CHOLESTEROL AND PHOSPHOLIPID LEVELS OF WASHED AND PERCOLL GRADIENT CENTRIFUGED MOUSE SPERM - PRESENCE OF LIPIDS POSSESSING INHIBITORY EFFECTS ON SPERM MOTILITY

Levels of DNA, cholesterol, and phospholipids of mouse caudal epididym al and vas deferens sperm that were processed through simple washing a nd Percoll gradient centrifugation were measured. The DNA and choleste rol contents of washed sperm and Percoll gradient centrifuged (PGC) sp erm (DNA = 3.6 +/- 0.3 pg/sperm and 3.4 +/- 0.3 pg/sperm, respec tivel y; cholesterol = 0.219 +/- 0.057 nmole/mu g DNA and 0.224 +/- 0.030 nm ole/mu g DNA, respectively, for washed and PGC sperm) were not signifi cantly different from each other; however, the phospholipid level of P GC sperm was only one half of that of washed sperm (0.315 +/- 0.071 nm ole/mu g DNA versus 0.720 +/- 0.075 nmole/mu g DNA, respectively). The presence of 0.3% bovine serum albumin (BSA) in the culture medium use d in sperm washing did not change the cholesterol and phospholipid con tents of washed sperm. Similarly, the cholesterol and phospholipid lev els of washed sperm and PGC sperm that were further incubated in BSA-c ontaining medium for 30 min remained the same. Interestingly, substant ial amounts of lipids, as determined by the cholesterol and phospholip id levels, were released into the supernatants of the sperm washes, an d sperm needed to be washed at least twice to ensure their stable leve ls of cholesterol and phospholipids. The lipid mixture in the first sp erm wash supernatant was shown to have inhibitory effects on PGC sperm motility. (C) 1996 Wiley-Liss, Inc.