Topical Clonidine Accelerates Cutaneous Wound Healing in Diabetic Rats by Regulating the Expression of Related Cytokine Signaling.

Based on the analgesic and anti-inflammatory effects of clonidine in previous studies, we hypothesized that clonidine could accelerate wound healing in rats by regulating the expression of related cytokines. In this study, the wound healing effect of clonidine was evaluated using an excision wound model in diabetic rats and a HaCaT cell model. The wounds were treated daily with topical clonidine. The results analyzed by ImageJ2 software show that the wounds of the rats that were treated with 15 ng/mL clonidine recovered faster, and the wound size was also significantly reduced compared to the control group. Western blot assays determined that clonidine induced an increase in the expression of vascular growth factors, namely, Ang-1, Ang-2, and VEGF. Moreover, clonidine demonstrated a rescuing effect on JAK2 within the JAK/STAT pathway by inhibiting SOCS3 expression, leading to decreased SOCS3 levels and increased expression of JAK2 and phospho-STAT3. Histopathological analysis revealed that clonidine promoted complete epithelial repair and minimized inflammation in skin tissue. Additionally, clonidine stimulated HaCaT cell proliferation in vitro and enhanced cellular energy levels in the presence of AGEs. In conclusion, clonidine promoted vascular growth and wound healing by stimulating the expression of cytokines that are beneficial for wound healing.

Soluble Dipeptidyl Peptidase-4 Induces Fibroblast Activation Through Proteinase-Activated Receptor-2.

Fibroblasts are the chief secretory cells of the extracellular matrix (ECM) responsible for basal deposition and degradation of the ECM under normal conditions. During stress, fibroblasts undergo continuous activation, which is defined as the differentiation of fibroblasts into myofibroblasts, a cell type with an elevated capacity for secreting ECM proteins. Dipeptidyl peptidase-4 (DPP4) is a ubiquitously expressed transmembrane glycoprotein and exerts effects that are both dependent and independent of its enzymatic activity. DPP4 has been demonstrated to define fibroblast populations in human skin biopsies of systemic sclerosis. Shedding of DPP4 from different tissues into the circulation appears to be involved in the pathogenesis of the diseases. The mechanism underlying soluble DPP4-induced dermal fibrosis has not been clearly determined. The effects of DPP4 on murine 3T3 fibroblasts and human dermal fibroblasts were evaluated by measuring the expression of fibrotic proteins, such as α-SMA and collagen. Soluble DPP4 stimulated the activation of fibroblasts in a dose-dependent manner by activating nuclear factor-kappa B (NF-κB) and suppressor of mothers against decapentaplegic (SMAD) signaling. Blocking proteinase-activated receptor-2 (PAR2) abrogated the DPP4-induced activation of NF-κB and SMAD and expression of fibrosis-associated proteins in fibroblasts. Linagliptin, a clinically available DPP4 inhibitor, was observed to abrogate the soluble DPP4-induced expression of fibrotic proteins. This study demonstrated the mechanism underlying soluble DPP4, which activated NF-κB and SMAD signaling through PAR2, leading to fibroblast activation. Our data extend the current view of soluble DPP4. Elevated levels of circulating soluble DPP4 may contribute to one of the mediators that induce dermal fibrosis in patients.

Reduction of blood pressure elevation by losartan in spontaneously hypertensive rats through suppression of LARG expression in vascular smooth muscle cells.

BACKGROUND/PURPOSE: This study sought to elucidate the mechanism by which losartan inhibits blood pressure (BP) elevation in spontaneously hypertensive rats (SHRs). METHODS: Four-week-old Wistar-Kyoto (WKY) rats and SHRs were either treated with losartan (20 mg/kg/day) for 8 weeks or served as untreated controls. BP was measured by the tail-cuff method. At 12 weeks, isometric contraction of the aortic rings of the rats was evaluated with a force transducer and recorder. The mRNA and protein levels of the target Rho guanine nucleotide exchange factors (RhoGEFs), and the extent of myosin phosphatase target subunit 1 (MYPT-1) phosphorylation in the aorta, were determined using quantitative real-time polymerase chain reaction (qPCR) assay and Western blot analysis. RESULTS: The BP of the four-week-old SHRs did not differ from that of the age-matched WKY rats, whereas the BP of the twelve-week-old control group SHRs was higher than that of the control group WKY rats. Losartan treatment, however, inhibited BP elevation in both rat strains, doing so to a greater extent in the treatment group SHRs. The contractile force in response to angiotensin II of the aortic rings from the SHRs treated with losartan was significantly lower than that of the aortic rings from the non-treated SHRs. The protein expression of leukemia-associated RhoGEF (LARG) was significantly higher in the non-treated SHRs compared to the non-treated WKY rats. CONCLUSION: The study results showed that the reduction of BP elevation by losartan in SHRs occurs through the suppression of LARG expression and MYPT-1 phosphorylation in vascular smooth muscle cells.

