Phospholipase A activity in seminal plasma of men attending an infertility clinic

Seminal plasma from 40 men attending an infertility clinic was analyzed for phospholipase A activity and compared with serum from 20 healthy blood donors. The imprecision of the method was acceptable and the overall coefficient of variation was 8.1%. A huge discrepancy existed between seminal plasma and blood serum with regard to phospholipase A activity, the former fluid displaying on average a 180-fold higher activity than the latter. Preincubation of seminal plasma for 1 h at 37 degrees C resulted in an even higher phospholipase A activity while the corresponding activity in serum remained unchanged by such a treatment. This suggested the existence of a zymogen form of phospholipase A in seminal plasma. A significant correlation existed between sperm concentration and phospholipase A activity in seminal plasma (r = 0.46; p less than 0.01) and preincubated seminal plasma samples from normozoospermic men displayed a significantly higher mean value than those of azoospermic men. Phospholipase A activity also correlated significantly to zinc concentration in seminal plasma (r = 0.67; p less than 0.001). 4-Bromophenacyl bromide was inhibitory to a certain extent, the inhibition being most evident in the samples with high phospholipase A activity. Dibucaine and quinacrine, known phospholipase inhibitors in other systems, had no inhibitory effects. Only 58% of the seminal plasma samples contained measurable amounts of triglycerides. No significant correlation existed between triglyceride concentration and phospholipase A activity, r = 0.11.