Figure 3. The effect of halothane applied during stimulation with acetylcholine or aluminum fluoride (AlF^4-) at a constant Ca²⁺concentration. (A,B) Representative recordings of the application of halothane on the contraction induced by 10 [micro sign]m acetylcholine plus 10 [micro sign]m guanosine triphosphate (GTP; A) or AlF^4-(1 mm NaF, 10 [micro sign]m AlCl³) plus 10 [micro sign]m GTP (B) at 0.3 [micro sign]m Ca²⁺. The degree of precontraction before the addition of halothane was not significantly different for the stimulants. (C) Halothane-induced percentage relaxation corrected for time from the initial force induced by acetylcholine or AlF^4-at 0.3 [micro sign]m Ca²⁺, with SD shown by vertical bars (n = 5). Halothane relaxed both contractions (*P < 0.05;**P < 0.01). However, the extent of relaxation was different for the stimulants (##P < 0.01). The effect on acetylcholine was approximately three times greater than the effect on AlF^4-.