Effect of Potassium on Ram Spermatozoa Studied by a Flow Dialysis Technique

Summary. The continuous flow dialysis apparatus (cfda) has been used to investigate the importance of potassium for the maintenance of the activity of ram spermatozoa. Ram spermatozoa contain 136 mg K+/100 g and the seminal plasma 78 mg K+/100 g. When semen is diluted one in three with a phosphate diluent, there is a rapid fall in the potassium concentration within the spermatozoa. Dialysis in the cfda causes a further exponential fall unless potassium is included in the dialysis fluid. Unless the phosphate buffer used in the cfda contains potassium ions, there is a sudden decrease in the impedance-change frequency (icf) between 3 and 5 hr from the start of dialysis. Washing or keeping unwashed spermatozoa for 2 hr prior to dialysis does not alter this response or the time of dialysis at which it takes place. Semen diluted one in three with fresh seminal plasma or with plasma obtained from stored semen gave the same response (fall in icf). The decline in icf due to the absence of potassium was less rapid when undiluted semen was used. Semen washed with a bicarbonate buffer had a lower initial icf than semen washed with phosphate, but the icf declined more slowly, and in the absence of potassium there was no sudden drop in the icf. Samples with potassium maintained a higher icf than those without. The most marked potassium effect was obtained under aerobic conditions using a phosphate fluid containing fructose, lactate or acetate. Under anaerobic conditions the presence of potassium ions in the dialysis fluid had little or no effect on icf.