Fig 4. Effects of 24–72 hr exposure to 5–50 μg/mL DEHP or 100 μM Wy-14,643 on frequency potentiation.

A, B) hESC-CM exhibited a positive frequency potentiation response in the presence of control (+12%), whereas DEHP-treated cells exhibited a relatively flat response (+4%). No significant differences between control and Wy-14,643 treatment were observed. C) DEHP-treated samples became increasingly more difficult to stimulate at higher pacing frequencies († stimulus does not elicit calcium transient). n ≥ 4.