Effects of liraglutide on ANP secretion and cardiac dynamics.

To observe the effects of liraglutide (analog of glucagon-like peptide 1 (GLP-1)) on atrial natriuretic peptide (ANP) secretion and atrial dynamics, an ex vivo isolated rat atrial perfusion model was used to determine atrial ANP secretion and pulse pressure. DPP-4-/- mice were also established in vivo. ANP levels were determined by radioimmunoassay; GLP-1 content was determined by Elisa. The expression levels of GLP-1 receptor (GLP-1R), PI3K/AKT/mTOR, piezo 1, and cathepsin K were analyzed by Western blot. In the clinical study, patients with acute coronary syndrome (ACS) had low levels of plasma GLP-1 but relatively high levels of plasma ANP. In ex vivo (3.2 nmol/L) and in vivo (30 µg/kg) models, liraglutide significantly decreased ANP levels and atrial pulse pressure. Exendin9-39 alone (GLP-1R antagonist) reversibly significantly increased ANP secretion, and the reduction effect of liraglutide on the secretion of ANP was significantly alleviated by Exendin9-39. Exendin9-39 demonstrated slightly decreased atrial pulse pressure; however, combined liraglutide and Exendin9-39 significantly decreased atrial pulse pressure. Ly294002 (PI3K/AKT inhibitor) inhibited the increase of ANP secretion by liraglutide for a short time, while Ly294002 didn't counteract the decrease in pulse pressure by liraglutide in atrial dynamics studies. Liraglutide increased the expression of GLP-1R and PI3K/AKT/mTOR in isolated rat atria and the hearts of mice in vivo, whereas Exendin9-39 reversibly reduced the expression of GLP-1R and PI3K/AKT/mTOR. Piezo 1 was significantly decreased in wild type and DPP-4-/- mouse heart or isolated rat atria after being treated with liraglutide. Cathepsin K expression was only decreased in in vivo model hearts. Liraglutide can inhibit ANP secretion while decreasing atrial pulse pressure mediated by GLP-1R. Liraglutide probably plays a role in the reduction of ANP secretion via the PI3K/AKT/mTOR signaling pathway. Piezo 1 and cathepsin K may be involved in the liraglutide mechanism of reduction.

Abnormal hubs in global network as neuroimaging biomarker in right temporal lobe epilepsy at rest.

While abnormal neuroimaging features have been reported in patients suffering from right temporal lobe epilepsy (rTLE), the value of altered degree centrality (DC) as a diagnostic biomarker for rTLE has yet to be established. As such, the present study was designed to examine DC abnormalities in rTLE patients in order to gauge the diagnostic utility of these neuroimaging features. In total, 68 patients with rTLE and 73 healthy controls (HCs) participated in this study. Imaging data were analyzed using DC and receiver operating characteristic (ROC) methods. Ultimately, rTLE patients were found to exhibit reduced right caudate DC and increased left middle temporal gyrus, superior parietal gyrus, superior frontal gyrus, right precuneus, frontal gyrus Inferior gyrus, middle-superior frontal gyrus, and inferior parietal gyrus DC relative to HC. ROC analyses indicated that DC values in the right caudate nucleus could be used to differentiate between rTLE patients and HCs with a high degree of sensitivity and specificity. Together, these results thus suggest that rTLE is associated with abnormal DC values in the right caudate nucleus, underscoring the relevance of further studies of the underlying pathophysiology of this debilitating condition.

CD44 enhances adriamycin resistance in chronic myelogenous leukaemia cells K562.

INTRODUCTION: To investigate CD44 effects on the adriamycin-resistant in chronic myelogenous leukaemia cells K562, we explored the role of CD44 in the K562 cells migration and apoptosis. METHODS: GeneChip® screening is used for elucidating various chemoresistance-related gene expression in the adriamycin-resistant leukaemia cells K562/ADR. We constructed K562/CD44 cells by transfection of an EGFP-SV40-CD44 plasmid, and adriamycin-resistant ability was confirmed by detecting migration and apoptosis-related proteins and mRNA expression using Western blotting and Real-time PCR respectively. RESULTS: K562/CD44 cells were generated by the transfection of an EGFP-SV40-CD44 plasmid with high CD44 expression. mRNA expression levels of CD44 and P-glycoprotein (P-gp), along with the proliferation rate, were increased, while the apoptosis rate of K562/CD44 cells was decreased. Migration-associated proteins such as MMP-2 and MMP-9 were upregulated, whereas apoptosis-related protein Bax was downregulated and Bcl-2 protein was not significantly altered in the K562/CD44 cells. CONCLUSIONS: CD44 might be involved in adriamycin resistance via regulation of P-gp, MMP-2, MMP-9, and Bcl-2/Bax.

