Objective To observe time dependent effects of simulated ischaemia on transient sodium currents (INa) of rat left ventricular myocytes, and the effects of atorvastatin on ischaemia INa.
Methods 30 Wistar rats were used for isolating left ventricular myocytes, which were randomly divided into two groups: ischaemia group (normal → simulated ischaemia) and statin group (normal → simulated ischaemia with 5 μmol/l atorvastatin). INa were recorded in normal condition (for control) by whole-cell patchclamp. Then in simulated ischaemia condition, INa were recorded from 3 to 21 min, monitored normalised peak currents every 2 min, and compared gate parameters between normal and simulated ischaemia (3 min) condition.
Results a. Normalised currents (at −40 mV), in ischaemia group, compared with normal (0.95±0.04), the currents in simulated ischaemia were increased to peak at 3 min (1.15±0.08, p 0.05, respectively), and decreased at 21 min (0.56±0.13, p 0.05). b. Gate parameters, from normal to simulated ischaemia condition at 3 min, membrane potential at 50% maximal activation (V1/2,a), offsetting of activation curve (Ka), membrane potential at 50% maximal inactivation (V1/2,i) and deinactivation constant (τ) were decreased (p<0.01, respectively) in ischaemia group, but offsetting of inactivation curve (Ki) were not changed; compared between two groups, Ki of statin group were decreased (p<0.05) and the decrease of τ value in statin group were less than ischaemia group (p<0.05).
Conclusions The effects of simulated ischaemia on INa are time dependent, while INa is transient increased at 3 min, and atorvastatin can depress this process.
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