Fig. 5. Effect of microinjection of DAMGO into the caudal medullary raphe region on cardiorespiratory baseline variables in anesthetized and spontaneously breathing rats. All variables are presented as relative values normalized to the control represented by the dashed line. Data are presented as mean ± SE; n = 7. * P < 0.05, ** P < 0.01 between the data obtained before (control) and after DAMGO microinjection by paired t test. BP = mean arterial blood pressure; f = respiratory frequency; HR = heart rate; VE= minute ventilation; VT= tidal volume.