Ginsenoside Re prevents angiotensin II-induced gap-junction remodeling by activation of PPARγ in isolated beating rat atria.

AIMS: Ginsenoside Re (G-Re), a major ginsenoside in ginseng, has many beneficial pharmacological effects on negative cardiac contractility, electromechanical alternans, antiarrhythmia, angiogenic regeneration and cardiac electrophysiological function. However, effects of G-Re on gap-junction remodeling are unclear. Therefore, this study aimed to investigate the effect of G-Re on angiotensin II (Ang II)-induced downregulation of connexin-40 (CX40) and -43 (CX43) in beating rat left atria. MAIN METHODS: In this study, the isolated perfused beating rat atrial model was used and atrial gap-junction remodeling was induced by Ang II. In vivo hemodynamic experiments were analyzed with a biological recorder. Changes in protein expression were analyzed by western blot. KEY FINDINGS: G-Re attenuated Ang II-induced abnormal changes in heart rate, MAP, LVESP, LVEDP, +dp/dt max, -dp/dt min, P wave amplitude, P-R interval and P wave length. This indicated a dose-dependent preventive role against Ang II-induced hyper hemodynamics in rats. Atrial activities of p38 mitogen-activated protein kinase (MAPK), nuclear factor kappa-B (NF-κB) and activator protein 1 (AP-1) were significantly increased by Ang II, as was expression of atrial collagen I and matrix metalloproteinase 2 (MMP2). Atrial CX40 and CX43 expression was downregulated by Ang II. These Ang II-induced atrial effects were blocked by G-Re, as well as rosiglitazone, an agonist of peroxisome proliferator-activated receptor γ (PPARγ), in a dose-dependent manner. However, this inhibition was abolished by the PPARγ inhibitor GW9662. SIGNIFICANCE: G-Re may suppress Ang II-induced downregulation of CX40 and CX43, by activating PPARγ signaling, in isolated perfused beating rat atria.

Mechanically Induced Ectopy via Stretch-Activated Cation-Nonselective Channels Is Caused by Local Tissue Deformation and Results in Ventricular Fibrillation if Triggered on the Repolarization Wave Edge (Commotio Cordis).

BACKGROUND: External chest impacts (commotio cordis) can cause mechanically induced premature ventricular excitation (PVEM) and, rarely, ventricular fibrillation (VF). Because block of stretch-sensitive ATP-inactivated potassium channels curtailed VF occurrence in a porcine model of commotio cordis, VF has been suggested to arise from abnormal repolarization caused by stretch activation of potassium channels. Alternatively, VF could result from abnormal excitation by PVEM, overlapping with normal repolarization-related electric heterogeneity. Here, we investigate mechanisms and determinants of PVEM induction and its potential role in commotio cordis-induced VF. METHODS AND RESULTS: Subcontusional mechanical stimuli were applied to isolated rabbit hearts during optical voltage mapping, combined with pharmacological block of ATP-inactivated potassium or stretch-activated cation-nonselective channels. We demonstrate that local mechanical stimulation reliably triggers PVEM at the contact site, with inducibility predicted by local tissue indentation. PVEM induction is diminished by pharmacological block of stretch-activated cation-nonselective channels. In hearts where electrocardiogram T waves involve a well-defined repolarization edge traversing the epicardium, PVEM can reliably provoke VF if, and only if, the mechanical stimulation site overlaps the repolarization wave edge. In contrast, application of short-lived intraventricular pressure surges neither triggers PVEM nor changes repolarization. ATP-inactivated potassium channel block has no effect on PVEM inducibility per se, but shifts it to later time points by delaying repolarization and prolonging refractoriness. CONCLUSIONS: Local mechanical tissue deformation determines PVEM induction via stretch-activation of cation-nonselective channels, with VF induction requiring PVEM overlap with the trailing edge of a normal repolarization wave. This defines a narrow, subject-specific vulnerable window for commotio cordis-induced VF that exists both in time and in space.

Vascular responses to compound 48/80 in rat mesenteric vascular beds.

