Fig. 3. Change in twitch and tetanic force developed by indirect stimulation with a change in temperature. Twitch (open circles) and tetanic (closed circles) forces are expressed relative to the respective forces obtained by direct stimulation. Values are means ± S.D. The figures at each data point denote the number of samples used. The small letters (a, b and c) in twitch denote that the differences between points are statistically significant (P<0.01), while the differences in tetanus are not significant.