Figure 7. The non-selective phosphodiesterase (PDE) inhibitor IBMX as well as PDE2 and PDE4 antagonists stimulate I_f and I_Ca,L in EDS cardiomyocytes.

A–C, the non-selective antagonist IBMX (200 μM; A), the PDE2 selective antagonist EHNA (30 μM; B) and the PDE4 antagonist rolipram (10 μM; C) stimulate both I_f and I_Ca,L in EDS cardiomyocytes. The same voltage protocol as in Fig. 6 was used. The insets display I_Ca,L at a more extended time scale. Due to the slight delay in the maximal response of I_f as compared with I_Ca,L and the fast run down of the latter, the I_Ca,L traces displayed in B and C were recorded prior to I_f. D shows that most of the EDS cardiomyocytes tested responded to PDE antagonist application with a stimulation of I_f and I_Ca,L. E shows that an increase in I_f density was also observed under these conditions.