Fig. 7. Effects of various compounds (iodoacetate, (IAA; 0.4 mmol l^-1); ryanodine, (Ryn; 10 µmol l^-1); caffeine (8 mmol l^-1); Ca²⁺ (5 mmol l^-1); epinephrine (Epi; 1 µmol l^-1); testosterone (T; males; 0.3 µmol l^-1); or 17ß-estradiol (E2; females; 1.0 nmol l^-1) on post-rest potentiation (PRP) in immature males (A) and females (B). In both sexes, ventricle strips receiving glucose had higher PRP than strips without glucose (^*P<0.05). Control strips containing glucose also exhibited higher PRP than all other treatments when glucose was present (a denotes P<0.05). PRP for glucose-free, control strips were higher than all other treatments (b denotes P<0.05). However, other than control strips, no significance was observed between glucose vs glucose-free treatments (P=0.34). Values are means ± s.e.m. (N=6-11 strips per group).