A novel isoquinoline derivative exhibits anti-inflammatory properties and improves the outcomes of endotoxemia.

BACKGROUND: Sepsis initiates an inflammatory response that causes widespread injury, and candidates for related myocardial depressant factors include cytokines and nitric oxide (NO). Nuclear factor kappa-B (NF-κB) stimulated by toll-like receptor 4 activation in sepsis mediates the transcription of multiple proinflammatory genes. These inflammatory mediators can cause myocardial dysfunction, which may deteriorate sepsis outcomes. To address this risk, we investigated the potential beneficial effects of a novel isoquinolines derivative, CYY054c, in LPS-induced inflammatory response leading to endotoxemia. METHODS: The effects of CYY054c on cytokine and inflammatory-related protein production were evaluated in lipopolysaccharide (LPS)-stimulated macrophages. To determine whether CYY054c alleviates inflammatory storm-induced myocardial dysfunction in vivo, LPS was injected in rats, and cardiac function was measured by a pressure-volume loop. RESULTS: CYY054c inhibited LPS-induced NF-κB expression in macrophages and reduced the release of tumor necrosis factor-alpha (TNF-α), interleukin-1ß (IL-1ß), and interleukin-6 (IL-6), as well as the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). In the animal studies, CYY054c alleviated LPS-upregulated plasma TNF-α, IL-1ß, IL-6, and NO concentrations, as well as cardiac monocyte chemotactic protein-1, iNOS, and COX-2 expression in rats, contributing to the improvement of cardiac function during endotoxemia. CONCLUSIONS: The reduction of NF-κB-mediated inflammatory mediators and the maintenance of hemodynamic performance by CYY054c improved the outcomes during endotoxemia. CYY054c may be a potential therapeutic agent for sepsis.

Single allele Lmbrd1 knockout results in cardiac hypertrophy.

BACKGROUND/PURPOSE: LMBD1 protein, a type IV-B plasma membrane protein possessing nine putative trans-membrane domains, was previously demonstrated at cellular level to play a critical part in the signaling cascade of insulin receptor through its involvement in regulating clathrin-mediated endocytosis. However, at physiological level, the significance of LMBD1 protein in cardiac development remains unclear. METHODS: To understand the role of Lmbrd1 gene involved in the cardiac function, heterozygous knockout mice were used as an animal model system. The pathological outcomes were analyzed by micro-positron emission tomography, ECG acquisition, cardiac ultrasound, and immunohistochemistry. RESULTS: By studying the heterozygous knockout of Lmbrd1 (Lmbrd1+/-), we discovered that lack of Lmbrd1 not only resulted in the increase of cardiac-glucose uptake, pathological consequences were also observed. Here, we have distinguished that Lmbrd1+/- is sufficient in causing cardiac diseases through a pathway independent of the recessive vitamin B12 cblF cobalamin transport defect. Lmbrd1+/- mice exhibited an increase in myocardial glucose uptake and insulin receptor signaling that is insensitive to the administration of additional insulin. Pathological symptoms such as cardiac hypertrophy, ventricular tissue fibrosis, along with the increase of heart rate and cardiac muscle contractility were observed. As Lmbrd1+/- mice aged, the decrease in ejection fraction and fraction shortening showed signs of ventricular function deterioration. CONCLUSION: The results suggested that Lmbrd1 gene not only plays a significant role in mediating the energy homeostasis in cardiac tissue, it may also be a key factor in the regulation of cardiac function in mice.

