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Effects of isoprenaline on delayed rectifier potassium current in isolated guinea pig ventricular myocytes
Aim:
To study the effects of isoprenaline (Iso) on the delayed rectifier potassium current (Ik) in isolated guinea pig ventricular myocytes.
Methods:
Single cells were isolated from guinea pig ventricle. Ik was studied under voltage clamp conditions.
Results:
When Ik was activated by depolarizing pulses to +40 mV of increasing duration (40-300 ms), Iso 1 mumol . L-1 caused an enhancement in Ik which was larger for longer pulses (150-300 ms). This was also seen when the intracellular calcium was buffered by 1,2-bis(2-aminophenoxy) ethane-N, N, N1, N1-tetraacetic acid (BAPTA). Intracellular application of BAPTA caused a decrease in Ik activated by longer pulses.
Conclusion:
There were two components of Ik, one of which was modulated by Iso and intracellular Ca2+.