Myocardial ischemia-reperfusion enhances transcriptional expression of endothelin-1 and vasoconstrictor ETB receptors via the protein kinase MEK-ERK1/2 signaling pathway in rat

Snake Venom Components as Therapeutic Drugs in Ischemic Heart Disease

Ischemic heart disease (IHD), especially myocardial infarction (MI), is a leading cause of death worldwide. Although coronary reperfusion is the most straightforward treatment for limiting the MI size, it has nevertheless been shown to exacerbate ischemic myocardial injury. Therefore, identifying and developing therapeutic strategies to treat IHD is a major medical challenge. Snake venoms contain biologically active proteins and peptides that are of major interest for pharmacological applications in the cardiovascular system (CVS). This has led to their use for the development and design of new drugs, such as the first-in-class angiotensin-converting enzyme inhibitor captopril, developed from a peptide present in Bothrops jararaca snake venom. This review discusses the potential usefulness of snake venom toxins for developing effective treatments against IHD and related diseases such as hypertension and atherosclerosis. It describes their biological effects at the molecular scale, their mechanisms of action according to their different pharmacological properties, as well as their subsequent molecular pathways and therapeutic targets. The molecules reported here have either been approved for human medical use and are currently available on the drug market or are still in the clinical or preclinical developmental stages. The information summarized here may be useful in providing insights into the development of future snake venom-derived drugs.

The Impact of Trimetazidine on Cardiac Fibrosis, Inflammation, and Function in Ischemic Cardiomyopathy Patients

BACKGROUND

Previous studies have shown that Trimetazidine (TMZ) improves vascular endothelial function and reduces the inflammatory process progression. However, limited data have been available regarding its effects on myocardial fibrosis following ischemia and causing left ventricular dysfunction.

PURPOSE

To investigate the impact of TMZ adjuvant therapy for ischemic cardiomyopathy (ICM) on cardiac fibrosis, vascular endothelial function, inflammation, and myocardial functions.

METHODS

This randomized, double-blind controlled clinical trial included 48 patients (aged 59.4 ± 9 years) with ICM who were randomly assigned to two groups: TMZ 35 mg twice daily and placebo in addition to conventional ICM medications. All patients received the tablets for 3 months. Both groups were then compared in terms of connective tissue growth factor (CTGF), endothelin-1 (ET-1), tumor necrosis factor-alpha (TNF-α), and some echocardiographic indices, weekly angina attacks and nitrate consumption before and after treatment.

RESULTS

No significant differences between CTGF, ET-1, and TNF-α levels, in addition to some echocardiographic indices, were observed between both groups before treatment. After treatment, the TMZ group had significantly lower ET-1 than the placebo group, with both groups exhibiting a substantial decrease in TNF-α and CTGF. The TMZ group had lower mean ± SD levels for TNF-α and CTGF and showed significant improvement in echocardiographic indices and weekly angina attacks after treatment.

CONCLUSION

Adjunctive TMZ therapy for ICM effectively improved vascular endothelial function and reduced inflammation. Furthermore, our exploratory findings may be used to provide new information on the potential effects of TMZ on myocardial fibrosis by downregulating CTGF.

A comparative study between angiotensin receptor neprilysin inhibitor (thiorphan/irbesartan) with each of nitrate and carvedilol in a rat model of myocardial ischemic reperfusion injury