A further investigation was performed on the vascular effect of endogenous histamine using the histamine releaser, compound 48/80, in rat mesenteric vascular beds with active tone. In preparations with intact endothelium, low concentrations of compound 48/80 (1.53 × 10(-5) - 3 × 1.53 × 10(-5) mg/mL) perfusion for 1 min only induced a small vasodilation. High concentrations of compound 48/80 (1.53 × 10(-4) - 3 × 1.53 × 10(-2) mg/mL) induced a biphasic vascular responses, an initial vasoconstriction followed a subsequent long-lasting vasodilation. The vasodilation induced by low concentrations of compound 48/80 and the vasoconstriction induced by high concentration of compound 48/80 was inhibited by olopatadine. However, cimetidine did not affect the responses induced by compound 48/80. Endothelium removal enlarged the compound 48/80-induced phase-2 vasoconstriction, while it attenuated the phase-3 vasodilation. Additionally, indomethacin and seratrodast significantly inhibited vasoconstriction but it did not affect the long-lasting vasodilation induced by high concentrations of compound 48/80. Ruthenium red inhibited the vasodilation induced by low concentrations and high concentrations of compound 48/80. These results suggest that the vasoconstriction induce by high concentrations of compound 48/80 is mediated by endogenous histamine released from mast cells. It is also suggested that thromboxane A2 released from mast cells is related to the vasoconstriction.

Involvement of perivascular nerves and transient receptor potential vanilloid 1 (TRPV1) in vascular responses to histamine in rat mesenteric resistance arteries.

A previous report showed that histamine in denuded mesenteric vascular beds produced a triphasic response; an initial small histamine H(2) receptor-mediated vasodilation, a transient histamine H(1) receptor-mediated vasoconstriction, and finally a long-lasting vasodilation. We further investigated the vascular effect of histamine in mesenteric preparations without an endothelium to clarify the possible involvement of perivascular nerves. Male Wistar rat mesenteric vascular beds without an endothelium were perfused with Krebs solution containing methoxamine to produce active tone and lafutidine to block histamine H(2) receptor-mediated vasodilation. Histamine (1-100µM) was perfused for 1min and perfusion pressure was measured with a pressure transducer. Histamine caused a biphasic vascular response; initial vasoconstriction followed vasodilation. Tetrodotoxin (a neurotoxin, 1µM) and procaine (a local anesthetic, 100µM) significantly inhibited the vasoconstriction and vasodilation. Ruthenium red (a transient receptor potential vanilloid 1 (TRPV1) antagonist, 1µM) also significantly inhibited both phases of the response. Pretreatment with capsaicin (a depletor of calcitonin gene-related peptide (CGRP)-containing nerves, 5µM) significantly inhibited the vasodilation without affecting the initial vasoconstriction. Both indomethacin (a cyclooxygenase inhibitor, 0.5µM) and seratrodast (a thromboxane A(2) receptor antagonist, 0.1µM) abolished the histamine-induced vasoconstriction and subsequent vasodilation. These results suggest that histamine-induced vasoconstriction and long-lasting vasodilation are mediated by activation of TRPV1 on capsaicin-sensitive and capsaicin-insensitive nerves. They also suggest that perivascular nerves and prostanoids, probably thromboxane A(2), are responsible for the vascular response to histamine.

Role of sarcolemmal BK(Ca) channels in stretch-induced extrasystoles in isolated chick hearts.

BACKGROUND: It remains unclear whether sarcolemmal BK(Ca) channels in post-hatch chick ventricular myocytes contribute to stretch-induced extrasystoles (SIE), and whether they are stretch-activated BK(Ca) (SAK(Ca)) channels or a non-stretch-sensitive BK(Ca) variant. METHODS AND RESULTS: To determine the role of sarcolemmal BK(Ca) channels in SIE and their stretch sensitivity, an isolated 2-week-old Langendorff-perfused chick heart and mathematical simulation were used. The ventricular wall was rapidly stretched by application of a volume change pulse. As the speed of the stretch increased, the probability of SIE also significantly increased, significantly shortening the delay between SIE and the initiation of the stretch. Application of 100 nmol/L of Grammostola spatulata mechanotoxin 4, a cation-selective stretch-activated channel (SAC) blocker, significantly decreased the probability of SIE. The application of Iberiotoxin, however, a BK(Ca) channel blocker, significantly increased the probability of SIE, suggesting that a K(+) efflux via a sarcolemmal BK(Ca) channel reduces SIE by balancing out stretch-induced cation influx via SACs. The simulation using a cardiomyocyte model combined with a new stretch sensitivity model that considers viscoelastic intracellular force transmission showed that stretch sensitivity in BK(Ca) channels is required to reproduce the present wet experimental results. CONCLUSIONS: Sarcolemmal BK(Ca) channels in post-hatch chick ventricular myocytes are SAK(Ca) channels, and they have a suppressive effect on SIE.

