INTRACELLULAR CALCIUM MEASUREMENTS IN INDIVIDUAL HUMAN SPERM DEMONSTRATE THAT THE MAJORITY CAN RESPOND TO PROGESTERONE

Objective: To determine if human spermatozoa could be immobilized and intracellular calcium measurements made on individual cells to measure what proportion can respond to P. Design: Spermatozoa were loaded wit h Fura 2 (Sigma Chemical Co., Poole, Dorset, United Kingdom) and suspe nded in 10% gelatin at 37 degrees C. A thin layer of the suspension wa s cooled to room temperature (20 degrees C to 25 degrees C) and [Ca2+] (i) was measured with a fluorescence microscope equipped with dual wav elength excitation and an image analysis system. Setting: University-b ased laboratory. Participants: Semen was obtained from four fertile do nors to a donor insemination program. Interventions: None. Main Outcom e Measures: [Ca2+](i) was calculated from the ratio of Fura 2 fluoresc ence excited at 340 nm and that excited at 366 nm. Results: One hundre d six of 114 sperm examined (93%) demonstrated a significant response to P but the size and duration of the response was variable. Conclusio n: These data demonstrate that most sperm can respond to P.