Electronegative LDL-mediated cardiac electrical remodeling in a rat model of chronic kidney disease.

The mechanisms underlying chronic kidney disease (CKD)-associated higher risks for life-threatening ventricular tachyarrhythmias remain poorly understood. In rats subjected to unilateral nephrectomy (UNx), we examined cardiac electrophysiological remodeling and relevant mechanisms predisposing to ventricular arrhythmias. Adult male Sprague-Dawley rats underwent UNx (n = 6) or sham (n = 6) operations. Eight weeks later, the UNx group had higher serum blood urea nitrogen and creatinine levels and a longer electrocardiographic QTc interval than did the sham group. Patch-clamp studies revealed epicardial (EPI)-predominant prolongation of the action potential duration (APD) at 50% and 90% repolarization in UNx EPI cardiomyocytes compared to sham EPI cardiomyocytes. A significant reduction of the transient outward potassium current (Ito) in EPI but not in endocardial (ENDO) cardiomyocytes of UNx rats led to a decreased transmural gradient of Ito. The reduction of Ito currents in UNx EPI cardiomyocytes was secondary to downregulation of KChIP2 but not Kv4.2, Kv4.3, and Kv1.4 protein expression. Incubation of plasma electronegative low-density lipoprotein (LDL) from UNx rats with normal EPI and ENDO cardiomyocytes recapitulated the electrophysiological phenotype of UNx rats. In conclusion, CKD disrupts the physiological transmural gradient of Ito via downregulation of KChIP2 proteins in the EPI region, which may promote susceptibility to ventricular tachyarrhythmias. Electronegative LDL may underlie downregulation of KChIP2 in CKD.

Aldosterone Induces Tissue Inhibitor of Metalloproteinases-1 Expression and Further Contributes to Collagen Accumulation: From Clinical to Bench Studies.

Aldosterone induces myocardial fibrosis. Tissue inhibitor of metalloproteinases-1 (TIMP-1) is a key factor of myocardial fibrosis. This study tested the hypothesis that aldosterone induces TIMP-1 expression and contributes to the fibrotic process. We prospectively enrolled 54 patients with primary aldosteronism, and measured plasma TIMP-1 and echocardiographic parameters. In the cell study, we investigated the possible molecular mechanism by which aldosterone induces TIMP-1 secretion and the effects on collagen accumulation. In the animal study, we measured serum TIMP-1 levels, cardiac TIMP-1 levels, and cardiac structure in an aldosterone infusion mouse model using implantation of aldosterone pellets. In patients with primary aldosteronism, plasma TIMP-1 was correlated with 24-hour urinary aldosterone, left ventricular mass, and impairment of left ventricular diastolic function. In human cardiac fibroblasts, TIMP-1 protein and mRNA expressions were significantly increased by aldosterone through the glucocorticoid receptor/PI3K/Akt/nuclear factor-κB pathway. TIMP-1 small-interfering RNA significantly reduced aldosterone-induced collagen accumulation, and aldosterone did not alter the levels of collagen1a1 or matrix metalloproteinase-1 mRNA. The aldosterone-induced TIMP-1 expression was inversely related to matrix metalloproteinase-1 activity. Furthermore, in the animal model, the serum and cardiac levels of TIMP-1 were significantly elevated in the mice that received aldosterone infusion. This elevation was blocked by RU-486 but not by eplerenone, suggesting that the effect was through glucocorticoid receptors. In a long-term aldosterone infusion model, serum TIMP-1 was associated with serum aldosterone level, cardiac structure, and fibrosis. In conclusion, aldosterone induced TIMP-1 expression in vivo and in vitro. This increased TIMP-1 expression resulted in enhanced collagen accumulation via the suppression of matrix metalloproteinase-1 activity.

Modification of Caffeic Acid with Pyrrolidine Enhances Antioxidant Ability by Activating AKT/HO-1 Pathway in Heart.

