Potential mechanisms for the enhancement of HERG K+ channel function by phospholipid metabolites.

1. Phospholipid metabolites lysophospholipids cause extracellular K(+) accumulation and action potential shortening with increased risk of arrhythmias during myocardial ischemia. Here we studied effects of several lysophospholipids with different lengths of hydrocarbon chains and charged headgroups on HERG K(+) currents (I(HERG)) expressed in HEK293 cells and the potential mechanisms using whole-cell patch-clamp techniques.

Progressive apoptotic cell death triggered by transient oxidative insult in H9c2 rat ventricular cells: a novel pattern of apoptosis and the mechanisms.

Many pathophysiological processes are associated with oxidative stress and progressive cell death. Oxidative stress is an apoptotic inducer that is known to cause rapid cell death. Here we show that a brief oxidative insult (5-min exposure to 400 microM H(2)O(2)), although it did not kill H9c2 rat ventricular cells during the exposure, triggered an intracellular death cascade leading to delayed time-dependent cell death starting from 1 h after the insult had been withdrawn, and this post-H(2)O(2) cell death cumulated gradually, reaching a maximum level 8 h after H(2)O(2) withdrawal.

Opposite cell density-dependence between spontaneous and oxidative stress-induced apoptosis in mouse fibroblast L-cells.

Background/aims: Spontaneous apoptosis in culture is cell density-dependent. Yet, little is known about the density-dependence of apoptosis induced by oxidative stress and the underlying signaling mechanisms.

Methods: We compared apoptosis occurring spontaneously and induced by H2O2 in mouse fibroblast L-cells seeded at three different densities, using ELISA and TUNEL to measure DNA fragmentation, Western blot and pharmacological probes to evaluate the roles of signaling molecules.

[The viral resistance of transgenic tobacco plants containing untranslatable PVYN coat protein gene].

In previous study, we have proved that the resistance of the transgenic tobacco plants containing untranslatable PVYN CP gene was mediated by PVYN CP transgene RNAs, and the resistance mechanism was similar to PTGS. In this paper, T0 progeny transgenic lines with different resistant levels were selected to further study the transgene inheritance and resistant stability of transgenic plants. Results showed that T0 progeny susceptible lines, which contained 1-2 transgene copies, displayed a 3:1 segregation ratio in T1 progeny lines; T0 progeny middle resistant lines, which contained 3-4 transgene copies, revealed a 15:1 segergation ratio in T1 progeny lines; T0 progeny highly resistant lines, which contained 5-7 transgene copies, followed 15:1 or 63:1 segregation pattern in T1 progeny lines.

CB(1) cannabinoid receptor antagonism promotes remodeling and cannabinoid treatment prevents endothelial dysfunction and hypotension in rats with myocardial infarction.

1. To study the long-term effects of altered cannabinoid receptor activity on myocardial and vascular function, Wistar rats were treated with the selective CB(1) antagonist AM-251 (0.5 mg kg(-1) d(-1)), the potent synthetic cannabinoid HU-210 (50 micro g kg(-1) d(-1)) or vehicle for 12 weeks after coronary artery ligation or sham operation.

Impairment of human ether-à-go-go-related gene (HERG) K+ channel function by hypoglycemia and hyperglycemia. Similar phenotypes but different mechanisms.

Hyperglycemia and hypoglycemia both can cause prolongation of the Q-T interval and ventricular arrhythmias. Here we studied modulation of human ether-à-go-go-related gene (HERG) K(+) channel, the major molecular component of delayed rectifier K(+) current responsible for cardiac repolarization, by glucose in HEK293 cells using whole-cell patch clamp techniques. We found that both hyperglycemia (extracellular glucose concentration [Glu](o) = 10 or 20 mm) and hypoglycemia ([Glu](o) = 2.

Normal function of HERG K+ channels expressed in HEK293 cells requires basal protein kinase B activity.

The potential role of protein kinase B (PKB), a serine/threonine protein kinase, in regulating HERG (human ether-a-go-go related gene) K(+) channel function was investigated. Wortmannin (a phosphoinositide 3-kinase (PI3K) inhibitor) caused approximately 30% reduction of HERG current (I(HERG)) stably expressed in HEK293 cells. Transient transfection with the constitutively active PI3K in HERG-expressing HEK293 cells slightly increased ( approximately 7%) I(HERG) while a dominant negative PI3K significantly reduced I(HERG) ( approximately 25%) relative to results in vehicle-transfected cells.

Ultrarapid delayed rectifier K(+) current in H9c2 rat ventricular cell line: biophysical property and molecular identity.

Ultrarapid delayed rectifier K(+) currents (I(Kur)s) contribute importantly to cardiac repolarization. However, understanding of I(Kur)s has been hampered by the difficulty of dissecting them from overlapping currents in primary cells. We found with whole-cell patch-clamp recordings that H9c2 cells, a rat ventricular cell line, under 50% confluence (single myoblasts) express exclusively I(Kur)-like current which activates rapidly upon depolarization and partially inactivates during 150-ms pulses.

HERG K+ channel, a regulator of tumor cell apoptosis and proliferation.

The human ether-a-go-go related gene (HERG) encodes K+ channel identified as a molecular target for mutations underlying some forms of the long Q-T syndrome, a lethal cardiac arrhythmia. Recent studies revealed that HERG is abundantly expressed in a variety of tumor cells. Yet, the role of HERG in tumor cells had remained unclear.

Angiotensin II subtype 1 (AT1) receptors contribute to ischemic contracture and regulate chemomechanical energy transduction in isolated transgenic rat (alphaMHC-hAT1)594-17 hearts.

Background: The role of AT1 receptors in myocardial ischemia/reperfusion injury is unclear. We, therefore, investigated the effects of the AT1 receptor antagonist irbesartan (Irb) in isolated hearts of selective myocardial AT1 overexpressing transgenic [transgenic(alphaMHC-hAT1)594-17] and Sprague-Dawley rats (SD) subjected to ischemia/reperfusion injury.

Methods And Results: Hearts of 4-week-old male SD or transgenic rats were isolated and perfused with Krebs-Henseleit buffer with or without 10 microM Irb in Langendorff mode.

[Study on natural infection of Plasmodium vivax in Anopheles sinensis in Korea].

On epidemiological grounds, Anopheles sinensis has been suspected for many years to be the malaria vector in Korea. Of 7,517 dissections of A. sinensis, one specimen was found for the first time in Korea naturally infected with sporozoites in August 1962.