Pharmacological profile of purinergic signals in the intact seminiferous epithelium. (A) Representative fluorescence images (left) and merged photomicrographs (IR-DIC and fluorescence; right) of acute transverse seminiferous cord slices. A putative Sertoli cell (red; top) and two putative spermatogonia (green, bottom), likely connected by a cytosolic bridge, are diffusion loaded with fluorescent dyes during whole-cell patch-clamp recordings. (B and C) Representative whole-cell voltage-clamp recordings (V_hold = −40/−80 mV; S₁, S₅) from putative Sertoli cells (red) and spermatogonia (green). Cells are exposed for 3 s to low (10 µM; B) and high (1 mM; C) concentrations of ATP in the absence or presence of suramin (10 µM; B) or A-438079 (10 µM; C), respectively (preincubation = 120 s). (D) Bar graph depicting response amplitudes (means ± SEM) in the presence of suramin or A-438079. Signals are normalized to currents triggered before pharmacological treatment. Putative cell types are color coded. Numbers of cells as shown above bars. Asterisks (*) denote statistical significance, P < 0.05 (paired t tests).