POTASSIUM-DEPENDENT INCREASES IN CYTOSOLIC PH STIMULATE METABOLISM AND MOTILITY OF MAMMALIAN SPERM
POTASSIUM-DEPENDENT INCREASES IN CYTOSOLIC PH STIMULATE METABOLISM AND MOTILITY OF MAMMALIAN SPERM
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DOI：
10.1073/pnas.80.5.1327
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
LARDY, HA
中科院分区：
文献类型：
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作者：
BABCOCK, DF;RUFO, GA;LARDY, HA
精子胞质pH值，由细胞内的羧基荧光素的光谱特性，是迅速下降的扩散和随后的解离的不带电的弱酸性磷酸，乳酸或羟基丁酸和增加扩散和随后的细胞内质子化的弱碱NH3。当向悬浮于120 mM NaCl培养基中的精子中加入50 mM NH 4Cl使细胞内pH升高约6.8-6.9时，代谢和动力学活性显著增加。在相当的添加50 mM Li+或K+或当培养基的pH从6.5增加到8.2时，未观察到呼吸刺激。在使用120 mM KCl的培养基中，将外部pH增加至7.8-8.2导致代谢和动力学活性增加，与磷酸二酯酶抑制剂咖啡因诱导的最大刺激相当。在碱性培养基中，随着KCl诱导的呼吸刺激，细胞溶质pH从6.3-6.6增加到6.8。加入咖啡因后胞浆pH值无变化。AMP依赖性蛋白激酶活性比，在细胞提取物中测定，增加咖啡因治疗，但不升高120 mM KCl，碱性pH值或其组合。细胞溶质pH在哺乳动物精子的运动和代谢的调节中起作用，其不由cAMP介导，但可能在质膜电压依赖性质子通道的控制下。从精子膜制备的囊泡的H+通量不受跨囊泡K+浓度梯度的大小变化的影响。
Sperm cytosolic pH, determined by the spectral properties of intracellular carboxyfluorescein, is decreased rapidly by the diffusion and subsequent dissociation of the uncharged weak acids pyruvic, lactic or hydroxybutyric and is increased by diffusion and subsequent intracellular protonation of the weak base NH3. Metabolic and kinetic activity increases dramatically when intracellular pH is elevated about 6.8-6.9 by addition of 50 mM NH4Cl to sperm suspended in a 120 mM NaCl medium. Respiratory stimulation is not observed upon comparable additions of 50 mM Li+ or K+ or when the pH of the medium is increased from 6.5 to 8.2. Increases of the external pH to 7.8-8.2 in medium employing 120 mM KCl result in increased metabolic and kientic activity, comparable to the maximal stimulation induced by the phosphodiesterase inhibitor caffeine. An increase in cytosolic pH from 6.3-6.6 to 6.8 occurs concomitant with the respiratory stimulated induced by KCl in alkaline media. No change in cytosolic pH follows addition of caffeine. AMP-dependent protein kinase activity ratios, determined in cellular extracts, are increased by caffeine treatment but are not elevated by 120 mM KCl, by alkaline pH or by their combination. Cytosolic pH plays a role in the regulation of motility and metabolism of mammalian sperm that is not mediated by cAMP but that may be under control of a plasma membrane voltage-dependent proton channel. H+ fluxes across vesicles prepared from sperm membranes are unaffected by variation in the magnitude of the transvesicular K+ concentration gradient.