ADRB2 and Tremor: Our findings that propranolol does not affect gross locomotor behavior in control, Car8wdl/wdl, or β1-AR−/−;β2-AR−/− mice in open field and footprinting assays—and especially that propranolol does not affect ataxic gait parameters in Car8wdl/wdl mice—supports the hypothesis that propranolol and its mechanisms are specific to tremor pathophysiology.