Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensitive K+ (KATP) channel is involved in ischemic p...Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensitive K+ (KATP) channel is involved in ischemic preconditioning. Methods Single myocytes were isolated from the ventricle of adult guinea pigs. The experimental chamber allowed the cells to be exposed to low O2 pressure. During hypoxic preconditioning, the cells were equilibrated with normaxic solution for 10 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of reoxygenation. The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation. Ionic currents were studied with the patch clamp technique in whole-cell and cell-attached configurations. Results A 5-minute hypoxic preconditioning offered a significant protection from cell injury in subsequent hypoxia-reoxygenation. After a latency of more than 15 minutes, hypoxia induced a time-independent outward K+ current which could be blocked by 5?μmol/L glibenclamide. At 10?mV, the current increased from 78±15?pA to 1581±153?pA (P<0.01, n=18). However, the latency to develop KATP channel currents (IKATP) was greatly shortened in preconditioned cells, and the current was increased acceleratively. At 10?mV, the current more than 4?nA was recorded in preconditioning cells. In the single channel recordings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells. Conclusion Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia. This hypoxic preconditioning may modify the KATP channel, and make the channel open more readily during the second hypoxia.展开更多
Objective: This study aimed at understanding of the role of calcium homeostasis in cardiomyocytes from hypoxia, burnt serum induced injury. Methods: Alterations in cytosolic free calcium concentration (Ca i), c...Objective: This study aimed at understanding of the role of calcium homeostasis in cardiomyocytes from hypoxia, burnt serum induced injury. Methods: Alterations in cytosolic free calcium concentration (Ca i), calcium influx and viability of the cardiomyocytes in vitro after hypoxia, burnt serum stimulus were observed. Results: Ca i increased markedly, in the meantime, the cellular transmembrane calcium influx increased and the viability of the cells decreased significantly following hypoxia, burnt serum induced injury. Conclusions: In our study cytosolic calcium ion was transported abnormally in the cardiomyocytes after burn, to result in Ca i increase and runaway calcium homeostasis, thus the normal cellular function was disturbed. This may be one of the important factors in the development of burn induced cardiac injury.展开更多
基金theLeadingSpecialityFundingsof Shanghai! (No 94 Ⅲ 0 0 1)
文摘Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensitive K+ (KATP) channel is involved in ischemic preconditioning. Methods Single myocytes were isolated from the ventricle of adult guinea pigs. The experimental chamber allowed the cells to be exposed to low O2 pressure. During hypoxic preconditioning, the cells were equilibrated with normaxic solution for 10 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of reoxygenation. The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation. Ionic currents were studied with the patch clamp technique in whole-cell and cell-attached configurations. Results A 5-minute hypoxic preconditioning offered a significant protection from cell injury in subsequent hypoxia-reoxygenation. After a latency of more than 15 minutes, hypoxia induced a time-independent outward K+ current which could be blocked by 5?μmol/L glibenclamide. At 10?mV, the current increased from 78±15?pA to 1581±153?pA (P<0.01, n=18). However, the latency to develop KATP channel currents (IKATP) was greatly shortened in preconditioned cells, and the current was increased acceleratively. At 10?mV, the current more than 4?nA was recorded in preconditioning cells. In the single channel recordings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells. Conclusion Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia. This hypoxic preconditioning may modify the KATP channel, and make the channel open more readily during the second hypoxia.
文摘Objective: This study aimed at understanding of the role of calcium homeostasis in cardiomyocytes from hypoxia, burnt serum induced injury. Methods: Alterations in cytosolic free calcium concentration (Ca i), calcium influx and viability of the cardiomyocytes in vitro after hypoxia, burnt serum stimulus were observed. Results: Ca i increased markedly, in the meantime, the cellular transmembrane calcium influx increased and the viability of the cells decreased significantly following hypoxia, burnt serum induced injury. Conclusions: In our study cytosolic calcium ion was transported abnormally in the cardiomyocytes after burn, to result in Ca i increase and runaway calcium homeostasis, thus the normal cellular function was disturbed. This may be one of the important factors in the development of burn induced cardiac injury.
