Fig. 3. Spontaneous f_H of 5°C, normoxia- and anoxia-acclimated right-atrial preparations during exposure to various saline solutions devised to simulate or reverse the changes occurring in turtle blood plasma during 14 days of anoxic submergence. Exposure order for normoxia-acclimated preparations was as given in the figure, reading from left-to-right, whereas exposure order for anoxia-acclimated preparations was as reading from right-to-left. Significant differences (P<0.05) in f_H among saline solutions within an experimental group are indicated by different letters. Significant differences (P<0.05) in f_H from a comparable Control protocol f_H. ^*Significant difference (P<0.05) in f_H between normoxia- and anoxia-acclimated preparations under simulated in vivo normoxic or simulated in vivo anoxic conditions. Values are means ± s.e.m.; N=6 in both experimental groups.