The combined angiotensin receptor neprilysin inhibitor is a promising cardioprotective pharmacological agent. This study investigated the beneficial effects of thiorphan (TH)/irbesartan (IRB), in myocardial ischemia-reperfusion (IR) injury, compared to each of nitroglycerin and carvedilol. Male Wistar rats were divided into five groups (10 rats/group): Sham, untreated I/R, TH/IRB + IR (0.1/10 mg/kg), nitroglycerin + IR (0.2 mg/kg), and carvedilol + IR (10 mg/kg). Mean arterial blood pressure, cardiac functions and arrhythmia incidence, duration and score were assessed. Cardiac levels of creatine kinase-MB (CK-MB), oxidative stress, endothelin-1, ATP, Na⁺ /K⁺ ATPase pump activity and mitochondria complexes activities were measured. Histopathological examination, Bcl/Bax immunohistochemistry studies and electron microscopy examination of left ventricle were performed. TH/IRB preserved the cardiac functions and mitochondrial complexes activities, mitigated cardiac damage, reduced oxidative stress and arrhythmia severity, improved the histopathological changes and decreased cardiac apoptosis. TH/IRB showed a comparable effect to each of nitroglycerin and carvedilol in alleviating the IR injury consequences. TH/IRB showed significant preservation of mitochondrial complexes activity I and II compared to nitroglycerin. TH/IRB significantly increased LVdP/dtmax and decreased oxidative stress, cardiac damage and endothelin-1 along with increasing the ATP content, Na⁺ /K⁺ ATPase pump activity and mitochondrial complexes activity when compared to carvedilol. TH/IRB showed a cardioprotective effect in reducing IR injury that is comparable to each of nitroglycerin and carvedilol that could be explained in part by its ability to preserve mitochondrial function, increase ATP, decrease oxidative stress as well as endothelin 1.

Angiotensin receptor-neprilysin inhibitor (thiorphan/irbesartan) improved cardiac function in a rat model of myocardial ischemic reperfusion injury

Mitochondria-mediated apoptosis plays a critical role in myocardial ischemia reperfusion (IR) injury and causes a negative impact on cardiac efficiency and function. The combined angiotensin receptor-neprilysin inhibitor (ARNI) is a promising cardioprotective pharmacological agent that could rescue the heart from IR injury. This study investigated the cardioprotective effect of thiorphan (TH) in combination with three different doses of irbesartan (IRB) on myocardial IR injury and detected the most effective dose combination. Male Wistar rats were used and divided into five groups (10 rats/group): (I) Sham, (II) ischemia-reperfusion I/R, (III) TH/IRB + IR (0.1/5 mg/kg), (IV) TH/IRB + IR (0.1/10 mg/kg), and (V) TH/IRB + IR (0.1/15 mg/kg) groups. Thiorphan and irbesartan were injected intraperitoneally 15 min before IR induction. Mean arterial blood pressure, left ventricular end diastolic pressure (LVEDP), left ventricular maximum rate of pressure (LVdp/dt_max ), and cardiac levels of creatine kinase-MB, malondialdehyde, superoxide dismutase, and endothelin-1 were measured. Cardiac mitochondria complexes activities, histopathological examination of myocardial tissues, immunohistochemistry studies for myocardial apoptosis (Bax and Bcl-2), and electron microscopy examination of left ventricle were performed. TH/IRB combination preserved cardiac functions and mitochondria complex activities and mitigated cardiac damage, oxidative stress, and apoptosis following IR. Also, there was an evident improvement in histopathological changes and electron microscopy examination of left ventricle compared with I/R group. TH/IRB in a dose of 0.1/10 mg/kg showed significant improvement compared with the other treated groups. Thiorphan/irbesartan improved cardiac functions following IR injury. This could be explained by the reported improvement of mitochondria complex activities and reduction of oxidative stress, endothelin-1, and apoptosis.

Fasudil inhibits hepatic artery spasm by repressing the YAP/ERK/ ETA/ETB signaling pathway via inhibiting ROCK activation

OBJECTIVE

To explore the effect of Fasudil on HA spasm and its underlying mechanism.

METHODS

Rabbits were divided into Sham, Fasudil, and Model groups for experiments. Fasudil was injected into the left medial lobe of the rabbit liver using a 16G lumbar puncture needle through the laparotomic route. The spasm model was established by inserting the catheter sheath into the femoral arteries of rabbits, followed by celiac artery angiography and left HA catheterization with a micro-catheter. Next, the GSE60887 and GSE37924 datasets concerning Fasudil treatment were analyzed. Moreover, immunofluorescence staining was conducted for YAP1 and α-SMA. Finally, Western blotting was performed to examine the expressions of YAP1, ROCK, ERK1/2, ETA, and ETB.

