Figure 5. Iso infusion dramatically enhances β2a-dependent disease and death.

(A) Kaplan-Meier curves of control tTA single-transgenic as well as low- and high-expressing DTG mice infused with Iso at 60 mg/kg/d for 14 days. (B) Fractional shortening assessment by echocardiography in control tTA single-transgenic and low-expressing DTG mice with Iso or PBS treatment. Only low-expressing DTG mice were used because 44% survived the 14 days of Iso treatment. Numbers indicate the number of mice analyzed in each group. *P < 0.05 versus control with PBS, ANOVA. (C) Histological assessment of cardiac ventricular pathology by Masson’s trichrome in control tTA single-transgenic and low-expressing DTG mice with Iso or PBS infusion for 14 days. (D) Histological assessment of Ca²⁺ deposits in myocytes by von Kossa staining in control tTA single-transgenic and low-expressing DTG mice with Iso or PBS infusion for 14 days. Original magnification, ×200 (C); ×40 (D). (E) Quantitation of fibrotic area (blue) from trichrome-stained cardiac histological sections. Numbers indicate the number of mice analyzed in each group (10 photographs quantified per mouse heart). *P < 0.05 versus PBS-infused control, ANOVA. (F) Quantitation of areas of myocytes with Ca²⁺ deposits in control tTA single-transgenic and low-expressing DTG mice with Iso or PBS infusion for 14 days. *P < 0.05 versus PBS-infused DTG, Student’s t test.