Fig. 1.

Selective phosphodiesterase 4 (PDE4) inhibition with rolipram increases Ca²⁺ spark frequency in freshly isolated detrusor smooth muscle (DSM) cells. (A) An image of a freshly isolated DSM cell loaded with fluo-4-AM. The white line passing the active site a is the laser beam scanning pathway (1-pixel width). (B) A three-dimensional view of the recordings illustrating the relative fluorescence intensity profiles of the Ca²⁺ sparks. The color scale indicates the relative fluorescence intensity F/F₀. (C) Summary data illustrating that rolipram (10 µM) increased the Ca²⁺ spark frequency without a significant change of Ca²⁺ spark amplitude (n = 15, N = 9; *P < 0.05). Amp, amplitude; Freq, frequency.