Overproduction of free radicals during ischemia/reperfusion (I/R) injury leads to an interest in using antioxidant therapy. Activating an endogenous antioxidant signaling pathway is more important due to the fact that the free radical scavenging behavior in vitro does not always correlate with a cytoprotection effect in vivo. Caffeic acid (CA), an antioxidant, is a major phenolic constituent in nature. Pyrrolidinyl caffeamide (PLCA), a derivative of CA, was compared with CA for their antioxidant and cytoprotective effects. Our results indicate that CA and PLCA exert the same ability to scavenge DPPH in vitro. In response to myocardial I/R stress, PLCA was shown to attenuate lipid peroxydation and troponin release more than CA. These responses were accompanied with a prominent elevation in AKT and HO-1 expression and a preservation of mnSOD expression and catalase activity. PLCA also improved cell viability and alleviated the intracellular ROS level more than CA in cardiomyocytes exposed to H2O2. When inhibiting the AKT or HO-1 pathways, PLCA lost its ability to recover mnSOD expression and catalase activity to counteract with oxidative stress, suggesting AKT/HO-1 pathway activation by PLCA plays an important role. In addition, inhibition of AKT signaling further abolished HO-1 activity, while inhibition of HO-1 signaling attenuated AKT expression, indicating cross-talk between the AKT and HO-1 pathways. These protective effects may contribute to the cardiac function improvement by PLCA. These findings provide new insight into therapeutic approaches using a modified natural compound against oxidative stress from myocardial injuries.

A Model of Cardiac Remodeling Through Constriction of the Abdominal Aorta in Rats.

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and fluid retention. Changes in myocardial structure, electrical conduction, and energy metabolism develop with heart failure, leading to contractile dysfunction, increased risk of arrhythmias, and sudden death. Hypertensive heart disease is one of the key contributing factors of cardiac remodeling associated with heart failure. The most commonly-used animal model mimicking hypertensive heart disease is created via surgical interventions, such as by narrowing the aorta. Abdominal aortic constriction is a useful experimental technique to induce a pressure overload, which leads to heart failure. The surgery can be easily performed, without the need for chest opening or mechanical ventilation. Abdominal aortic constriction-induced cardiac pathology progresses gradually, making this model relevant to clinical hypertensive heart failure. Cardiac injury and remodeling can be observed 10 weeks after the surgery. The method described here provides a simple and effective approach to produce a hypertensive heart disease animal model that is suitable for studying disease mechanisms and for testing novel therapeutics.

NRIP is newly identified as a Z-disc protein, activating calmodulin signaling for skeletal muscle contraction and regeneration.

Nuclear receptor interaction protein (NRIP, also known as DCAF6 and IQWD1) is a Ca(2+)-dependent calmodulin-binding protein. In this study, we newly identify NRIP as a Z-disc protein in skeletal muscle. NRIP-knockout mice were generated and found to have reduced muscle strength, susceptibility to fatigue and impaired adaptive exercise performance. The mechanisms of NRIP-regulated muscle contraction depend on NRIP being downstream of Ca(2+) signaling, where it stimulates activation of both 'calcineurin-nuclear factor of activated T-cells, cytoplasmic 1' (CaN-NFATc1; also known as NFATC1) and calmodulin-dependent protein kinase II (CaMKII) through interaction with calmodulin (CaM), resulting in the induction of mitochondrial activity and the expression of genes encoding the slow class of myosin, and in the regulation of Ca(2+) homeostasis through the internal Ca(2+) stores of the sarcoplasmic reticulum. Moreover, NRIP-knockout mice have a delayed regenerative capacity. The amount of NRIP can be enhanced after muscle injury and is responsible for muscle regeneration, which is associated with the increased expression of myogenin, desmin and embryonic myosin heavy chain during myogenesis, as well as for myotube formation. In conclusion, NRIP is a novel Z-disc protein that is important for skeletal muscle strength and regenerative capacity.

Caffeic acid ethanolamide prevents cardiac dysfunction through sirtuin dependent cardiac bioenergetics preservation.

