RESUMO
N6-methyladenosine (m6A) is an abundant mRNA modification affecting mRNA stability and protein expression. It is a highly dynamic process, and its outcomes during postnatal heart development are poorly understood. Here we studied m6A machinery in the left ventricular (LV) myocardium of Fisher344 male and female rats (postnatal days one to ninety; P1-P90) using Western Blot. A downward pattern of target protein levels (demethylases FTO and ALKBH5, methyltransferase METTL3, reader YTHDF2) was revealed in male and female rat LVs during postnatal development. On P1, the FTO protein level was significantly higher in male LVs compared to females.
Assuntos
Miocárdio , Masculino , Feminino , Ratos , AnimaisRESUMO
Continuous normobaric hypoxia (CNH) renders the heart more tolerant to acute ischemia/reperfusion injury. Protein kinase C (PKC) is an important component of the protective signaling pathway, but the contribution of individual PKC isoforms under different hypoxic conditions is poorly understood. The aim of this study was to analyze the expression of PKCepsilon after the adaptation to CNH and to clarify its role in increased cardiac ischemic tolerance with the use of PKCepsilon inhibitory peptide KP-1633. Adult male Wistar rats were exposed to CNH (10 % O(2), 3 weeks) or kept under normoxic conditions. The protein level of PKCepsilon and its phosphorylated form was analyzed by Western blot in homogenate, cytosolic and particulate fractions; the expression of PKCepsilon mRNA was measured by RT-PCR. The effect of KP-1633 on cell viability and lactate dehydrogenase (LDH) release was analyzed after 25-min metabolic inhibition followed by 30-min re-energization in freshly isolated left ventricular myocytes. Adaptation to CNH increased myocardial PKCepsilon at protein and mRNA levels. The application of KP-1633 blunted the hypoxia-induced salutary effects on cell viability and LDH release, while control peptide KP-1723 had no effect. This study indicates that PKCepsilon is involved in the cardioprotective mechanism induced by CNH.
Assuntos
Adaptação Fisiológica/genética , Hipóxia/genética , Hipóxia/fisiopatologia , Proteína Quinase C-épsilon/genética , Animais , Sobrevivência Celular/efeitos dos fármacos , Hipóxia/enzimologia , L-Lactato Desidrogenase/metabolismo , Masculino , Traumatismo por Reperfusão Miocárdica/enzimologia , Traumatismo por Reperfusão Miocárdica/genética , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Proteína Quinase C-épsilon/antagonistas & inibidores , Proteína Quinase C-épsilon/biossíntese , Inibidores de Proteínas Quinases/farmacologia , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Ratos , Ratos WistarRESUMO
OBJECTIVE: Large prospective studies in dogs with healed myocardial infarction (MI) recently show a positive relation between heart rate variability (HRV) and sudden cardiac death. METHODS: We have done similar experiments in dogs and we studied HRV, ECG and body surface potential maps (BSPM) in 26 normal mongrel dogs (10-15 kg) and 12 dogs with an experimental MI (ligation of LAD). A two-channel 8 hours lasting ECG recording was performed in all conscious dogs. The 2nd recording was done in Penthobarbital anaesthesia (30 mg/kg). RESULTS: We have found sinus arrhythmia (SA) in all 26 conscious dogs. The anaesthesia suppressed the sinus arrhythmia and HRV via compensatory tachycardia and alterations in baroreflexes. The suppression of arrhythmia was also present in dogs with myocardial infarction. CONCLUSIONS: It is suggested, that HRV and SA in dogs depend on conscious state and anaesthesia. On the basis of our results we can anticipate that the most important for HRV is the present status of the sympathetic nerve. We suggest, that our results are an important finding for experimental arrhythmology. (Fig. 4, Ref. 24.)