Fig. 4. Acceleration of flagellar beat frequency by bicarbonate. (A,B) In a large-scale experiment, 90 cells from a single animal were selected randomly for examination 1-10 minutes after addition to medium Na7.4 containing 0 () or 15 () mM NaHCO₃. Beat frequency (A) and amplitude (B) were determined by waveform analysis as described in Fig. 3. Horizontal bars mark the mean, enclosed by boxes that extend ±1 s.d. (C-E) Beat frequencies extracted from sperm images collected during perfusion by medium Na7.4 with 0 (, ), or with Na7.4 containing 1 (), or 15 (•) mM NaHCO₃ as indicated. Data were averaged from triplicate experiments each involving three cells from one animal (n=9). Error bars that were smaller than the symbol were deleted for clarity. In C, half times were 8.8±0.2 and 17.5±0.4 seconds for the indicated bestfit sigmoidal curves.

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