Figure 1. Effect of ketamine (10 micro Meter to 1 mM) on canine smooth muscle strips contracted with two different concentrations of the physiologic agonist acetylcholine. In strips contracted with 0.1 micro Meter acetylcholine (open circles, n = 6), ketamine caused a dose-dependent decrease in force. In strips contracted with 10 micro Meter acetylcholine (filled circles, n = 6), relaxation occurred only in response to 1 mM ketamine. Values are means +/- standard deviations.