of OGD on the cell viability and apoptosis in both cultured mouse neuron and glia. Treatment of neutralizing antibody, abolished the protective effect of extracellular visfatin on cell viability, but failed to block the antiapoptotic effect of extracellular visfatin. At last, we observed that plasma visfatin concentrations decreased in 6-month-old but not 3-month-old SHR-SP compared with that in age-matched Wistar-Kyoto rats. Inhibition of NAMPT enzymatic function of visfatin (by FK866) accelerated the occurrence of stroke in SHR-SP.

CONCLUSIONS

Extracellular visfatin has NAMPT enzymatic activity and maybe be neuroprotective just as intracellular visfatin in cerebral ischemic injury.

Vascular aspects of cognitive impairment and dementia

Hypertension and stroke are highly prevalent risk factors for cognitive impairment and dementia. Alzheimer's disease (AD) and vascular dementia (VaD) are the most common forms of dementia, and both conditions are preceded by a stage of cognitive impairment. Stroke is a major risk factor for the development of vascular cognitive impairment (VCI) and VaD; however, stroke may also predispose to AD. Hypertension is a major risk factor for stroke, thus linking hypertension to VCI and VaD, but hypertension is also an important risk factor for AD. Reducing these two major, but modifiable, risk factors-hypertension and stroke-could be a successful strategy for reducing the public health burden of cognitive impairment and dementia. Intake of long-chain omega-3 polyunsaturated fatty acids (LC-n3-FA) and the manipulation of factors involved in the renin-angiotensin system (e.g. angiotensin II or angiotensin-converting enzyme) have been shown to reduce the risk of developing hypertension and stroke, thereby reducing dementia risk. This paper will review the research conducted on the relationship between hypertension, stroke, and dementia and also on the impact of LC-n3-FA or antihypertensive treatments on risk factors for VCI, VaD, and AD.

E-selectin deficiency attenuates brain ischemia in mice

AIMS

To determine whether E-selectin deficiency can attenuate brain ischemia in a mouse model of focal cerebral ischemia.

METHODS

E-selectin was determined in spontaneously hypertensive rats (SHRs) and stroke-prone spontaneously hypertensive rats (SHR-SPs). E-selectin knockout (Es(-/-) ) mice and wild-type control (WT) mice underwent permanent distal middle cerebral artery occlusion (MCAO). Behavioral analyses were performed followed by the measurement of infarct areas. Myeloperoxidase (MPO) protein was determined by Western blot. IL-6, IL-1β, and TNF-α were detected by ELISA. In situ detection of apoptotic cells was performed by TUNEL staining.

RESULTS

The brain and serum E-selectin levels were higher in SHR-SPs than in SHRs (P < 0.05) after salt intake. E-selectin deficiency improved neurological function and reduced infarct area in cerebral ischemic mice. MPO and IL-1β were lower in Es(-/-) mice than in WT mice. In addition, the number of apoptotic cells in Es(-/-) mice was significantly less than in WT mice after MCAO.

CONCLUSIONS

E-selectin deficiency presents protective effect on cerebral ischemia. This protective effect is likely achieved by the inhibition of inflammation and apoptosis.

Importance of riboflavin kinase in the pathogenesis of stroke

AIMS

To explore risk factors for stroke independent of hypertension and the relationship between riboflavin kinase (RFK) and stroke.

METHODS

Gene expression profiling in the brains of spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) was comparatively analyzed by gene chips. The differentially expressed gene RFK was further verified by q-PCR and Western blot. The protective role of RFK-regulated flavins (including riboflavin, flavin mononucleotide, and flavin adenine dinucleotide) in stroke was observed in middle cerebral artery occlusion (MCAO) mice. Influence of flavins on apoptosis and death in oxygen and glucose deprivation (OGD)-treated neurons was examined by flow cytometry. Bax and Bcl-2 proteins were detected by Western blot.

RESULTS

Of the 76 differentially expressed genes, 41 genes were upregulated, and 35 genes were downregulated in SHRSP as compared with SHR. RFK was significantly downregulated in SHRSP. Flavins markedly decreased infarct area in MCAO mice, inhibited apoptosis and death in OGD-treated neurons, and decreased Bax protein expression.

CONCLUSIONS

Physiological downregulation of RFK may be a new potential risk factor for stroke, which probably affects the absorbance and utility of riboflavin and further destroys the protective effect of flavins on stroke. RFK might act as a therapeutic target for stroke.