BACKGROUND: Cardiac oxidative stress, bioenergetics and catecholamine play major roles in heart failure progression. However, the relationships between these three dominant heart failure factors are not fully elucidated. Caffeic acid ethanolamide (CAEA), a synthesized derivative from caffeic acid that exerted antioxidative properties, was thus applied in this study to explore its effects on the pathogenesis of heart failure. RESULTS: In vitro studies in HL-1 cells exposed to isoproterenol showed an increase in cellular and mitochondria oxidative stress. Two-week isoproterenol injections into mice resulted in ventricular hypertrophy, myocardial fibrosis, elevated lipid peroxidation, cardiac adenosine triphosphate and left ventricular ejection fraction decline, suggesting oxidative stress and bioenergetics changes in catecholamine-induced heart failure. CAEA restored oxygen consumption rates and adenosine triphosphate contents. In addition, CAEA alleviated isoproterenol-induced cardiac remodeling, cardiac oxidative stress, cardiac bioenergetics and function insufficiency in mice. CAEA treatment recovered sirtuin 1 and sirtuin 3 activity, and attenuated the changes of proteins, including manganese superoxide dismutase and hypoxia-inducible factor 1-α, which are the most likely mechanisms responsible for the alleviation of isoproterenol-caused cardiac injury CONCLUSION: CAEA prevents catecholamine-induced cardiac damage and is therefore a possible new therapeutic approach for preventing heart failure progression.

Circulating tissue inhibitor of matrix metalloproteinase-1 is associated with aldosterone-induced diastolic dysfunction.

OBJECTIVE: To test if collagen markers are associated with aldosterone-induced diastolic dysfunction. BACKGROUND: Although primary aldosteronism is associated with more prominent cardiac remodeling and diastolic dysfunction, the reversibility of diastolic function is unclear. In addition, there is no known biomarker associated with aldosterone-induced diastolic dysfunction. METHODS: We enrolled 27 patients with aldosterone-producing adenoma (APA) preparing for adrenalectomy, and 27 patients with essential hypertension prospectively from October 2006 to March 2010 at a tertiary referral center. Plasma matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were measured, and echocardiography including tissue Doppler images was performed in both groups and 1 year after receiving adrenalectomy in the APA group. RESULTS: The baseline plasma TIMP-1 level (88.4 ±â€Š38.7 vs. 63.6 ±â€Š32.5 ng/ml; P = 0.014), left ventricular mass index (LVMI), and E/E' ratio (11.5 ±â€Š2.9 vs. 9.0 ±â€Š2.1; P < 0.001) were significantly higher in the APA group. The baseline plasma TIMP-1 level significantly correlated with the E/E' ratio, LVMI, interventricular septum, and left atrial diameter. The plasma MMP-2 level did not correlate with the left ventricular structure parameters, except for interventricular septum thickness. After adrenalectomy, LVMI and E/E' ratio improved significantly. The postadrenalectomy plasma TIMP-1 levels, but not MMP-2 levels, also decreased. The change of plasma TIMP-1 levels was negatively associated with the postadrenalectomy E/E' ratio after adjustment for age, sex, BMI, and mean blood pressure (ß-coefficient = - 3.6, P = 0.004). CONCLUSION: Excess of aldosterone induces cardiac diastolic dysfunction, which is reversible by adrenalectomy. TIMP-1 is associated with the aldosterone-induced diastolic dysfunction.

5-hydroxytryptamine has an endothelium-derived hyperpolarizing factor-like effect on coronary flow in isolated rat hearts.