RESULTS

Fasudil could relieve HA spasm. The Go and KEGG pathway analyses revealed that the MAPK signaling pathway and the Hippo signaling pathway were enriched in vasospasm. Besides, GSEA revealed that ROCK was functionally enriched in the MAPK and Hippo signaling pathways. Co-expression analysis revealed that MAPK1 was significantly correlated with YAP1 and MYC, and YAP1 was significantly correlated with ETA and ETB. It was manifested in the results of immunofluorescence staining that the YAP1-positive fluorescence area was significantly decreased after Fasudil treatment. Moreover, Western blotting results showed that Fasudil decreased the expressions of YAP1, RhoA, ROCK, ETA, ETB, and p-ERK1/2. In addition, in-vitro Western blotting revealed that Fasudil suppressed the YAP/ERK/ETA/ETB signaling pathway in the case of HA spasm by inhibiting ROCK activation.

CONCLUSIONS

Fasudil ameliorates HA spasm through suppressing the YAP/ERK/ETA/ETB signaling pathway and the ROCK activation.

Sex-Specific Effects of Prenatal Hypoxia on the Cardiac Endothelin System in Adult Offspring

Fetal hypoxia, a major consequence of complicated pregnancies, impairs offspring cardiac tolerance to ischemia/reperfusion (I/R) insult, however, the mechanisms remain unknown. Endothelin-1 (ET-1) signaling through the endothelin A receptors (ET_A) is associated with cardiac dysfunction. We hypothesized that prenatal hypoxia exacerbates cardiac susceptibility to I/R via increased ET-1 and ET_A levels, while ET_A inhibition ameliorates this. Pregnant Sprague-Dawley rats were exposed to normoxia (21% O₂) or hypoxia (11% O₂) on gestational days 15-21. Offspring were aged to 4 months, and hearts were aerobically perfused or subjected to ex vivo I/R, with or without pre-infusion with an ET_A antagonist (ABT-627). ET-1 levels were assessed with ELISA in aerobically perfused and post-I/R left ventricles (LV). ET_A and ET_B levels were assessed by Western blotting in non-perfused LV. As hypothesized, ABT-627 infusion tended to improve post-I/R recovery in hypoxic females (p=0.0528), however, surprisingly, ABT-627 prevented post-I/R recovery only in the hypoxic males (p<0.001). ET-1 levels were increased in post-I/R LV in both sexes regardless of the prenatal exposure (p<0.01). ET_A expression was similar among all groups, while ET_B (isoform C) levels were decreased in prenatally hypoxic females (p<0.05). In prenatally hypoxic males, ET_A signaling may be essential for tolerance to I/R, while in prenatally hypoxic females, ET_A may contribute to cardiac dysfunction. Our data illustrate that understanding the prenatal history has critical implications for treatment strategies in adult chronic diseases.

Effect of Ramipril on Endothelin-1 Expression in Myocardial Tissue at Wistar Rats Induced Myocardial Infarction

BACKGROUND: Acute myocardial infarction occurs due to a sudden decrease in coronary blood flow caused by coronary artery embolism, coronary dissection, or coronary vasospasm. The Endothelin-1 (ET-1) is the most potent endogenous vasoconstrictor; it is synthesized and released from vascular and endocardial endothelial cells and myocytes. The action of ET-1 induces endothelial dysfunction in the coronary circulation through several mechanisms, such as reduced NO pathway activity, increased oxidative stress and inflammation, and interference with glucose and lipid metabolism. Ramipril is one of the angiotensin-converting enzyme inhibitors (ACE-I) that can reduce the formation of ET-1 by enhancing the NO expression. NO can down-regulate the ET-1 secretion through soluble guanylate cyclase activation and increased cellular generation of cGMP. AIM: This study aimed to investigate the effect of Ramipril on ET-1 expression in rats-induced myocardial infarction. METHODS: Six-week-old male Wistar rats were randomly allocated into three groups: negative control, positive control was given NaCl 0.9% and treatment group treated with ramipril 3 mg/kg/day orally for 7 days. Myocardial infarction was induced in positive and treatment group by subcutaneous injection of isoproterenol, and 24 h after the last administration, rats were sacrificed to evaluate the relative expression of ET-1 using the real-time polymerase chain reaction and 2-ΔΔCt method. RESULTS: The average expression for the negative control was 0.0098, positive control was 0.0136 and treatment group was 0.0118, with p = 0.210 (p > 0.05). CONCLUSION: Our data suggest that there is no difference between groups for the relative expression of ET-1.