Visfatin and cardio-cerebro-vascular disease

Nicotinamide phosphoribosyltransferase is the rate-limiting enzyme that catalyzes the first step in the biosynthesis of nicotinamide adenine dinucleotide from nicotinamide. This protein was originally cloned as a putative pre-B cell colony-enhancing factor and also found to be a visceral fat-derived adipokine (visfatin). As a multifunctional protein, visfatin plays an important role in immunity, metabolism, aging, inflammation, and responses to stress. Visfatin also participates in several pathophysiological processes contributing to cardio-cerebro-vascular diseases, including hypertension, atherosclerosis, ischemic heart disease, and ischemic stroke. However, whether visfatin is a friend or a foe in these diseases remains uncertain. This brief review focuses on the current understanding of the complex role of visfatin in the cardio-cerebro-vascular system under normal and pathophysiological conditions.

Increased oxidative stress is responsible for severer cerebral infarction in stroke-prone spontaneously hypertensive rats

AIMS

To examine the role of increased oxidative stress in the pathogenesis of cerebral infarction in stroke in stroke-prone spontaneously hypertensive rats (SHR-SP).

METHODS

The differentially expressed brain protein profile was examined in spontaneously hypertensive rats (SHR) (control group) and SHR-SP using two-dimensional fluorescent difference gel electrophoresis (2D-DIGE). In addition, oxidative stress indicators including total antioxidation capacity (TAC), glutathione peroxidase (GPx) activity, and maleic dialdehyde (MDA) were also measured. Lastly, SHR-SP were randomly divided into untreated and treated (vitamins C (200 mg/kg/day) and E (100 mg/kg/day)) groups. After treatment for 4 weeks, half of the animals were sacrificed for detection of TAC, GPx, and MDA. The remaining rats underwent middle cerebral artery occlusion (MCAO) and the infarct areas were measured.

RESULTS

Compared with SHR, the infarct area of SHR-SP was larger (P < 0.01), and the antioxidative proteins including glutathione S-transferase (GST) Pi2 and GST A5 were lower; TAC and GPx activities were decreased and MDA levels. Treatment with vitamins C and E decreased MDA, and increased TAC and GPx activity significantly in SHR-SP, while also decreasing the infarct area (P < 0.01).

CONCLUSIONS

Our findings indicate that oxidative stress plays an important role in the pathogenesis of cerebral ischemia.

Dietary salt exacerbates isoproterenol-induced cardiomyopathy in rats

Spontaneously hypertensive heart failure rats (SHHFs) take longer to develop compensated heart failure (HF) and congestive decompensation than common surgical models of HF. Isoproterenol (ISO) infusion can accelerate cardiomyopathy in young SHHFs, while dietary salt loading in hypertensive rats induces cardiac fibrosis, hypertrophy, and--in a minority-congestive HF. By combining ISO with dietary salt loading in young SHHFs, the authors sought a nonsurgical model that is more time--and resource-efficient than any of these factors alone. The authors hypothesized that salt loading would enhance ISO-accelerated cardiomyopathy, promoting fibrosis, hypertrophy, and biochemical characteristics of HF. SHHFs (lean male, 90d) were infused for 4 wk with ISO (2.5 mg/kg/day) or saline. After 2 wk of infusion, a 6-wk high-salt diet (4%, 6%, or 8% NaCl) was initiated. Eight percent salt increased heart weight, HF markers (plasma B-type natriuretic peptide, IL-6), lung lymphocytes, and indicators of lung injury and edema (albumin and protein) relative to control diet, while increasing urine pro-atrial natriuretic peptide relative to ISO-only. High salt also exacerbated ISO-cardiomyopathy and fibrosis. Thus, combining ISO infusion with dietary salt loading in SHHFs holds promise for a new rat HF model that may help researchers to elucidate HF mechanisms and unearth effective treatments.

