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The morphology and size of spermatozoa make it difficult to study the functional properties of the plasma membrane, however, some studies have revealed the presence of a number of ion channels in this cell. We measured the calcium (Ca++) influx induced by depolarization of the plasma membrane and by venom isolated from the Chilean black widow spider ( Latrodectus mactans), and functional changes in the presence of either high potassium or total venom. Our results indicate that the venom increased the Ca++ influx, with an EC50 of 6.1 μg/mL and triggering the acrosome reaction in 43.26% of the cells. The application of potassium (10 mM K+) or total venom (10 μg/mL) did not affect the morphology or DNA stability of the sperm. The effects induced by high K+ and venom suggest that direct blocking of K+ currents alters the passive properties of the plasma membrane, leading to the entry of Ca++. These results show the importance of functional changes induced by depolarizing the spermatozoa and by venom. This venom possesses one or more molecules that may be used as pharmacological tools for studies on spermatozoa and have potential applications in reproductive biotechnology. [ABSTRACT FROM AUTHOR]

The morphology and size of spermatozoa hinder the study of the functional properties of the spermatozoa plasma membrane. However, some studies have revealed the presence of a number of ion channels in this cell. We set out to measure the endogenous currents and to study the effect of the venom of the Chilean black widow spider ( Latrodectus mactans). By patch-clamping bovine spermatozoa our results indicate the presence of an outwardly rectifying current, sensitive to changes in K+ concentration (30–140 mM) and to tetraethylammonium (TEA, 10–100 mM). The application of the venom (7.5 µg/ml) blocks these K+ currents and then alters the passive properties of the plasma membrane. This leads to the entry of Ca++, reflected by a change in basal fluorescent units (5±2 at 35±10 FAU). The Ca++ influx follows a reduction in the membrane conductance (control 22±2; venom 10±1 pS), as calcium channels open in accord with voltage dependence. [ABSTRACT FROM AUTHOR]

The morphology and size of spermatozoa make it difficult to study the functional properties of the plasma membrane, however, some studies have revealed the presence of a number of ion channels in this cell. We measured the calcium (Ca(++)) influx induced by depolarization of the plasma membrane and by venom isolated from the Chilean black widow spider (Latrodectus mactans), and functional changes in the presence of either high potassium or total venom. Our results indicate that the venom increased the Ca(++) influx, with an EC50 of 6.1 microg/mL and triggering the acrosome reaction in 43.26% of the cells. The application of potassium (10 mM K(+)) or total venom (10 microg/mL) did not affect the morphology or DNA stability of the sperm. The effects induced by high K(+) and venom suggest that direct blocking of K(+) currents alters the passive properties of the plasma membrane, leading to the entry of Ca(++). These results show the importance of functional changes induced by depolarizing the spermatozoa and by venom. This venom possesses one or more molecules that may be used as pharmacological tools for studies on spermatozoa and have potential applications in reproductive biotechnology.

The morphology and size of spermatozoa hinder the study of the functional properties of the spermatozoa plasma membrane. However, some studies have revealed the presence of a number of ion channels in this cell. We set out to measure the endogenous currents and to study the effect of the venom of the Chilean black widow spider (Latrodectus mactans). By patch-clamping bovine spermatozoa our results indicate the presence of an outwardly rectifying current, sensitive to changes in K(+) concentration (30-140 mM) and to tetraethylammonium (TEA, 10-100 mM). The application of the venom (7.5 microg/ml) blocks these K+ currents and then alters the passive properties of the plasma membrane. This leads to the entry of Ca(++), reflected by a change in basal fluorescent units (5+/-2 at 35+/-10 FAU). The Ca(++) influx follows a reduction in the membrane conductance (control 22+/-2; venom 10+/-1 pS), as calcium channels open in accord with voltage dependence.