Fig. 3

Changes in the olfactory bulb blood flow following nicotine administration or hypercapnia in aged rats. a Graph of the time course of regional blood flow responses in the olfactory bulb ipsilateral to the olfactory nerve stimulation. The blood flow values were averaged every 1 s before (black line) and after (red line) nicotine injection (30 μg/kg). The stimulus frequencies used were 2 Hz (upper graphs) and 20 Hz (lower graphs). Changes in regional blood flow are expressed as percentages of the corresponding basal values (the mean value from those recorded over the 10 s before time zero). Each point and vertical bar represent a mean ± SEM (n = 5). b Graph of olfactory bulb regional blood flow response time courses, averaged every 1 s (n = 5). *p < 0.05, **p < 0.01: significantly different from the mean pre-stimulus basal value (− 1 to 0 s), determined with a Friedman’s test followed by Dunn’s multiple comparison test