Effects of low-dose ketanserin on atherosclerosis in rats and rabbits

The present study was designed to test the hypothesis that a small dose of ketanserin, which enhances baroreflex activity, prevents the early lesions of atherosclerosis. In experiment 1, baroreflex sensitivity (BRS) was measured in 31 spontaneously hypertensive rats (SHRs) in a conscious state using a computerized blood pressure monitoring system. Four weeks later, the rats were administered vitamin D3 and fed a high-cholesterol diet for 8 weeks to induce atherosclerosis. Then their hearts and aortae were removed for pathological examination. A negative correlation was found between BRS and the scores of coronary (r = -0.460, P < 0.01) and aortic atherosclerosis (r = -0.448, P < 0.05) in SHR. In experiment 2, SHRs were divided into 3 groups (n = 10 in each group) and received a dose of ketanserin of 0.3, 1.0, and 3.0 mg/kg (i.g.), respectively. At the smallest dose (0.3 mg/kg), ketanserin did not lower blood pressure but enhanced BRS. In experiment 3, SHRs were administered vitamin D3, fed a high-cholesterol diet, and simultaneously treated with low-dose ketanserin. The atherosclerosis scores of the treatment group were significantly lower than those of the control group (coronary score: 0.90 ± 0.14 vs. 1.76 ± 0.27, P < 0.05; aortic scores: 1.00 ± 0.39 vs. 2.18 ± 0.41, P < 0.05). In experiment 4, male New Zealand White rabbits were fed a high-cholesterol diet and treated with low-dose ketanserin at the same time. The atherosclerosis scores of the treatment group were significantly lower than those of the control group (aortic scores: 0.26 ± 0.20 vs. 0.60 ± 0.31, P < 0.05). In conclusion, the present study demonstrated, for the first time, that low-dose ketanserin prevented the development of atherosclerosis independent of its blood pressure lowering action in SHRs and New Zealand White rabbits at least in part via enhancement of arterial baroreflex function.

The role of the renin—angiotensin system in the pathogenesis of intracranial aneurysms

Introduction: Recent work has begun to elucidate the pathogenesis of intracranial aneurysms (IA) and has shown that many genes are involved in the risk for this condition. There has also been increasing research interest in the renin—angiotensin system (RAS) in the brain and its involvement in a range of cardiovascular and neurological disorders. The possibility that the RAS is implicated in the pathogenesis of IA merits further investigation. The aim of this article is to review the literature on the pathogenesis of IA and the pathophysiological significance of the brain RAS, and to identify directions for research into their association.

Methods and results : A survey of the literature in these fields shows that although factors contributing to systemic hypertension predispose to IA, a large number of genes involved in endothelial cell adhesion, smooth muscle activity, extracellular matrix dynamics and the inflammatory and immune responses are also implicated. The brain RAS has a significant role in regulating blood pressure and in maintaining cerebrovascular autoregulation, but angiotensin II receptors are also involved in the maintenance of endothelial cell and vascular smooth muscle function and in the inflammatory response in the brain.

Conclusions: There is strong, albeit largely circumstantial, evidence in the literature for a relationship between the brain RAS and the formation of IA. Research on the association between polymorphisms in RAS-related genes and the incidence of unruptured and ruptured IA is indicated.

Circulating and local visfatin/Nampt/PBEF levels in spontaneously hypertensive rats, stroke-prone spontaneously hypertensive rats and Wistar-Kyoto rats

Visfatin (also known as nicotinamide phosphoribosyltransferase and pre-B cell colony-enhancing factor) is a multifunctional protein. Visfatin has been reported to be involved in several biological processes in the cardiovascular system, . However, the role of visfatin in hypertension is still unclear. In this study, we examined the circulating and local adipose visfatin levels in spontaneously hypertensive rats (SHR), stroke-prone spontaneously hypertensive rats (SHR-SP), and in their normotensive control Wistar-Kyoto (WKY). SHR and SHR-SP rats exhibited lower body weight, lower fat tissue and hypolipidemia. No differences of serum visfatin levels were observed in SHR/SHR-SP and WKY. Serum visfatin levels did not correlate to serum glucose, lipids, insulin, and fat pad weights, but significantly correlated to weights of skeletal muscle. Visfatin expression in visceral fat tissue was slightly lower in SHR-SP compared with that in WKY. Moreover, there were no significant differences of visfatin expression in skeletal muscles among WKY, SHR and SHR-SP. Finally, visfatin protein was detected in L6 rat skeletal muscle cell culture medium, indicating that visfatin was secreted from skeletal muscle cells. Thus, our results may provide useful information for understanding the characteristic of visfatin in hypertensive models, and support the view that visfatin may be a myokine.

Blood pressure reduction combining baroreflex restoration for stroke prevention in hypertension in rats

