DEFECTIVE CALCIUM INFLUX AND ACROSOME REACTION (SPONTANEOUS AND PROGESTERONE-INDUCED) IN SPERMATOZOA OF INFERTILE MEN WITH SEVERE TERATOZOOSPERMIA

Objective: To evaluate the acrosome reaction and its prerequisite, a c alcium influx, in spermatozoa of infertile men with a high incidence o f abnormal sperm forms. Design: Prospective, controlled study. Setting : Academic tertiary assisted reproduction center. Patients: Patients ( n = 14) were allocated in the study after semen evaluation showed tera tozoospermia (<14% normal sperm forms) as diagnosed by strict criteria . Interventions: After swim-up separation of the motile fraction, acro some reactions were evaluated using Pisum sativum agglutinin (both spo ntaneously and exogenously induced with P and the calcium ionophore A2 3187, both at 10 mu M); the intracellular-free [Ca2+](i) was assessed by the fluorescent fura-2 indicator (basal and after P). Results: Pati ents did not show the typical P-induced wave of [Ca2+](i) that was obs erved in controls but rather a blunted response, no response at all, o r abnormal basal [Ca2+](i), levels. The percent of basal acrosome reac tion was significantly lower for patients versus controls postswim-up, and at 1 hour and 3 hours. Furthermore, there was a significant diffe rence in the response of acrosome reaction to P both at 1 hour and 3 h ours, with patients showing almost no response at all. However, patien ts' acrosome reaction response to the calcium ionophore was similar to those of fertile men. Conclusion: Infertile patients with a high inci dence of abnormal sperm forms as diagnosed by strict criteria have a l ow incidence of spontaneous acrosome reaction and a diminished P-stimu lated acrosome reaction, whereas the nonspecific response to a calcium ionophore is conserved. Parallel abnormalities of [Ca2+](i) were obse rved in patients, suggesting that these sperm populations may have a d efective nongenomic P sperm receptor and/or abnormalities of other mem brane transduction systems.