BACKGROUND: 5-hydroxytryptamine (5-HT)-induced coronary artery responses have both vasoconstriction and vasorelaxation components. The vasoconstrictive effects of 5-HT have been well studied while the mechanism(s) of how 5-HT causes relaxation of coronary arteries has been less investigated. In isolated rat hearts, 5-HT-induced coronary flow increases are partially resistant to the nitric oxide synthase inhibitor Nω-Nitro-L-arginine methyl ester (L-NAME) and are blocked by 5-HT7 receptor antagonists. In the present study, we investigated the role of 5-HT7 receptor in 5-HT-induced coronary flow increases in isolated rat hearts in the absence of L-NAME, and we also evaluated the involvement of endothelium-derived hyperpolarizing factor (EDHF) in 5-HT-induced coronary flow increases in L-NAME-treated hearts with the inhibitors of arachidonic acid metabolism and the blockers of Ca(2+)-activated K(+) channels. RESULTS: In isolated rat hearts, 5-HT and the 5-HT7 receptor agonist 5-carboxamidotryptamine induced coronary flow increases, and both of these effects were blocked by the selective 5-HT7 receptor antagonist SB269970; in SB269970-treated hearts, 5-HT induced coronary flow decreases, which effect was blocked by the 5-HT2A receptor blocker R96544. In L-NAME-treated hearts, 5-HT-induced coronary flow increases were blocked by the phospholipase A2 inhibitor quinacrine and the cytochrome P450 inhibitor SKF525A, but were not inhibited by the cyclooxygenase inhibitor indomethacin. As to the effects of the Ca(2+)-activated K(+) channel blockers, 5-HT-induced coronary flow increases in L-NAME-treated hearts were inhibited by TRAM-34 (intermediate-conductance Ca(2+)-activated K(+) channel blocker) and UCL1684 (small-conductance Ca(2+)-activated K(+) channel blocker), but effects of the large-conductance Ca(2+)-activated K(+) channel blockers on 5-HT-induced coronary flow increases were various: penitrem A and paxilline did not significantly affect 5-HT-induced coronary flow responses while tetraethylammonium suppressed the coronary flow increases elicited by 5-HT. CONCLUSION: In the present study, we found that 5-HT-induced coronary flow increases are mediated by the activation of 5-HT7 receptor in rat hearts in the absence of L-NAME. Metabolites of cytochrome P450s, small-conductance Ca(2+)-activated K(+) channel, and intermediate-conductance Ca(2+)-activated K(+) channel are involved in 5-HT-induced coronary flow increases in L-NAME-treated hearts, which resemble the mechanisms of EDHF-induced vasorelaxation. The role of large-conductance Ca(2+)-activated K(+) channel in 5-HT-induced coronary flow increases in L-NAME-treated hearts needs further investigation.

Pyrrolidinyl caffeamide against ischemia/reperfusion injury in cardiomyocytes through AMPK/AKT pathways.

BACKGROUND: Coronary heart disease is a leading cause of death in the world and therapy to reduce injury is still needed. The uncoupling of glycolysis and glucose oxidation induces lactate accumulation during myocardial ischemia/reperfusion (I/R) injury. Cell death occurs and finally leads to myocardial infarction. Caffeic acid, one of the major phenolic constituents in nature, acts as an antioxidant. Pyrrolidinyl caffeamide (PLCA), a new derivative of caffeic acid, was synthesized by our team. We aimed to investigate the effect of PLCA on hypoxia/reoxygenation (H/R) in neonatal rat ventricular myocytes (NRVM) and on myocardial I/R in rats. RESULTS: Cardiomyocytes were isolated and subjected to 6 h hypoxia followed by 18 h reperfusion. PLCA (0.1 to 3 µM) and metformin (30 µM) were added before hypoxia was initiated. PLCA at 1 µM and metformin at 30 µM exerted similar effects on the improvement of cell viability and the alleviation of cell apoptosis in NRVM after H/R. PLCA promoted p-AMPK, p-AKT, and GLUT4 upregulation to induce a cardioprotective effect in both cell and animal model. The accumulation of cardiac lactate was attenuated by PLCA during myocardial I/R, and infarct size was smaller in rats treated with PLCA (1 mg/kg) than in those treated with caffeic acid (1 mg/kg). CONCLUSIONS: AMPK and AKT are synergistically activated by PLCA, which lead facilities glucose utilization, thereby attenuating lactate accumulation and cell death. The cardioprotective dose of PLCA was lower than those of metformin and caffeic acid. We provide a new insight into this potential drug for the treatment of myocardial I/R injury.

Increased LDL electronegativity in chronic kidney disease disrupts calcium homeostasis resulting in cardiac dysfunction.

