Figure 10.

A standard curve was generated for the detection of cAMP levels in stallion sperm samples with a good linearity of detection in the range of 0.08—20 pmol/ml. (B) Mean intracellular cAMP levels in stallion spermatozoa incubated in NCM, CM, CM—NaCl, CM—Na⁺, CM + 25 mM NH₄Cl, CM at pH 7.9, CM + 1 mM caffeine, CM + 2.5–5–10–25–50 mM procaine, for 15 min (black bars) and 1 h (white bars). A procaine concentration-dependent effect on cAMP levels was observed. The highest cAMP level was measured in stallion spermatozoa exposed to caffeine. (C) Boar sperm suspensions incubated in NCM, CM, and CM + 1 mM caffeine. In general, cAMP levels were much higher in boar than stallion sperm after incubation in CM and CM + 1 mM caffeine at 15 min and 1 h. Data represent mean (±SD) cAMP concentration of a suspension of 5 × 10⁶ spermatozoa/ml over three replicates using three different stallions. Within time-point 15 min, values that differ significantly (P < 0.05) are indicated by different small letters. Within time-point 1 h, values that differ (P < 0.05) are indicated by different capitals.