Figure 10.

Echocardiography of double transgenic mice. Echocardiography of wild-type (WT), 5-HT₄-transgenic (5-HT₄-TG), PP2A-transgenic (PP2A-TG) and double transgenic (DT) mice. (A) Basal ejection fraction (Ctr) was reduced in PP2A-TG and DT mice, and 5-HT increased EF only in 5-HT₄-TG and DT mice. β-adrenergic stimulation by isoproterenol (Iso) increased EF less in PP2A-TG and DT compared to the other groups. (B) Basal heart rate (Ctr) was not different between genotypes, and positive chronotropic effects of 5-HT were only noted in 5-HT₄-TG and DT mice. However, β-adrenergic stimulation (Iso) increased heart rate in all groups. Numbers in bars indicate the numbers of mice studied. Data shown are means ± SEM. * p < 0.05 vs. Ctr; ^# p < 0.05 vs. WT.