Chronic kidney disease (CKD), an independent risk factor for cardiovascular disease, is associated with abnormal lipoprotein metabolism. We examined whether electronegative low-density lipoprotein (LDL) is mechanistically linked to cardiac dysfunction in patients with early CKD. We compared echocardiographic parameters between patients with stage 2 CKD (n = 88) and normal controls (n = 89) and found that impaired relaxation was more common in CKD patients. Reduction in estimated glomerular filtration rate was an independent predictor of left ventricular relaxation dysfunction. We then examined cardiac function in a rat model of early CKD induced by unilateral nephrectomy (UNx) by analyzing pressure-volume loop data. The time constant of isovolumic pressure decay was longer and the maximal velocity of pressure fall was slower in UNx rats than in controls. When we investigated the mechanisms underlying relaxation dysfunction, we found that LDL from CKD patients and UNx rats was more electronegative than LDL from their respective controls and that LDL from UNx rats induced intracellular calcium overload in H9c2 cardiomyocytes in vitro. Furthermore, chronic administration of electronegative LDL, which signals through lectin-like oxidized LDL receptor-1 (LOX-1), induced relaxation dysfunction in wild-type but not LOX-1(-/-) mice. In in vitro and in vivo experiments, impaired cardiac relaxation was associated with increased calcium transient resulting from nitric oxide (NO)-dependent nitrosylation of SERCA2a due to increases in inducible NO synthase expression and endothelial NO synthase uncoupling. In conclusion, LDL becomes more electronegative in early CKD. This change disrupts SERCA2a-regulated calcium homeostasis, which may be the mechanism underlying cardiorenal syndrome.

The differential effects of a selective kappa-opioid receptor agonist, U50488, in guinea pig heart tissues.

The differential effects of a selective kappa- (κ-) opioid receptor agonist, U50488, were elucidated by monitoring the contraction of isolated guinea pig atrial and ventricular muscles. In electrically driven left atria, U50488 in nanomolar concentration range decreased the contractile force. Norbinaltorphimine (norBNI), a selective κ-receptor antagonist, and pertussis toxin (PTX) abolished the negative inotropic effect of U50488. In contrast, the inhibitory effect was not affected by the pretreatment of atropine or propranolol. Even though U50488 exerted a negative inotropic effect in the left atrium, it did not affect the contractile force of the right atrium and ventricles paced at 2 Hz. Similarly, the beating rate of the spontaneously beating right atrium was also unaffected by U50488. These results indicate that the activation of κ-opioid receptors can only produce negative inotropic effect in left atria via activation of PTX-sensitive G protein in guinea pigs. The absence of negative inotropic effects in right atria and ventricles suggests that there may be a greater distribution of functional κ-opioid receptors in guinea pig left atria than in right atria and ventricles, and the distribution of the receptors may be species-specific.

TM-1-1DP exerts protective effect against myocardial ischemia reperfusion injury via AKT-eNOS pathway.

Coronary heart disease remains a leading cause of death in the world. The demand on targeting therapy to reduce myocardial ischemia/reperfusion (I/R) injury is still urgent. The pathogenesis of I/R-induced myocardial injury is complicated. Reactive oxygen species (ROS) generation and inflammatory response activation participate in the development of I/R injury. Cell death occurs and finally leads to myocardial infarction. A newly phenolic aporphine alkaloid derivative, TM-1-1DP, was synthesized in our team. We aimed to investigate the effect of novel compound on myocardial I/R injury. Rats were subjected to 1-h coronary artery occlusion and followed by 2-h reperfusion. Adult rat cardimoycyte was isolated for the cell study, and H2O2 was added into culture medium to induce ROS stress. As compared to the sham group, TM-1-1DP-treated rats had better cardiac performance in association with less infarct size and cardiac injury markers after myocardial I/R. The protective effect is associated with the inhibition of inflammatory response, cell death-related pathway (caspase-3 and TNF-α), and the activation of AKT-eNOS pathway. The finding was further coincided with the cell study. TM-1-1DP treatment significantly alleviated ROS production and improved cell viability in cardiomyocyte after H2O2 exposure. The action of TM-1-1DP is via a nitric oxide (NO)-dependent manner, since NOS inhibitor, L-NAME, abolished the protective effect. We provide a new insight into this therapeutic potential for phenolic aporphine alkaloid in myocardial I/R.

The effect of resveratrol on protecting corneal epithelial cells from cytotoxicity caused by moxifloxacin and benzalkonium chloride.

