The Change Of Persistent Sodium Current In Ventricular Myocyte During Hypoxia-early Reoxygenation And Mechanisms During Hypoxia

Objective: To investigate the effect of hypoxia-early reoxygenation on persistent sodium current(INap) in single ventricular myocytes of guinea pig and discuss its role and significance during this pathological condition.Methods: The whole cell patch clamp technology was used to record this current and study its change under the condition of hypoxia-reoxygenation model.Result: (l)With 0.5Hz,1Hz and 2Hz pulse frequency, the current density gap between the first and the eighth pulse of INap is 0.021+0.014, 0.097+0.014 and 0.133+0.024pA/pF ( P<0.001) respectively. (2) Depolarization with membrane holding potential of -150--80mv respectively, InaP density attenuate gradually. (3) The amplitude of INaP is increased consistently with the prolongation of hypoxia time during hypoxia. (4) INaP is 0.500+0.125,1.294+0.321 and 0.988+0.189pA/pF(P<0.001 Muring normoxia, hypoxia after 15min and reoxygenation after 5min respectively.Conclusion: INaP is pulse frequency-dependence and membrane potential-dependence, and its amplitude is increased by hypoxia and recovered by reoxgenation, but still higher than control. These results indicate that INaP has great significance in arrhythmogenesis and calcium-overload, which causes the following postischemia and posthypoxia myocardial damage.