Figure 6. Muscle sympathetic nerve activity burst frequencies in response to the cold pressor test for all astronauts.

Data for individual astronauts (1-5) are depicted as the same line type in each panel as in Fig. 3. Individual and mean (•; ± s.e.m.) responses to the cold pressor test pre-flight (n = 5) and in-flight (n = 4). BL, baseline; CPT, the cold pressor test (mean data are shown every 30 sec); R, recovery (mean data are shown every 1 min). * P < 0.05 and ** P < 0.01, compared with baseline.