PURPOSE: Moxifloxacin (MOX), a fourth generation fluoroquinolone (FQ), has a wide antibacterial spectrum, but may show cytotoxicity characterized by high productions of reactive oxygen species (ROS). This study investigated the protective role of a common antioxidant agent, resveratrol (trans-3,5,4'-trihydroxystilbene), against the cytotoxicity caused by MOX. METHODS: Experiments were performed with a human corneal epithelial cell line (HCECs; ATCC-CRL-11515). Another commonly used FQ, levofloxacin (LEV), and the most commonly used preservatives, benzalkonium chloride (BAC), were also used for comparison with MOX. Cell viability and morphologic changes after treatment were evaluated with trypan blue exclusion assay, propidium iodine/annexin V-FITC staining, and flow cytometry. Chemiluminescence immunoassay was used for ROS quantification. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay, wound healing assay, and intracellular detections of oxidative stress were performed to evaluate the effects of resveratrol. RESULTS: The MOX group, similar to the BAC group, showed significant cell shrinkage and death compared with the LEV group. High ROS production in HCECs of MOX group was observed both by chemiluminescence immunoassay and intracellular images. Within the observations of MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assay, live cell images, and wound healing process in vitro, the cytotoxic effects of the MOX and BAC groups were opposed by resveratrol. Human corneal epithelial cells pretreated with resveratrol demonstrated better cell viability and healing rate in the early stage. CONCLUSIONS: The protective effects of antioxidant agents indicate that MOX, similar to BAC, causes oxidative stress-related cell damage. The results also inspired us to think about a "supplementary regimen" to increase safety and decrease the adverse effect in the treatment of corneal infections.

KS370G, a caffeamide derivative, attenuates unilateral ureteral obstruction-induced renal fibrosis by the reduction of inflammation and oxidative stress in mice.

Unilateral ureteral obstruction (UUO) is an established animal model used to study renal nephropathy. Caffeic acid phenethyl ester, a natural phenolic compound, possesses antifibrotic, anti-inflammation and anti-oxidative stress effects; however, rapid decomposition by esterases substantially decreases its bioavailability. The goal of this study was to investigate the beneficial effects of KS370G, a synthetic caffeamide derivative, on UUO-induced renal injury. Following the UUO, KS370G (10mg/kg) was administered by oral gavage once a day. Renal injury was analyzed at 14 days post-operation. Our results show that KS370G significantly attenuated collagen deposition in the obstructed kidney and inhibited UUO-induced renal fibrosis markers expression, including fibronectin, type I collagen, vimentin, and α-smooth muscle actin (α-SMA). KS370G significantly lowered the expression of renal inflammatory chemokines/adhesion molecules and monocyte cells marker (MCP-1, VCAM-1, ICAM-1 and CD11b). KS370G also reduced renal malondialdehyde levels and reversed the expression of renal antioxidant enzymes (SOD and catalase) after UUO. Furthermore, KS370G significantly inhibited UUO-induced elevated plasma AngII and TGF-ß1 levels, TGF-ß1 protein expression and Smad3 phosphorylation. These findings demonstrate that KS370G reduces renal obstructive nephropathy by possibly inhibiting AngII, TGF-ß and Smad3 signaling pathways.

Activation of serotonin 5-HT7 receptor induces coronary flow increase in isolated rat heart.

Serotonin (5-Hydroxytryptamine, 5-HT) can elicit both vasoconstrictive and relaxant responses on rat coronary artery. The constrictive response has been well discussed, but the mechanism of relaxant response is less studied. In the present study, we found serotonin (0.3 and 1 µM) increased coronary flow on isolated rat hearts, and treatment of nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) 300 µM reduced but not totally blocked this coronary flow increasing effect. In L-NAME 10 µM treated heart, treatment of selective serotonin 5-HT7 receptor antagonist SB269970 0.1 µM blocked serotonin induced coronary flow increasing response, and in the presence of 1 µM SB269970, serotonin turned into reducing coronary flow. Treatment of TCW295 (8-(2,4-Dimethoxyphenyl)-6-methoxy-2-phenethyl-1,2,3,4-tetrahydroisoquinolin-7-ol hydrochloride), a novel serotonin 5-HT2A/7 receptor antagonist, inhibited both serotonin induced coronary flow increasing and decreasing effects. In conclusion, we found serotonin increases coronary flow of isolated rat heart by activating serotonin 5-HT7 receptor activation, and this effect can be, at least partially, resistant to L-NAME.