Objective To understand the effects of etomidate and midazolam on isolated rabbit pulmonary arteries and the
possible interaction with functional
endothelium.Methods The pulmonary artery rings were prepared with endothelium intact and endothelium denuded.Direct effects of two drugs
cumulative concentration on the baseline tone and that precontracted by NE,and influences of two drugs(1mmol/L)on the cumulative concentration response curves of NE were assessed.Results The cumulative concentrations of two drugs from 0.03mmol/L to 3.0mmol/L had no influences on the baseline tone.The artery rings precontracted by NE were vasodilative with dose dependent and endothlium independent way.Two drugs (1mmol/L) made the cumulative concentration response curves of NE shift to right in nonparalled way,the contractile amplitude of pulmonary artery rings was significantly lower than that of NE control(P<0.05).Conclusion Etomidate and midazolam have no influences on the baseline tone of isolated rabbit pulmonary artery rings,vasodilative responses appear in the artery rings precontracted by NE with endothelium independent way.Two drugs may inhibite the contractile effects of NE on pulmonary artery in non competitive way.