Inhibition of Potassium Channels Affects the Ability of Pig Spermatozoa to Elicit Capacitation and Trigger the Acrosome Exocytosis Induced by Progesterone

Abstract

During capacitation, sperm undergo a myriad of changes, including remodeling of plasma membrane, modification of sperm motility and kinematic parameters, membrane hyperpolarization, increase in intracellular calcium levels, and tyrosine phosphorylation of certain sperm proteins. While potassium channels have been reported to be crucial for capacitation of mouse and human sperm, their role in pigs has not been investigated. With this purpose, sperm samples from 15 boars were incubated in capacitation medium for 300 min with quinine, a general blocker of potassium channels (including voltage-gated potassium channels, calcium-activated potassium channels, and tandem pore domain potassium channels), and paxilline (PAX), a specific inhibitor of calcium-activated potassium channels. In all samples, acrosome exocytosis was induced after 240 min of incubation with progesterone. Plasma membrane and acrosome integrity, membrane lipid disorder, intracellular calcium levels, mitochondrial membrane potential, and total and progressive sperm motility were evaluated after 0, 120, and 240 min of incubation, and after 5, 30, and 60 min of progesterone addition. Although blocking potassium channels with quinine and PAX prevented sperm to elicit in vitro capacitation by impairing motility and mitochondrial function, as well as reducing intracellular calcium levels, the extent of that inhibition was larger with quinine than with PAX. Therefore, while our data support that calcium-activated potassium channels are essential for sperm capacitation in pigs, they also suggest that other potassium channels, such as the voltage-gated, tandem pore domain, and mitochondrial ATP-regulated ones, are involved in that process. Thus, further research is needed to elucidate the specific functions of these channels and the mechanisms underlying its regulation during sperm capacitation.

Reproductive Consequences of Electrolyte Disturbances in Domestic Animals

“…Potassium channels are present in spermatogenic cells and the structures of mature spermatozoa. These channels are classified into voltage-gated potassium (Kv) channels, calcium-activated potassium (KCa) channels, internal rectifying potassium channels (Kir), and potassium channels in the tandem pore domain (K2P) [ 102 ]. They participate in the regulation of membrane potential and support sperm motility during the capacitation [ 103 ].…”

Investigate the interaction of testosterone/progesterone with ionic liquids on varying the anion to combat COVID‐19: Density functional theory calculations and molecular docking approach

“…[ 1 , 2 , 3 , 6 , 8 , 9 ] It is expected that this virus may interact with the sex hormones of humans like testosterone and progesterone, which play important role in regulation of different biological reactions in human beings like their growth, sexual activity, and others. [ 10 , 11 , 12 , 13 , 14 , 15 ] The solubility of testosterone and progesterone is not good; so to increase their solubility, ionic liquids (ILs) are being explored. Imidazolium, pyridinium, pyrrolidinium, piperidinium, ammonium bassed ILs are well investigated for different applications like green solvents, stabilization of biomolecules, extraction of compounds, and synthesis of nanomaterials and in the inhibition of the growth of the microorganisms.…”

Ion Channels of Spermatozoa: Structure, Function, and Regulation Mechanisms

“…The flux of calcium (Ca 2+ ) and bicarbonate (HCO 3 − ) across the sperm-plasma membrane has been extensively reported, due to the relevance of both ions as second messengers triggering sperm capacitation and hyperactivation in the female tract [ 1 ]. However, other ions such as potassium (K + ), sodium (Na + ), chloride (Cl − ) and hydrogen (H + ) are also relevant to male fertility, since they are implicated in the regulation of internal pH (pH i ) and/or the plasma membrane potential (Em) not only during sperm capacitation ( Figure 1 ) [ 2 , 3 , 4 ], but also throughout the spermiogenesis and epididymal maturation and upon ejaculation [ 4 , 5 ]. Most studies on ion channels are performed in mature sperm of mammalian species, specially from humans and rodents, and little data exist on their physiological role during germ cell differentiation and maturation.…”

“…Most of the original research included in this special issue focuses on the physiological role of K + and H + transporters in mammal sperm physiology. In these species, the sperm plasmalemma contains different K + transporters, such as voltage-gated potassium channels (K v ), inward-rectifier potassium channels (K ir ), calcium-activated potassium channels (K Ca ), and tandem-pore-domain potassium channels (KCNK) [ 3 , 5 , 9 ]. Poli et al [ 5 ] performed an excellent study on the expression and function of Kir4.1 and Kir5.1 channels in mature sperm cells from mice.…”

“…Interestingly, the deletion of Kir5.1 gene led to impaired sperm motility and fertility, but also reduced testicular development, thus highlighting the relevance of this channel in sperm-cell differentiation and function [ 5 ]. In their comprehensive research, Noto et al [ 3 ] analysed the relevance of K + transport across the plasma membrane during in vitro capacitation of pig sperm, by incubating sperm cells in the capacitation medium in either the presence or absence of a general blocker of K + channels or a specific blocker of Ca 2+ -activated K + (K Ca ) channels. The results obtained highlighted both the physiological relevance of K + transport to achieve the capacitated status of sperm cells and the close relationship between Ca 2+ and K + currents in capacitated sperm cells.…”