system
Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Aging, Animals, Apoptosis, Caspase Inhibitors, Cells, Cultured, Chromones, Hypoxia, In Situ Nick-End Labeling, Ischemic Preconditioning, Myocardial, Male, Morpholines, Myocardial Reperfusion Injury, Myocytes, Cardiac, Protein Tyrosine Phosphatase, Non-Receptor Type 1, Proto-Oncogene Proteins c-akt, RNA, Small Interfering, Rats, Rats, Wistar, Up-Regulation, Vanadates.
user
Does small interference RNA against PTP-1B reduce hypoxia/reoxygenation induced apoptosis of rat cardiomyocytes? Context: To investigate the effect of siRNA against PTP-1B on neonatal rat cardiac myocyte apoptosis induced by hypoxia-reoxygenation (H/R) and its molecular mechanisms. Isolated neonatal and adult rat cardiac myocytes were cultured for 24 h after PTP-1B siRNA transfection, and with 2, 4 and 6 h of hypoxia followed by 6 h of reoxygenation (H/R). The cardiac myocyte apoptosis induced by the treatments was assessed by TUNEL staining. Levels of PTP-1B and phospho-Akt were determined by Western blot, colorimetric assay kits were used to measure activities of caspase-3 and 8, and co-immunoprecipitation was used to check the amount of PTP-1B bound to FasR. Sodium orthovanadate, a general pharmacological phosphatase blocker and LY294002, an inhibitor of PI3-kinase/Akt pathway, were respectively used to inhibit PTP-1B and Akt activity. H/R resulted in severe injury in cultured rat cardiomyocytes and upregulated PTP-1B expression. However, siRNA against PTP-1B significantly decreased the number of apoptotic cardiomyocytes induced by 4H/6R as compared with cells without siRNA treatment (Apoptotic index: 12.1 +/- 1.4% vs. 23.2 +/- 1.6%, P < 0.05), along with greater phosphorylation of Akt, reduced activities of caspase-3 and 8, and the lower association of PTP-1B with FasR. Vanadate and LY294002 also partly reduced apoptosis of cardiomyocytes induced by 4H/6R.
assistant
PTP-1B is a key regulator of apoptosis of cardiomyocytes induced by H/R, and siRNA against PTP-1B effectively protects cardiomyocytes against H/R injury, the mechanisms of which might be associated with Akt activation, the reduction of both caspase-3 and 8 activities, and the lower amount of PTP-1B bound to FasR. Final Decision: yes