BACKGROUND: Cardiovascular instability after induction of intravenous anesthetics may be explained partly by direct negative inotropic effects. We studied the effects of etomidate and propofol on the inward calcium currents (ICa) of rat ventricular myocytes using the whole-cell voltage-clamp technique. METHODS: ICa was elicited by progressively depolarizing cells from -40 to -50 mV. The peak amplitude of ICa was measured before, during and after the administration of equimolar concentrations of etomidate and propofol. RESULTS: Exposure to etomidate and propofol produced a concentration-dependent inhibition of ICa.; 1, 10, 100 and 300 micrometer of etomidate decreased the peak ICa (mean +/- SEM) by 14.5 +/- 6.3, 25.9 +/- 9.4, 31.9 +/- 12.1, 42.5 +/- 8.8% and 1, 10, 100 and 300 micrometer of propofol decreased the peak ICa by 15.7 +/-3.4, 21.3 +/-2.5, 59.2 +/-2.0, 69.9 +/-2.8%, respectively. COCLUSIONS: These results suggest that etomidate and propofol have a direct negative inotropic effect via inhibition of inward calcium currents in rat ventricular myocytes.