FIGURE 3.

Acceleration of the flagellar beat by A3R agonist Cl-IB-MECA. Individual wild-type sperm were perfused for 120 s with Medium HS containing 0–30 μm Cl-IB-MECA as indicated, then for 45 s with HS fortified with 15 mm NaHCO₃. Shown are mean beat frequencies for cells sampled at 0, 30, 60, 90, 120, and 165 s (n = 24–36 cells in three independent experiments). Mean acceleration determined by regression analysis of the initial 60 s of response was 0.08 ± 0.05, 2.3 ± 0.9, 2.8 ± 1.1, and 4.8 ± 1.0 Hz min⁻¹. Perfusion with 30 μm Cl-IB-MECA for 90 s increased beat frequency significantly (p = 0.021).