Inskeep P B, Hammerstedt R H
Biol Reprod. 1982 Oct;27(3):735-43. doi: 10.1095/biolreprod27.3.735.
Differences in the metabolism of testicular and cauda epididymal sperm have been demonstrated for several species, but the region(s) of the ram epididymis in which changes in metabolism occur is not known. In these experiments respirometric and radioisotopic methods were used to monitor metabolic activity of ram sperm isolated from six regions of the epididymis. Effects of exogenous carnitine on metabolism of the sperm also were studied. Sperm from the caput and corpus epididymidis had similar rates of glucose and oxygen consumption and of lactate and CO2 production. However, the magnitude of each parameter was severalfold higher for cauda sperm. In addition, cauda sperm produced 25 times more acetate than caput or corpus sperm. The amount of energy derived from utilization of endogenous substrates was similar for sperm from all regions of the epididymis. Exogenous D,L-carnitine (5 mM) had no effect on the metabolism of caput or corpus sperm. However, when cauda sperm were incubated with carnitine, they consumed less glucose and produced less lactate and more acetate; thus they produced the same amount of ATP from less glucose than did control aliquots incubated without exogenous carnitine. Since the rate of ATP synthesis was equivalent for both incubations, we believe this change in metabolism reflects an increased efficiency of glucose utilization. This increased efficiency may be vital for sperm motility.
几个物种的睾丸精子和附睾尾精子在代谢方面的差异已得到证实，但尚不清楚公羊附睾中发生代谢变化的区域。在这些实验中，采用呼吸测定法和放射性同位素法监测从附睾六个区域分离出的公羊精子的代谢活性。还研究了外源性肉碱对精子代谢的影响。附睾头和附睾体的精子在葡萄糖和氧气消耗以及乳酸和二氧化碳产生方面具有相似的速率。然而，附睾尾精子的每个参数值要高出几倍。此外，附睾尾精子产生的乙酸盐比附睾头或附睾体精子多25倍。附睾所有区域的精子利用内源性底物产生的能量相似。外源性D，L-肉碱（5 mM）对附睾头或附睾体精子的代谢没有影响。然而，当附睾尾精子与肉碱一起孵育时，它们消耗的葡萄糖减少，产生的乳酸减少，产生的乙酸盐增多；因此，与未添加外源性肉碱孵育的对照等分试样相比，它们从较少的葡萄糖中产生了相同量的ATP。由于两种孵育条件下ATP合成速率相同，我们认为这种代谢变化反映了葡萄糖利用效率的提高。这种提高的效率可能对精子活力至关重要。