Cardiovascular Effects of Snake Toxins: Cardiotoxicity and Cardioprotection

Snake venoms, as complex mixtures of peptides and proteins, affect various vital systems of the organism. One of the main targets of the toxic components from snake venoms is the cardiovascular system. Venom proteins and peptides can act in different ways, exhibiting either cardiotoxic or cardioprotective effects. The principal classes of these compounds are cobra cardiotoxins, phospholipases A2, and natriuretic, as well as bradykinin-potentiating peptides. There is another group of proteins capable of enhancing angiogenesis, which include, e.g., vascular endothelial growth factors possessing hypotensive and cardioprotective activities. Venom proteins and peptides exhibiting cardiotropic and vasoactive effects are promising candidates for the design of new drugs capable of preventing or constricting the development of pathological processes in cardiovascular diseases, which are currently the leading cause of death worldwide. For example, a bradykinin-potentiating peptide from Bothrops jararaca snake venom was the first snake venom compound used to create the widely used antihypertensive drugs captopril and enalapril. In this paper, we review the current state of research on snake venom components affecting the cardiovascular system and analyse the mechanisms of physiological action of these toxins and the prospects for their medical application.

Unraveling the Mystery of Cold Stress-Induced Myocardial Injury

Exposure to low ambient temperature imposes great challenge to human health. Epidemiological evidence has noted significantly elevated emergency admission and mortality rate in cold climate in many regions, in particular, adverse events in cardiovascular system. Cold stress is becoming one of the important risk factors for cardiovascular death. Through recent advance in echocardiography and myocardial histological techniques, both clinical and experimental experiments have unveiled that cold stress triggers a variety of pathological and pathophysiological injuries, including ventricular wall thickening, cardiac hypertrophy, elevated blood pressure, decreased cardiac function, and myocardial interstitial fibrosis. In order to examine the potential mechanism of action behind cold stress-induced cardiovascular anomalies, ample biochemical and molecular biological experiments have been conducted to denote a role for mitochondrial injury, intracellular Ca²⁺ dysregulation, generation of reactive oxygen species (ROS) and other superoxide, altered gene and protein profiles for apoptosis and autophagy, and increased adrenergic receptor sensitivity in cold stress-induced cardiovascular anomalies. These findings suggest that cold stress may damage the myocardium through mitochondrial injury, apoptosis, autophagy, metabolism, oxidative stress, and neuroendocrine pathways. Although the precise nature remains elusive for cold stress-induced cardiovascular dysfunction, endothelin (ET-_A) receptor, endoplasmic reticulum (ER) stress, transient receptor potential vanilloid, mitochondrial-related protein including NRFs and UCP-2, ROS, Nrf2-Keap1 signaling pathway, Bcl-2/Bax, and lipoprotein lipase (LPL) signaling may all play a pivotal role. For myocardial injury evoked by cold stress, more comprehensive and in-depth mechanisms are warranted to better define the potential therapeutic options for cold stress-associated cardiovascular diseases.

