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.

Assessment of Myofilament Ca2+ Sensitivity Underlying Cardiac Excitation-contraction Coupling.

Heart failure and cardiac arrhythmias are the leading causes of mortality and morbidity worldwide. However, the mechanism of pathogenesis and myocardial malfunction in the diseased heart remains to be fully clarified. Recent compelling evidence demonstrates that changes in the myofilament Ca(2+) sensitivity affect intracellular Ca(2+) homeostasis and ion channel activities in cardiac myocytes, the essential mechanisms responsible for the cardiac action potential and contraction in healthy and diseased hearts. Indeed, activities of ion channels and transporters underlying cardiac action potentials (e.g., Na(+), Ca(2+) and K(+) channels and the Na(+)-Ca(2+) exchanger) and intracellular Ca(2+) handling proteins (e.g., ryanodine receptors and Ca(2+)-ATPase in sarcoplasmic reticulum (SERCA2a) or phospholamban and its phosphorylation) are conventionally measured to evaluate the fundamental mechanisms of cardiac excitation-contraction (E-C) coupling. Both electrical activities in the membrane and intracellular Ca(2+) changes are the trigger signals of E-C coupling, whereas myofilament is the functional unit of contraction and relaxation, and myofilament Ca(2+) sensitivity is imperative in the implementation of myofibril performance. Nevertheless, few studies incorporate myofilament Ca(2+) sensitivity into the functional analysis of the myocardium unless it is the focus of the study. Here, we describe a protocol that measures sarcomere shortening/re-lengthening and the intracellular Ca(2+) level using Fura-2 AM (ratiometric detection) and evaluate the changes of myofilament Ca(2+) sensitivity in cardiac myocytes from rat hearts. The main aim is to emphasize that myofilament Ca(2+) sensitivity should be taken into consideration in E-C coupling for mechanistic analysis. Comprehensive investigation of ion channels, ion transporters, intracellular Ca(2+) handling, and myofilament Ca(2+) sensitivity that underlie myocyte contractility in healthy and diseased hearts will provide valuable information for designing more effective strategies of translational and therapeutic value.

UFT and its metabolite gamma-butyrolactone (GBL) inhibit angiogenesis induced by vascular endothelial growth factor in advanced cervical carcinoma.

OBJECTIVE: The aim of this study was to evaluate the potential role of UFT and its metabolite gamma-butyrolactone (GBL) for inhibition of angiogenesis induced by vascular endothelial growth factor (VEGF) in advanced cervical carcinoma by the determination of serum GBL and VEGF, and by immunohistochemical staining to assess VEGF protein expression, before and after UFT therapy. METHODS: The subjects were 35 patients with an advanced cervical carcinoma and five healthy volunteers between 2002 and 2003 at Hiroshima University Hospital, under informed consent. The patients received two courses of oral fluoropyrimidine (UFT) therapy at a dose of 600 mg/day for 5 and 2 days off treatment. Serum GBL and VEGF was measured before and after UFT therapy by the gas chromatography mass spectrometry and ELISA-kit in 22 patients and five healthy volunteers, respectively. Immunohistochemical detection of VEGF protein was done in 35 cervical cancers. Results The mean serum GBL level before and after UFT therapy was 21.9 +/- 2.3 and 79.3 +/- 6.2 ng/ml, respectively, and it was significantly increased after UFT administration (P < 0.0001). The mean serum VEGF level before and after UFT therapy was 95.3 +/- 28.1 and 67.5 +/- 11.2 pg/ml, respectively, and it was decreased by UFT administration. In 20 out of 33 (66.6%) patients who were detected with VEGF protein, VEGF protein expression was decreased by UFT therapy. The Delta GBL value (GBL after UFT--GBL before UFT therapy) showed a significant inverse correlation with Delta VEGF value (VEGF after therapy--VEGF before therapy) (r2 = 0.940). CONCLUSIONS: Our findings suggest that UFT and its metabolite GBL inhibit angiogenesis induced by VEGF to have an antitumor effect on cervical cancer.