Fig. 1. Percent change in transmitted light through a fingertip (LTF), change in systolic blood pressure (SBP), and change in heart rate (HR) in volunteers with the II ( thin line ) and DD ( thick line ) genotypes during and for 20 min after administration of dexmedetomidine. Data are expressed as mean values from all subjects. An increase in transmitted light represents a decrease in finger blood volume (vasoconstriction). The vertical lines mark the beginning of each step increase and end in the infusion of dexmedetomidine.