China Tongxinluo Study for myocardial protection in patients with Acute Myocardial Infarction (CTS-AMI): Rationale and design of a randomized, double-blind, placebo-controlled, multicenter clinical trial

Acute ST-segment elevation myocardial infarction (STEMI) remains a serious life-threatening event. Despite coronary revascularization, patients might still suffer from poor outcomes caused by myocardial no-reflow and ischemic/reperfusion injury. Tongxinluo (TXL), a traditional Chinese medicine, has been preliminarily demonstrated to reduce myocardial no-reflow and ischemic/reperfusion injury. We further hypothesize that TXL treatment is also effective in reducing clinical end points for the patients with STEMI.

Methods and results

The CTS-AMI trial is a prospective, randomized, double-blind, placebo-controlled, multicenter clinical study in China. An estimated 3,796 eligible patients with STEMI from about 120 centers are randomized 1:1 ratio to TXL or placebo groups. All enrolled patients are orally administrated a loading dose of 8 capsules of TXL or placebo together with dual antiplatelet agents on admission followed by 4 capsules 3 times a day until 12 months. The primary end point is 30-day major adverse cardiovascular and cerebrovascular events, a composite of cardiac death, myocardial reinfarction, emergency coronary revascularization, and stroke. Secondary end points include each component of the primary end point, 1-year major adverse cardiovascular and cerebrovascular events, and other efficacy and safety parameters.

Conclusions

Results of CTS-AMI trial will determine the clinical efficacy and safety of traditional Chinese medicine TXL capsule in the treatment of STEMI patients in the reperfusion era.

MiR-302a-3p aggravates myocardial ischemia-reperfusion injury by suppressing mitophagy via targeting FOXO3

OBJECTIVE

This study aimed to investigate whether the protection of miR-302a-3p in myocardial ischemia-reperfusion injury (MIRI) is mediated through the suppression of mitophagy.

METHODS

We constructed a mouse I/R model in vivo by the ligation of left anterior descending coronary artery for 45 min followed by 2 h reperfusion, and an in vitro model by treating mouse cardiomyocytes with hypoxia-reoxygenation (H/R). Knockdown experiments were then performed in vivo and in vitro to determine the effects of miR-302a-3p knockdown on the mitophagy, mitochondrial dysfunction and oxidative stress and apoptosis. The potential targets of miR-302a-3p were further studied by bioinformatics analysis, luciferase assays, quantitative real-time PCR and western blotting.

RESULTS

MiR-302a-3p expression was significantly upregulated in mice subjected to MIRI and in H/R-treated mouse cardiomyocytes. Functional analyses demonstrated that inhibition of miR-302a-3p protected cardiac tissues against I/R-induced apoptosis and mitophagy, mitochondrial damage and mitochondrial oxidative stress. Furthermore, FOXO3 was identified as the direct target of miR-302a-3p. Mechanistically, knockdown of FOXO3 partially reversed the cardioprotective effects of miR-302a-3p inhibitor.

CONCLUSION

Our study suggested that inhibition of miR-302a-3p promoted mitochondrial autophagy and inhibited oxidative stress by targeting FOXO3 to suppress myocardial apoptosis, representing a potential target for MIRI treatment.

Heart‑lung crosstalk in pulmonary arterial hypertension following myocardial infarction (Review)

Left heart disease is the main cause of clinical pulmonary arterial hypertension (PAH). Common types of left heart disease that result in PAH include heart failure, left ventricular systolic dysfunction, left ventricular diastolic dysfunction and valvular disease. It is currently believed that mechanical pressure caused by high pulmonary venous pressure is the main cause of myocardial infarction (MI) in individuals with ischemic cardiomyopathy and left ventricular systolic dysfunction. In the presence of decreased cardiac function, vascular remodeling of pulmonary vessels in response to long-term stimulation by high pressure in turn leads to exacerbation of PAH. However, the underlying pathological mechanisms remain unclear. Elucidating the association between the development of MI and PAH may lead to a better understanding of potential risk factors and better disease treatment. In this article, the pathophysiological effects of multiple systems in individuals with MI and PAH were reviewed in order to provide a general perspective on various potential interactions between cardiomyocytes and pulmonary vascular cells.

