TREK-1, TREK-2 and TRAAK are members of the two-pore domain K + (K 2P ) channel family and are activated by membrane stretch and free fatty acids. TREK-1 has been shown to be sensitive to temperature in expression systems. We studied the temperature-sensitivity of TREK-2 and TRAAK in COS-7 cells and in neuronal cells. In transfected COS-7 cells, TREK-2 and TRAAK whole-cell currents increased ∼20-fold as the bath temperature was raised from 24• C to 42• C. Similarly, in cell-attached patches of COS-7 cells, channel activity was very low, but increased progressively as the bath temperature was raised from 24• C to 42 • C. The thresholds for activation of TREK-2 and TRAAK were ∼25• C and ∼31 • C, respectively. Other K 2P channels such as TASK-3 and TRESK-2 were not significantly affected by an increase in temperature from 24• C to 37 • C. When the C-terminus of TREK-2 was replaced with that of TASK-3, its sensitivity to free fatty acids and protons was abolished, but the mutant could still be activated by heat. At 37• C, TREK-1, TREK-2 and TRAAK were sensitive to arachidonic acid, pH and membrane stretch in both cell-attached and inside-out patches. In cerebellar granule and dorsal root ganglion neurones, TREK-1, TREK-2 and TRAAK were generally inactive in the cell-attached state at 24• C, but became very active at 37• C. In cell-attached patches of ventricular myocytes, TREK-1 was also normally closed at 24• C, but was active at 37 • C. These results show that TREK-2 and TRAAK are also temperature-sensitive channels, are active at physiological body temperature, and therefore would contribute to the background K + conductance and regulate cell excitability in response to various physical and chemical stimuli.

Abstract. Various methods have been used to remove reactive oxygen species (ROS) generated from in vitro culture (IVC) conditions that can cause cell injury or death, including the application of low oxygen (O2) tension and the addition of antioxidants. The beneficial effects of antioxidants and O2 tension on IVC of porcine embryos, however, are controversial among researchers. In this study, we sought to determine the effects and optimal concentrations of antioxidants for the development of porcine embryos in an IVC system. Specifically, we examined the synergistic effects of antioxidants on development to the blastocyst stage in a culture system supplemented with L-cysteine during IVM. Of the antioxidants tested (melatonin, glutathione (GSH), β-mercaptoethanol (β-ME), N-acetylcysteine (NAC) and dithiothreitol (DTT)), addition of GSH (1 mM) or β-ME (25 μM) significantly increased development to the blastocyst stage compared with the controls without antioxidant treatment (22.2 ± 4.2% for 1 mM GSH, 25.9 ± 2.2% for 25 μM β-ME and 12-13% for the control, P<0.05). In addition, the mean cell number per blastocyst was increased by approximately 1.7-fold in the presence of GSH or β -ME. These GSH-and β-ME-induced increases in development to the blastocyst stage and total cell number, however, were not mimicked by melatonin, NAC or DTT, all of which are ROS scavengers. The combination of GSH or β-ME with L-cysteine significantly reduced high O2 tension-induced ROS production (P<0.05). These results suggest that a combination of 1 mM GSH or 25 μM β-ME with 1 mM L-cysteine could be used for production of high quality porcine blastocysts in IVC systems. Key words: Antioxidant system, Embryo, Oxidative stress, Pig (J. Reprod. Dev. 56: [575][576][577][578][579][580][581][582] 2010) he academic and industrial value of porcine embryonic technology is very high, as this technology allows for production of transgenic porcine embryos with disease-resistance genes, for xenogenic organ transplantation and for preservation of superior genotypes that are at risk of extinction. Obtaining many high-quality embryos, however, is a prerequisite for improvement of embryo technology. A large number of immature oocytes can be collected from the ovaries of slaughtered pigs, and these oocytes can then be matured, fertilized and cultured in vitro. At present, the quality of in vitro produced (IVP) porcine embryos is considerably lower than that of in vivo-derived embryos, although many investigators have attempted to improve in vitro culture systems to help produce higher quality porcine embryos.Earlier studies have shown that in vitro cultured (IVC) embryos cannot develop normally, as the oxygen (O2) tension in vitro is higher than that in the oviduct. This high O2 tension induces excessive production of reactive oxygen species (ROS), which leads to oxidative stress and impedes oocyte maturation and embryonic development [1,2]. To remove the ROS generated from IVC conditions, various methods have been used such as the application of low O2...

), a member of the two-pore domain K + (K 2P ) channel family, provides the background K + conductance in many cell types, and is a target of neurotransmitters that act on receptors coupled to Gs and Gq. We report here that TREK-2 exhibits small (TREK-2S) and large ( Phenotypes resembling TREK-2S and TREK-2L were also observed in cerebellar granule neurons that express TREK-2 mRNA. These results show that TREK-2 exhibits two primary modes of gating that give rise to two channel phenotypes under dephosphorylated conditions, and that its phosphorylation shifts the gating mode to include intermediate conducting levels. This represents a novel mechanism by which receptor agonists modulate the function of a K + channel to alter cell excitability.

No abstract

BackgroundAge and breed are considered the greatest risk factors for disease prevalence and mortality in companion dogs. Understanding the prevalence of diseases, in relation to age and breed, would support appropriate guidance for future health care strategies and provide useful information for the early diagnosis of diseases. The purpose of this study was to investigate the major medical causes for dogs visiting primary-care veterinary clinics in the Republic of Korea, stratified by age and breed.MethodsA total of 15,531 medical records of canine patients were analyzed from 11 veterinary clinics who shared data from January 1, 2016 to December 31, 2016. An electronic medical record (EMR) system was used for data collection, which included the animal identification number, age, breed, gender, neuter status, clinical information, and diagnosis. EMR data were classified using the International Classification of Disease system from the World Health Organization; presenting signs or diagnoses were identified according to breed and life stage.ResultsWithin the age groups, preventive medicine (16.7% confidence intervals (CI) [15.9–17.5]) was the most common cause for clinic visits for the <1 year and 1–3 year groups. Additionally, neutering surgery (6.6% CI [6.0–7.1]) and patella luxation (1.4% CI [1.8–2.7]) were frequently performed in these age groups. In the 4–6 year group, otitis externa (8.8% CI [7.8–10.0]) and dermatitis or eczema (8.5% CI [7.5–9.6]) were common medical problems. In older dogs (>10 year), the prevalences of heart disease, kidney disease, Cushing’s disease, and mammary tumors were higher than in the other age groups. Small and toy breed dogs comprised 67.7% of all dogs in this analysis. For all breeds, otitis externa, dermatitis or eczema, vomiting, and diarrhea were common medical problems.DiscussionThis study identified the most common medical disorders and differences in prevalences of diseases, according to age and breeds. The information from EMRs for dogs visiting primary-care veterinary clinics can provide background knowledge that is required to enable a better understanding of disease patterns and occurrence by age and breeds. The information from this study could enable the creation of strategies for preventing diseases and enable the identification of health problems for more effective disease management in companion dogs.