Addition of 1mM Ca/EGTA complex (1:1 ratio) to an incubation medium containing 1.5mM Ca2+ produced a notable increase in the Ca2+ cyling in ejaculated bovine spermatozoa. Similar results were also obtained with the Ca/EDTA and Ca/EDTA complexes or with the heavy metal chelator DTPA (50μM). Ba2+, Ni2+ or Co2+ added at 0.1mM concentration abolished the stimulatory effect of the Ca/EGTA complex on Ca2+ cycling, whereas it did not affect the calcium movement in the absence of the calcium chelator complex. It is concluded that small amounts of these cations should be bound to the plasma membrane of bovine spermatozoa and inhibit the cellular calcium influx. 0.1 mM Cd2+ and NEM or 1mM diamide produced a calcium efflux from the spermatozoa together with an inhibition of cellular motility and an increase in glutamate-oxaloacetate transaminase release. Conversely the impermeant sulfhydryl reagent mersalyl caused a net calcium efflux but did not alter the cellular motility nor the transaminase release. It is suggested that the permeant thiol reagents could decrease the spermatozoal mobility by impairing the mitochondrial ATP-synthesis. © 1988.
Effects of calcium chelators, divalent cations and sulfhydryl reagents on calcium uptake and motility of bovine spermatozoa.
RUZZENE, MARIA;
1988
Abstract
Addition of 1mM Ca/EGTA complex (1:1 ratio) to an incubation medium containing 1.5mM Ca2+ produced a notable increase in the Ca2+ cyling in ejaculated bovine spermatozoa. Similar results were also obtained with the Ca/EDTA and Ca/EDTA complexes or with the heavy metal chelator DTPA (50μM). Ba2+, Ni2+ or Co2+ added at 0.1mM concentration abolished the stimulatory effect of the Ca/EGTA complex on Ca2+ cycling, whereas it did not affect the calcium movement in the absence of the calcium chelator complex. It is concluded that small amounts of these cations should be bound to the plasma membrane of bovine spermatozoa and inhibit the cellular calcium influx. 0.1 mM Cd2+ and NEM or 1mM diamide produced a calcium efflux from the spermatozoa together with an inhibition of cellular motility and an increase in glutamate-oxaloacetate transaminase release. Conversely the impermeant sulfhydryl reagent mersalyl caused a net calcium efflux but did not alter the cellular motility nor the transaminase release. It is suggested that the permeant thiol reagents could decrease the spermatozoal mobility by impairing the mitochondrial ATP-synthesis. © 1988.
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