The solubility of CO₂ in boar seminal plasma

Abstract

It has been reported that boar seminal plasma has a high content of CO₂¹⁾ This study was carried out to examine the influences of temperture, shaking, and pH on the solubility of CO₂ in boar seminal plasma.
Semen was collected with manual method, and was cooled down to 5°C rapidly. Seminal plasma was obtained by centrifuging it (10, 000 rpm) for 20 minutes at 5°C. The amounts of CO₂ was measured with Warburg's manometric apparatus. The pH was measured with glass elec-trode pH meter. The contents of Na and K were measured with atomic absorption spectroscopy.
Experiment 1: Influences of temperatures (20°C and 37°C) and shaking (120 stokes/min.) on the liberation of CO₂ from seminal plasma were examined. Seminal plasma samples (3 ml) were incubated in Warburg flasks (about 20 ml content), and the amounts of CO₂ liberated were measured under the various conditions (Table 1). The liberation was stimulated by shaking or increasing the temperature. Fig. 1 shows the effect of KOH on the absorption of CO₂ liberated from seminal plasma. Seminal plasma samples were incubated in Warburg flasks containing 0.3 ml of 20 % KOH (with folded filter paper) or water in center wells. Vigorous liberation took place at early stage of incubation (Fig. 1; graph 1), hence KOH failed to absorb the liberated CO₂ completely and the pressure in gas phase rose in some cases (Fig. 1; graph 2). The sample shaken during the equilibration showed little liberation during the measuring (Fig. 1; graph 5), and the reading dropped from the start of measuring (Fig. 1; graph 6 and 7) this movement was due to the absorption of CO₂ which remained in gas phase, and not to the respiratory activities^{3), 4)} of seminal plasma.
Experiment 2: Influences of CO₂ liberation on the pH of seminal plasma were examined. The pH of seminal plasma rised with the increasing of the liberation of CO₂ (Fig. 2).
Experiment 3: Contents of CO₂ and pH of seminal plasma were measured before and after shaking (Table 2). The contents of Na and K were shown in Table 3. The coefficients of corr-elation between the measured values were caluculated (Table 4). Significant positive correlations were shown between pH and the contents of CO₂ and those of ions.
Experiment 4. Mcllvaine's phosphate buffer solutions (pH; 6.27.8) and 3 N H₂SO₄ were added to seminal plasma and their influences on the liberation of CO₂ were examined. The additions stimulated the liberation (Fig. 3).