Skip to main content
. 2018 Jul 16;9:841. doi: 10.3389/fphys.2018.00841

Figure 2.

Figure 2

Influence of sequential administration of atropine and propranolol, and drug order effects, on heart changes in sedentary and exercised mice. Representative changes in HR following sequential administration of atropine (A) (2 mg/kg) and propranolol (P) (10 mg/kg) in two opposite orders (i.e., AP and PA) are shown. Two-way ANOVA indicated a significant main effect for drug (P < 0.0001, all groups) and interaction between drug and order (P < 0.0007 in all groups), with no effect of order observed (P > 0.14, all groups). In all groups, atropine had a larger effect (i.e., 1.5-to-2-fold) (P < 0.0001) on HR increase when administered in the absence compared to the presence of propranolol. In contrast, propranolol had a larger effect (i.e., 1.5-to-2-fold) (P < 0.0001) on HR when administered after atropine. These results are indicative of “accentuated antagonism.” Solid circles (•) indicate the atropine-propranolol (AP) sequence, while open circles (°) indicate the propranolol-atropine (PA) sequence. Data are given as means ± SD.