Blood pressure reduction is an important and effective strategy in stroke prevention in hypertensives. Recently, we found that baroreflex restoration was also crucial in stroke prevention. The present work was designed to test the hypothesis that a combination of blood pressure reduction and baroreflex restoration may be a new strategy for stroke prevention. In Experiment 1, the effects of ketanserin (0.3, 1, 3, 10 mg/kg), amlodipine (0.3, 1, 2, 3 mg/kg) and their combination (1 + 0.3, 1 + 1, 1 + 2, 1 + 3 mg/kg) on blood pressure and baroreflex sensitivity (BRS) of stroke-prone spontaneously hypertensive rats (SHR-SP) were determined under conscious state. It was found that both amlodipine and ketanserin decreased blood pressure dose-dependently. Ketanserin enfanced BRS from a very small dose but amlodipine enfanced BRS only at largest dose used. At the dose of 1 + 2 mg/kg (ketanserin + amlodipine), the combination possessed the largest synergism on blood pressure reduction. In Experiments 2 and 3, SHR-SP and two-kidney, two-clip (2K2C) renovascular hypertensive rats received life-long treatments with ketanserin (1 mg/kg) and amlodipine (2 mg/kg) or their combination (0.5 + 1, 1 + 2, 2 + 4 mg/kg). The survival time was recorded and the brain lesion was examined. It was found that all kinds of treatments prolonged the survival time of SHR-SP and 2K2C rats. The combination possessed a significantly better effect on stroke prevention than mono-therapies. In conclusion, combination of blood pressure reduction and baroreflex restoration may be a new strategy for the prevention of stroke in hypertension.

New strategies for the prevention of stroke

1. Stroke is a major cause of disability and death worldwide. It is preferable to prevent stroke rather than to treat it and, for the prevention of stroke, all risk factors relating to stroke need to be understood. The present paper reviews potential new strategies for the prevention of stroke based on findings of new risk factors, as well as classical risk factors. 2. Recently, new risk factors related to stroke were reported, including dysfunction of the arterial baroreflex, pro-inflammatory cytokines, vitamins and hormone deficiency. Correspondingly, therapies targeting these risk factors where shown to significantly reduce the incidence and/or severity of stroke. 3. Because the genesis of stroke is multifactorial, the prevention of stroke should not target one risk factor only. Combination therapies with drugs acting on different risk factors may be more effective in the prevention of stroke.

A new method for assessing variability of 24 h blood pressure and its first application in 1526 elderly men

1. Blood pressure variability (BPV) includes physiological and random variations in blood pressure (BP). Commonly used approaches, such as standard deviation (SD) and weighted standard deviation (wSD) methods, do not efficiently assess random variation in BP. In the present study, we propose a novel method to assess individual BP variations, extracting random variation in BP by eliminating physiological variation mathematically. This novel assessment method furthers our understanding of the relationship between BP variation and lacunar infarction (LACI). 2. In the present study, we analysed ambulatory blood pressure monitoring recordings taken from 1526 men aged 60-98 years of age. Individual curves were created using a mathematical method and the related BP variation calculated, namely the SD for individual BP variations. In addition, correlations between LACI and BP variations as determined by the classical SD method, wSD and our novel assessment method (SD') were evaluated. 3. The results demonstrated that 24 h variations in systolic BP (SBP) were closely associated with LACI when the SD and wSD methods were used (P < 0.05), but the most significant correlations were observed when the SD' method was used (P < 0.01). Furthermore, using SD' yielded the lowest value of the parameter P among the three different methods used to analyse BPV. Using the SD' method, a significant correlation was found between variations in SBP and the incidence of LACI (P < 0.05). It was found that the incidence of LACI increased by 2% with each 1 mmHg increase in SBP variation. 4. In conclusion, our novel assessment method enables mathematical removal of interference from physiological BP variation and the results show a better correlation with LACI. Thus, our novel method may be considered a simple index of 24 h BP variation that is superior to conventional SD and wSD methods.

Effects of allisartan, a new AT(1) receptor blocker, on blood pressure and end-organ damage in hypertensive animals

AIM

To investigate the effects of allisartan, a new angiotensin II type 1 (AT(1)) receptor antagonist, on blood pressure (BP) and end-organ damage (EOD) in hypertensive rats and dogs.

METHODS

First, a single dose of allisartan was given intragastrically to evaluate the BP reduction in spontaneously hypertensive rats (SHRs), two kidney-one clip (2K1C) renovascular hypertensive rats and dogs, and Beagle dogs with angiotensin II-induced hypertension. Second, allisartan was mixed in rat chow for long-term treatment. After 4 months of drug administration, rats were instrumented to determine BP and baroreflex sensitivity (BRS). Observation of morphologic changes was used to estimate EOD. Third, the acute toxicity of allisartan was compared with that of losartan in mice.

RESULTS

BP was significantly decreased after intragastric administration of allisartan in SHRs, 2K1C rats, 2K1C dogs and Beagle dogs with angiotensin II-induced hypertension. Compared with the control, SHRs that received long-term treatment with allisartan exhibited an improved BRS and organ protective effects. Mice who were administered allisartan experienced less acute toxicity than those treated with losartan.

CONCLUSION

Allisartan is highly effective for BP reduction and organ protection with low toxicity.