Vc. Baum et al., EFFECTS OF HALOTHANE AND KETAMINE ON ACTIVATION AND INACTIVATION OF MYOCARDIAL CALCIUM CURRENT, Journal of cardiovascular pharmacology, 23(5), 1994, pp. 799-805
We evaluated the effects of clinically relevant concentrations of halo
thane (1%) and ketamine (10(-4)M) on activation, inactivation, and rec
overy from inactivation of voltage-gated sarcolemmal calcium current (
I-Ca) in single guinea pig ventricular myocytes, using the whole cell
voltage clamp. Both anesthetics had qualitatively similar effects. The
potential at half-activation was shifted from -18 to -23 mV for halot
hane (p < 0.03) and from -17 to -21 mV for ketamine (p = 0.005). There
was no change in the slope of the activation curve for either anesthe
tic. The potential at half-inactivation was shifted from -29 to -40 mV
with exposure to halothane (p < 0.001) and from -27 to -33 mV (p < 0.
001) with exposure to ketamine. There was no change in the slope of th
e inactivation curve with either agent. The changes in time constant o
f recovery from steady-state inactivation with halothane did not reach
statistical significance (178 vs. 207 ms, p = 0.20) and was significa
ntly prolonged with exposure to ketamine (106 vs. 157 ms, p = 0.005).
The two anesthetics show parallel shifts in activation, inactivation,
and recovery from inactivation of I-Ca in ventricular myocardial cells
. These findings in normal ventricular myocytes may help interpret the
interactions of these anesthetics with other types of heart muscle, s
uch as ischemic and immature myocardium.