Fig. 3. (A) Change in relative ventricular mass in warm-acclimated rainbow trout induced by four phenylhydrazine hydrochloride injections at weeks 0, 2, 4 and 6 (solid line and triangles) compared with sham-injected control fish receiving saline (solid line and circles). The dotted lines represent the recovery periods. Mean values ± s.e.m. at weeks 0, 2, 4, 6, 8 and 12 represent N=6 fish. ⁺Significant difference (P<0.05) from the pre-treatment control value at week 0, as detected by ANOVA and Dunnett's test. ^*Significant difference (P<0.05) between a time-matched PHZ-treated and sham-injected group, as determined by Student's t-test statistic (P<0.05). (B) A linear relationship exists between wet and dry rM_V, indicating constant water content among treatment groups.