Secondhand cigarette smoke induces increased expression of contractile endothelin receptors in rat coronary arteries via a MEK1/2 sensitive mechanism

OBJECTIVES

Cigarette smoke, a strong risk factor for cardiovascular diseases, upregulates contractile endothelin (ET) receptors in coronary arteries. The present study examined the effects of second hand cigarette smoke exposure on the contractile endothelin receptors and the role of the MEK1/2 pathway in rat coronary arteries. Design: Rats were exposed to secondhand smoke (SHS) for 8 weeks followed by intraperitoneal injection of a MEK1/2 inhibitor, U0126 daily for another 4 weeks. Contractile responses of isolated coronary arteries were recorded by a sensitive wire myograph. The receptor protein expression levels were examined by Western blotting. Results: The results showed that SHS in vivo caused increased expression of ET receptors ET_A and ET_B, and that the MEK1/2 blocker U0126 significantly reversed SHS exposure-increased ET_A-mediated contractile responses and protein levels. Similar alterations were observed in ET_B receptors. U0126 showed dose-dependent effects on SHS-induced response on contractile property and protein levels of the ET_B receptor. However, only the higher dose U0126 (15 mg/kg) had inhibitory effects on the ET_A receptor. Conclusions: Taken together, our data show that SHS increases contractile ET receptors and MEK1/2 pathway inhibitor offsets SHS exposure-induced ET_A and ET_B receptor upregulation in rat coronary arteries.

MiR-25 exerts cardioprotective effect in a rat model of myocardial ischemia-reperfusion injury by targeting high-mobility group box 1

BACKGROUND

We previously confirmed the targeting of high-mobility group box 1 (HMGB1) by miR-25. This project aims to further investigate whether miR-25 improves myocardial ischemia-reperfusion injury (IRI) in vivo by targeting HMGB1.

METHODS

A rat model of myocardial IRI was established by the ligation of the left anterior descending coronary artery for 45 minutes followed by 2, 4, or 6 hours reperfusion. The expression of miR-25, HMGB1, and apoptosis-related proteins in the myocardium was determined by quantitative real-time polymerase chain reaction (PCR) and western blotting. The activities of myocardial enzymes and the release of inflammatory cytokines were evaluated by enzyme-linked immunosorbent assay. Evans blue/triphenyltetrazolium chloride double staining was performed to assess infarct size. Myocardial apoptosis was detected by terminal deoxynucleotidyl transferase dUTP nick end labeling staining.

RESULTS

MiR-25 expression was significantly downregulated, while HMGB1 was highly expressed at the mRNA and protein levels in myocardial tissues after induction of the IRI model. MiR-25 agomir administration suppressed the expression of HMGB1 in myocardial tissues. Furthermore, administration of both miR-25 agomir and lentivirus-mediated short hairpin RNA (shRNA) interference targeting HMGB1 sh-HMGB1 resulted in reduced serum myocardial enzyme activities, cytokine secretion, and myocardial apoptosis during myocardial IRI.

CONCLUSION

MiR-25 mitigated myocardial IRI-induced damage by targeting HMGB1.

miR-30c-5p Reduces Renal Ischemia-Reperfusion Involving Macrophage

Background

Ischemia-reperfusion (I/R) leads to kidney injury. Renal I/R frequently occurs in kidney transplantations and acute kidney injuries. Recent studies reported that miR-30 stimulated immune responses and reductions in renal I/R related to anti-inflammation. Our study investigated the effects of miR-30c-5p on renal I/R and the relationship among miR-30c-5p, renal I/R, and macrophages.

Material/Methods

Sprague Dawley rats received intravenous tail injections of miR-30c-5p agomir. Then a renal I/R model were established by removing the left kidney and clamping the right renal artery. Serum creatinine (Cr) was analyzed using a serum Cr assay kit, and serum neutrophil gelatinase associated lipocalin (NGAL) was measured using a NGAL ELISA (enzyme-linked immunosorbent assay) kit. Rat kidney tissues were analyzed using hematoxylin and eosin staining. THP-1 cells treated with miR-30c-5p agomir and miR-30c-5p antagomir were measured with quantitative reverse transcription-polymerase chain reaction. Protein levels were analyzed by western blot.

