It is well known that insemination of cryopreserved semen always results in lower fertility when compared to fresh semen; on the other hand there is an increased interest and demand for frozen equine semen by the major breeder associations because of the utility arising from semen already "on hand" at breeding time. In this paper, we demonstrated that equine sperm cells express L-type voltage gated calcium channels; their localization is restricted to sperm neck and to the principal piece of the tail both in fresh and frozen-thawed spermatozoa. We also studied, at the membrane level, the causes of cryoinjury focusing on the function of L-calcium channels. We demonstrated that in cryopreserved spermatozoa the mean basal value of [Ca2+]i is higher than that of spermatozoa from fresh semen (447.130 nM vs 288.3 nM, P<0.001) and that L-type channels function differently in response to their agonist/antagonist in relation to semen condition (fresh or frozen-thawed). We found that upon agonist addition to the culture medium, the [Ca2+]i increase was higher in frozen than in fresh semen (Δ[Ca2+]i=124.59 nM vs 16.04 nM; P<0.001) while after the antagonist addition the [Ca2+]i decrease was lower in frozen than in fresh semen (Δ[Ca2+]i=32.5 nM vs 82.5 nM; P<0.001). In this paper we also discuss the impact of cryopreservation on sperm physiology.
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|Titolo:||Localization and functional modification of L-type voltagegated calcium channels in equine spermatozoa from fresh and frozen semen|
|Data di pubblicazione:||2015|
|Appare nelle tipologie:||1.1 Articolo in rivista|