Fig. 3. The effect of temperature and stimulus change on (A) the peak current density of L-type Ca²⁺ channel current (I_Ca) and (B) the charge density of I_Ca in trout atrial myocytes. Dissimilar letters indicate significant effects of temperature within each stimulus treatment (analysis of variance, Student—Newman—Keuls test). ^* indicates a significant decrease in I_Ca during AP stimulation at all temperatures and with each successive stimulus protocol at 21°C. indicates greater I_Ca charge density at 7°C during AP stimulation compared with SQ stimulation. Values are means ± S.E.M.; N=7 for 7°C and 21°C, and N=8 for 14°C.