The effects of thiopentone and propofol on human myometrium

Abstract

In this study, the effects of thiopentone and propofol on pregnant human myometrial contraction strength and tonus were investigated in vitro. Myometrial strips were stimulated by 1000 mU/L oxytocin, then thiopentone (10-8-10-4 M) or propofol (10-8-10-4 M) were added to organ bath comulatively. At 10-8 M, both thiopentone and propofol did not produce any effect on contraction strength. Thiopentone (10-7-10-4 M) decreased this parameter by 2.0 ± 1.3%, 11.1 ± 4.0%, 23.8 ± 3.3%, and 69.0 ± 5.0% at given doses respectively. At the same concentration range (10-7-10-4 M) the decrease in the concentration strength was found as 3.5 ± 2.0%, 12.8 ± 4.5%, 23.2 ± 6.5%, 45.8 ± 8.9% with propofol, respectively. The difference between them was significant only at 10-4 M. Propofol decreased the myometrial tonus minimally at 10-6 M (1.5 ± 0.7%), its effect on this parameter was somewhat higher at 10-5 and 10-4 M (15.1 ± 3.2%, 28.3 ± 6.0%, respectively). At lower doses (10-8-10-6 M) thiopentone was found to have no effect on myometrial tonus. But it decreased this parameter by 3.3 ± 2.1% and 20.8 ± 0.8% at 10-5 and 10-4 M, respectively. The results have suggested that the effect of propofol on myometrial contraction strength and tonus was less pronounced than thiopentone at clinically achieved concentrations (3 x 10-6 M-8 x 10-6 M for propofol, 4.5 x 10-5 M-10-4 M for thiopentone).