Effects of isoprenaline on delayed rectifier potassium current in isolated guinea pig ventricular myocytes.
OBJECTIVE
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.


CONCLUSIONS
There were two components of Ik, one of which was modulated by Iso and intracellular Ca2+.
Cui
Y
Y
Department of Pharmacology, Fourth Military Medical University, Xi-an, China.
Zhao
D H
DH
D000818:Animals; D002118:Calcium / Q000502:physiology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008839:Microelectrodes; D009206:Myocardium / Q000166:cytology; D015221:Potassium Channels / Q000187:drug effects*
D015221:Potassium Channels; D007545:Isoproterenol; D002118:Calcium