OBJECTIVETo detect sperm plasma membrane integrity (PMI) of cigarette smoking infertile males using SYBR-14/ PI fluorescent staining and flow cytometry and investigate its clinical significance.

METHODSWe collected semen samples from 132 cigarette smoking infertile men and 70 normal fertile controls, the former divided into a heavy-smoker group (> 20 cigarettes a day, n = 68) and a light-smoker group (< or = 20 cigarettes a day, n = 64). We performed computer-assisted semen analysis of the semen samples, and determined sperm PMI by flow cytometry after rinsing with PBS and staining by SYBR-14/PI, the sperm with normal PMI indicated as the percentage of those emitting green fluorescence (SYBR-14+/PI- %), dead sperm as the percentage of those emitting red (SYBR-14-/PI+), and moribund sperm as the percentage of those emitting both green and red (SYBR-14+/PI+).

RESULTSBoth the heavy- and light-smoker groups showed significant differences in SYBR-14-/PI+ % and SYBR-14+/PI- % from the normal controls (P < 0.01 or P < 0.05). SYBR-14+/PI- % was remarkably lower, while SYBR-14-/PI+ % markedly higher in the heavy-smoker than in the light-smoker group (P < 0.05). There was a significant correlation between SYBR-14+/PI- % and sperm motility (r = 0.938, P = 0.000).

CONCLUSIONSYBR-14/PI fluorescent staining and flow cytometry analysis could quickly and exactly detect sperm PMI. Cigarette smoking reduces sperm PMI and consequently sperm motility, which might be an important factor of male infertility.