Cryopreservation alters the Ca²⁺ flux of bovine spermatozoa

Abstract

. 1994. Cryopreservation alters the Ca2* flux of bovine spermatozoa. Can. J. Anim. Sci. 74: 45-51. Capacitation and the acrosome reaction are Ca2*-dependent events that must be properly timed for successful fertilization to occur. To test the hypothesis that the cryopreservation procedures alter the ability ofbovine spermatozoa to regulate Ca'-, the ability of Percoll-washed fresh and cryopreserved spermatozoa obtained from the same ejaculate (four ejaculates from each of six bulls) to regulate Ca" over time was monitored using the fluorescent Ca'' chelator indo-1. The ability of spermatozoa to control Ca'* levels varied among ejaculates from a bull, and among bulls; these effects were statistically accounted for in the analysis of the effects of cryopreservation. Initially, cryopreserved spermatozoa had lower viability, motility, and normal acrosome scores and more intra-and extra-cellular Ca'-than fresh spermatozoa. Intra-and extra-cellular Ca'-was monitored for,150 min, with I mM exogenous Ca2* or buffer being added at 30 min to the spermatozoa being used to monitor intracellular Ca2*. By 30 min, extracelirilar Ca2* was higher for fiesh cells and then remained constant. Intracellular Ca2* of fresh and cryopresewed spermatozoa in Ca2*-free media"slowly increased. While both fresh and cryopreserved cells in Ca2*-supplemented media accumulated Ca2* more rapidly, cryopreserved spermatozoa did so faster than fresh. Post-experimental viability was lower in cryopreserved spermatozoa that had been exposed to exogenous Ca'*. In conclusion, cryopreservation affects initial intraand extia-cellular Ca2* levels of bovine spermitozoa, and iheir ability to control subsequent rates of Ca2* accumulation.

Effect of cholesterol-loaded-cyclodextrin on sperm viability and acrosome reaction in boar semen cryopreservation

“…Sperm capacitation can induce cholesterol efflux from the sperm membrane (Choi and Toyoda, 1998;Cross, 1999;Iborra et al, 2000;Parinaud et al, 2000;Visconti et al, 1999). Similarly, when sperm are cooled or frozen, the membranes undergo a phase transition, which results in rearrangement of membrane lipids and proteins (Hammerstedt et al, 1990;Parks and Graham, 1992) and a loss of lipids from the membranes (DarinBennett et al, 1973), which in turn causes protein and lipid aggregation within the membrane, and a loss of membrane-selective permeability (Bailey and Buhr, 1994;Buhr et al, 1989), resulting in sperm that are prematurely capacitated (Cormier et al, 1997;Parrish et al, 1986). This premature capacitation could reduce fertilizing ability and lifespan of the sperm (Cormier et al, 1997;Parrish et al, 1986).…”

Vitrification Technique - New Possibilities for Male Gamete Low-Temperature Storage

“…The permeability of these channels is increased on cooling, affecting calcium regulation (Robertson & Watson, 1986;Robertson et al, 1988). These facts have serious consequences for cell function (Bailey & Bhur, 1994) and many changes may be incompatible with sperm viability. In this case we have decided to apply to dog spermatozoa the early developed us vitrification protocol (Isachenko et al, 2008) for human sperm cells.…”

Variations of protein profiles and calcium and phospholipase A2 concentrations in thawed bovine semen and their relation to acrosome reaction

“…Calcium has a fundamental role in acrosome capacitation and reaction (Yanagimachi, 1988). Calcium flux control through the spermatozoal membrane is essential to fertilization (Bailey and Buhr, 1993). The complementary nature of spermatozoon zona-pellucida receptors linked to ZP3 glycoprotein is not well known, e.g., ZP3 may interact and/or activate a particular sperm binding protein/receptor to permit spermatozoon binding, subsequently inducing production of intracellular second messengers leading to acrosome reaction.…”