Protective effect of gap junction uncouplers given during hypoxia against reoxygenation injury in isolated rat hearts.
نویسندگان
چکیده
It has been shown that cell-to-cell chemical coupling may persist during severe myocardial hypoxia or ischemia. We aimed to analyze the effects of different, chemically unrelated gap junction uncouplers on the progression of ischemic injury in hypoxic myocardium. First, we analyzed the effects of heptanol, 18alpha-glycyrrhetinic acid, and palmitoleic acid on intracellular Ca2+ concentration during simulated hypoxia (2 mM NaCN) in isolated cardiomyocytes. Next, we analyzed their effects on developed and diastolic tension and electrical impedance in 47 isolated rat hearts submitted to 40 min of hypoxia and reoxygenation. All treatments were applied only during the hypoxic period. Cell injury was determined by lactate dehydrogenase (LDH) release. Heptanol, but not 18alpha-glycyrrhetinic acid nor palmitoleic acid, attenuated the increase in cytosolic Ca2+ concentration induced by simulated ischemia in cardiomyocytes and delayed rigor development (rigor onset at 7.31 +/- 0.71 min in controls vs. 14.76 +/- 1.44 in heptanol-treated hearts, P < 0.001) and the onset of the marked changes in electrical impedance (tissue resistivity: 4.02 +/- 0.29 vs. 7.75 +/- 1.84 min, P = 0.016) in hypoxic rat hearts. LDH release from hypoxic hearts was minimal and was not significantly modified by drugs. However, all gap junction uncouplers, given during hypoxia, attenuated LDH release during subsequent reoxygenation. Dose-response analysis showed that increasing heptanol concentration beyond the level associated with maximal effects on cell coupling resulted in further protection against hypoxic injury. In conclusion, gap junction uncoupling during hypoxia has a protective effect on cell death occurring upon subsequent reoxygenation, and heptanol has, in addition, a marked protective effect independent of its uncoupling actions.
منابع مشابه
Cardioprotective effects of PKG activation by soluble GC activator, BAY 60-2770, in ischemia-reperfusion-injured rat hearts
Soluble guanylate cyclase (sGC) has been suggested as a therapeutic target for cardiac ischemia-reperfusion (IR) injury. Until now, the molecular mechanism of BAY 60-2770, a sGC activator, in cardiac IR injury has not been assessed. To identify the cardioprotective effects of BAY 60-2770 in IR-injured rat hearts, IR injury was established by occlusion of LAD for 40 min and reperfusion for 7 day...
متن کاملChanges in cyclic nucleotide levels and contractile force in the isolated hypoxic rat heart during perfusion with glucagon.
Isolated rat hearts were perfused with hormonal concentrations of glucagon during a hypoxic perfusion to determine whether it would enhance recovery after reoxygenation. Rat hearts were divided into two groups: (1) those perfused with glucose-free Tyrode's solution and (2) those perfused with Tyrode's solution containing glucose. During 3 minutes of exposure to hypoxia both untreated hearts and...
متن کاملProtective effect of bioactive compounds from Lonicera japonica Thunb. against H2O2-induced cytotoxicity using neonatal rat cardiomyocytes
Objective(s):Pharmacological studies showed that the extracts of Jin Yin Hua and its active constituents have lipid lowering, antipyretic, hepatoprotective, cytoprotective, antimicrobial, antibiotic, antioxidative, antiviral, and anti-inflammatory effects. The purpose of the present study was to investigate the protective effects of caffeoylquinic acids (CQAs) from Jin Yin Hua against hydrogen ...
متن کاملNo evidence for protective erythropoietin alpha signalling in rat hepatocytes
BACKGROUND Recombinant human erythropoietin alpha (rHu-EPO) has been reported to protect the liver of rats and mice from ischemia-reperfusion injury. However, direct protective effects of rHu-EPO on hepatocytes and the responsible signalling pathways have not yet been described. The aim of the present work was to study the protective effect of rHu-EPO on warm hypoxia-reoxygenation and cold-indu...
متن کاملHypoxia-reoxygenation induced necroptosis in cultured rat renal tubular epithelial cell line
Objective(s): The aim of this study is to explore the potential role of hypoxia/reoxygenation in necroptosis in cultured rat renal tubular epithelial cell line NRK-52E, and further to investigate its possible mechanisms.Materials and Methods: Cells were cultured under different hypoxia-reoxygenation conditions in vitro. MTT assay was used to measure the cell proliferation...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- American journal of physiology. Heart and circulatory physiology
دوره 290 2 شماره
صفحات -
تاریخ انتشار 2006