Results

MiR-30c-5p agomir reduced serum Cr, serum NGAL, and renal I/R injury. MiR-30c-5p agomir inhibited the expression of CD86 (M1 macrophage marker), inducible nitric oxide synthase (iNOS), and tumor necrosis factor-alpha (TNF-α) and promoted the expression of CD206 (M2 macrophage marker), interleukin (IL)-4, and IL-10 in rat kidneys. MiR-30c-5p agomir reduced the expression of CD86 and iNOS, and increased the expression of CD206 and IL-10 in THP-1 cells.

Conclusions

We preliminarily demonstrated that miR-30c-5p agomir might decrease renal I/R through transformation of M1 macrophages to M2 macrophages and resulted in changes in inflammatory cytokines.

Expression of endothelin type B receptors in uterine artery smooth muscle cells from pregnant Guinea pigs

INTRODUCTION

It is well established that upregulation of endothelin type B (ET_B) receptors in vascular smooth muscle cells plays a role in pathophysiological artery remodeling as response to ischemia and atherosclerosis. This study aimed to investigate the ET_B receptors function and localization under normal physiological remodeling. Specifically, in the guinea pig uterine arteries during pregnancy.

METHODS

Uterine artery contractility was assessed with sarafotoxin 6c and endothelin-1 in wire-myography in uterine arteries from non-pregnant and pregnant guinea pigs at gestational day 37 ± 5. Localization of ET_B receptors, proliferation marker Ki-67, and SMC differentiation marker SM22α in uterine arteries were investigated with immunohistochemistry.

RESULTS

Uterine arteries from pregnant guinea pigs showed significantly increased ET_B receptor-mediated vasoconstriction compared to uterine arteries from non-pregnant and to coronary arteries from pregnant guinea pigs (p < 0.001), suggesting that ET_B-receptor upregulation in uterine artery SMCs is a normal physiological mechanism taking place during remodeling. Furthermore, uterine arteries from pregnant guinea pigs showed enhanced expression of ET_B receptors, high density of Ki-67 positive SMCs and sparse SM22α staining in SMCs localized in the outer layer of the vessel wall.

DISCUSSION

Our results suggest that ET_B receptors are expressed in dedifferentiated proliferating SMCs of uterine arteries in pregnant guinea pigs. This study provides novel insight into the function and expression of ET_B receptors in uterine vascular remodeling during pregnancy.

Role of pannexin and adenosine triphosphate (ATP) following myocardial ischemia/reperfusion

OBJECTIVES

The purinergic system has not been investigated in detail following ischemia/reperfusion (I/R) injury in the heart. In the present study, we focus on both release and response to extracellular adenosine triphosphate (ATP). Pannexin (Panx) channels have been shown to be involved in ATP release from myocytes and can activate P2X1 and P2Y2 receptors on the coronary artery.

DESIGN

We applied a well-characterized I/R model in rats, with 24 hours of reperfusion. Panx expression in the myocardial tissue was measured with quantitative polymerase chain reaction (qPCR) and flow cytometry. ATP release was detected in situ using luminescence and the vascular response to nucleotides determined in a wire myograph.

RESULTS

Here, we show that Panx expression is increased after experimental myocardial I/R, leading to an increase in extracellular ATP release, which could be inhibited by probenecid. Functional studies revealed that the P2Y2 receptor-dependent contraction is reduced in the coronary artery after I/R, which might be a response to the increased ATP levels.

CONCLUSION

We, therefore, conclude that the regulation of the arterial purinergic system minimizes coronary contractions following ischemia.

Autoimmune disease mouse model exhibits pulmonary arterial hypertension

Background

Pulmonary arterial hypertension is often associated with connective tissue disease. Although there are some animal models of pulmonary hypertension, an autoimmune disease-based model has not yet been reported. MRL/lpr mice, which have hypergammaglobulinemia, produce various autoimmune antibodies, and develop vasculitis and nephritis spontaneously. However, little is known about pulmonary circulation in these mice. In the present study, we examined the pulmonary arterial pressure in MRL/lpr mice.

