Electrophysiology in Action

The present research was designed to elucidate the effects of intravenous anaesthetic propofol (30 µM) alone, and in combination with B1, B2 - adrenomimetic isoprenaline (5 nM) on cardiac Ca2+ and K+ ion channels. Voltage clamp techniques - "sharp" microelectrodes and "switched" voltage clamp method were used to measure calcium current, ICa, and potassium currents, IK. In the first experiments a long duration experimental protocol was used in which propofol (30 µM) caused a decrease in ICa, but under these conditions the effects appeared not to be reversible. In contrast, when a shorter protocol was used, propofol (30 µM) again decreased ICa (a decrease to 30%), but in these experiments the effects of propofol were reversible. The reduction in ICa was 30 +/- 5 %, n = 6 cells, measured at +10 mV. Propofol (30 µM) also decreased IK measured at +40 mV (an effect that was probably predominantly on IKs). The effects of propofol on IK were reversible. Experiments with isporenaline were difficult to interpret. The effects of isoprenaline (5 nM) on ICa and IK were unexpectedly small and the effects of propofol in the presence isoprenaline were also statistically insignificant