Effects of axial stretch on sarcolemmal BKCa channels in post-hatch chick ventricular myocytes.

We have previously reported the electrophysiological properties of sarcolemmal stretch-activated BK(Ca) (SAKCA) channels cloned from cultured chick embryonic ventricular myocytes. However, the role of BK(Ca) channels in the electrophysiology of the more mature heart is not clear. We have investigated the effects on the BK(Ca) current of axial stretch in post-hatch ventricular myocytes. Whole-cell currents of ventricular myocytes isolated from 2-week-old chicks were recorded using the patch-clamp technique, while the cells were either held at resting length or stretched to cause a 10% increase in sarcomere length using a pair of carbon fibres attached to opposite ends of the cell. Stretch did not affect whole-cell currents immediately after the stretch was applied. However, sustained stretch for 3 min significantly increased outward currents. This stretch-induced change was reversed by applying 10 nm iberiotoxin, a specific BK(Ca) channel blocker, or a Na(+)-Ca(2+)-free environment. These results were reproduced in a computer simulation study. The present study is the first report about the sarcolemmal BK(Ca) current from post-hatch ventricular myocytes. The present results suggest that axial stretch activates BK(Ca) channels via a stretch-induced increase in the cytosolic Na(+) concentration followed by an increased Ca(2+) influx.

Expression of tumor-associated differentially expressed Gene-14 (TADG-14/KLK8) and its protein hK8 in uterine endometria and endometrial carcinomas.

To clarify the biological behavior of TADG-14/KLK8, we investigated TADG-14/KLK8 mRNA by semiquantitative RT-PCR and hK8 expression by immunohistochemistry using 37 normal endometria and 44 endometrial carcinoma tissues. TADG-14/KLK8 mRNA expression levels were significantly higher in proliferative compared to secretory phase endometria (p = 0.0143). Levels of TADG-14/KLK8 mRNA expression correlated with hK8 protein levels. hK8 was detected in 73.3% (11/15) of endometria with a significantly higher detection rate in the proliferative compared to secretory and atrophic phase endometria (p = 0.0002). High expression of hK8 was found in 61.4% of endometrial carcinomas compared to 35.1% of endometrial tissue samples (p = 0.0187). hK8 expression was significantly higher in stage I (p = 0.0433, 0.0038) and grade 1/2 (G1/2) of the tumors (p = 0.0195, 0.0044). We suggest that expression of TADG-14/KLK8may be regulated by sex steroid hormones in endometria. Our results indicate that elevated TADG-14/KLK8 expression is an early event in endometrial carcinogenesis, and may potentially serve as a useful early biomarker for the detection of endometrial carcinomas in menopausal women.

Histamine-induced vasodilation and vasoconstriction in the mesenteric resistance artery of the rat.

The present study was designed to examine the vascular response to histamine in rat perfused mesenteric vascular beds with active tone. In preparations with intact endothelium, perfusion of histamine (1 nM-100 microM) produced a concentration-dependent vasodilation. Histamine-induced vasodilation was attenuated by L-NAME (nitric oxide (NO) synthase inhibitor, 100 microM) and olopatadine (histamine H(1) receptor antagonist, 1 microM) but not by lafutidine (histamine H(2) receptor antagonist, 1 microM). Cold-storage denervation (4 degrees C for 72 h) of the preparation with intact endothelium attenuated the histamine-induced vasodilation. In preparations without endothelium, histamine at low concentrations (1-100 nM) produced only a small and rapid vasodilation, whereas histamine at concentrations higher than 1 muM produced triphasic vascular responses: initial sharp vasodilation followed by transient vasoconstriction and subsequent gradual vasodilation. Lafutidine abolished only the histamine-induced initial vasodilation. Olopatadine abolished the histamine-induced second vasoconstriction and third vasodilation. Cold-storage denervation of the denuded preparation abolished the histamine-induced second vasoconstriction and third vasodilation. These findings suggest that histamine induced endothelium-dependent vasodilation via endothelium histamine H(1) receptors and endothelium-independent vasodilation via smooth muscle histamine H(2) receptors. It is also suggested that the histamine-induced endothelium-independent vasoconstriction and vasodilation are mediated by histamine H(1) receptors and perivascular nerves.