Methods and results

We used female MRL/lpr mice aged between 12 and 14 weeks. Fluorescent immunostaining showed that there was no deposition of immunoglobulin or C3 in the lung tissue of the MRL/lpr mice. Elevation of interferon-γ and interleukin-6 was recognized in the lung tissue of the MRL/lpr mice. Right ventricular systolic pressure, Fulton index and the ratio of right ventricular weight to body weight in the MRL/lpr mice were significantly higher than those in wild type mice with same background (C57BL/6). The medial smooth muscle area and the proportion of muscularized vessels in the lung tissue of the MRL/lpr mice were larger than those of the C57BL/6 mice. Western blot analysis demonstrated markedly elevated levels of prepro-endothelin-1 and survivin as well as decreased endothelial nitric oxide synthase phosphorylation in the lung tissue of the MRL/lpr mice. Terminal deoxynucleotidyl-transferase-mediated dUTP nick end-labeling assay showed the resistance against apoptosis of pulmonary arterial smooth muscle cells in the MRL/lpr mice.

Conclusion

We showed that MRL/lpr mice were complicated with pulmonary hypertension. MRL/lpr mice appeared to be a useful model for studying the mechanism of pulmonary hypertension associated with connective tissue diseases.

Changes in vasodilation following myocardial ischemia/reperfusion in rats

BACKGROUND

Blockage of a coronary artery, usually caused by arteriosclerosis, can lead to life threatening acute myocardial infarction. Opening with PCI (percutaneous coronary intervention), may be lifesaving, but reperfusion might exacerbate the cellular damage, and changes in the endothelium are believed to be involved in this worsened outcome.

AIM

The aim of the present study was to compare endothelial dependent and independent vasodilatory effect after experimental myocardial ischemia/reperfusion (I/R).

METHODS

A well-established rat model of myocardial ischemia with 24 h of reperfusion was applied, followed by a study in a wire myograph.

RESULTS

Endothelial NO dependent relaxation in response to carbachol, was sensitive to arterial depolarization, and was unaffected by I/R. In contrast, endothelial NO dependent ADPβS signalling, which was not sensitive to arterial depolarization, was significantly reduced after I/R. Following I/R, an H₂O₂ dependent EDH induced dilation appears in response to both of the above agonists. In addition, calcitonin gene-related peptide (CGRP) induced vasodilation was reduced.

CONCLUSION

These data show that NO dependent ADPβS induced dilation is reduced after I/R. However, there is some compensation by released H₂O₂ causing an EDH. Combined with a loss of maximal dilation in response to CGRP, the reduced vasodilation could be an important factor in understanding the exacerbated damage after I/R.

Aerobic exercise combined with huwentoxin-I mitigates chronic cerebral ischemia injury

Ca²⁺ channel blockers have been shown to protect neurons from ischemia, and aerobic exercise has significant protective effects on a variety of chronic diseases. The present study injected huwentoxin-I (HWTX-I), a spider peptide toxin that blocks Ca²⁺ channels, into the caudal vein of a chronic cerebral ischemia mouse model, once every 2 days, for a total of 15 injections. During this time, a subgroup of mice was subjected to treadmill exercise for 5 weeks. Results showed amelioration of cortical injury and improved neurological function in mice with chronic cerebral ischemia in the HWTX-I + aerobic exercise group. The combined effects of HWTX-I and exercise were superior to HWTX-I or aerobic exercise alone. HWTX-I effectively activated the Notch signal transduction pathway in brain tissue. Aerobic exercise up-regulated synaptophysin mRNA expression. These results demonstrated that aerobic exercise, in combination with HWTX-I, effectively relieved neuronal injury induced by chronic cerebral ischemia via the Notch signaling pathway and promoting synaptic regeneration.