Fig. 3. Effects of exogenous glucose on twitch force (F). During the 60 min equilibration period, ventricle strips were incubated in the absence of any exogenous substrate. In sexually maturing males, F increased during the experimental period with 5 mmol l^-1 glucose present, compared with 0, 1, 2 and 10 mmol l^-1 glucose, and was higher than that in immature males and females at all concentrations tested. F was also higher in immature males at 5 mmol l^-1 glucose compared with females and at all concentrations tested. In females, 5 mmol l^-1 glucose increased F compared with 0, 1 and 10 mmol l^-1 values. ^*P<0.05. Values are means ± s.e.m. (N=8-26 strips per group).