The activating effect of bicarbonate on sperm motility and respiration at ejaculation

Biochimica et Biophysica Acta (Impact Factor: 4.66). 07/1987; 924(3):519-29. DOI: 10.1016/0304-4165(87)90168-1
Source: PubMed


Mature porcine sperm preserved in the cauda epididymis are quiescent. At ejaculation, they are mixed with the seminal vesicle fluid containing HCO3- and are rapidly activated. The role of HCO3- on the sperm activation process at ejaculation was studied in vitro. HCO3- quickly increased the motility, respiration rate and cAMP content of the porcine epididymal sperm. The extent of activation was proportional to the pCO2 in the medium. The activating effect of HCO3- on the motility was observed even in the absence of fructose as well as in the presence of KCN. 8-Bromoadenosine 3',5'-cyclic monophosphate and theophylline showed similar activating effects to that of HCO3-. However, HCO3(-)-free seminal plasma, Ca2+, amino acids, intermediates of the Krebs cycle, substrates of respiration and increases in the intracellular pH, extracellular pH or ionic strength of the medium had no effect. Fructose sustained the active state of the sperm and gradually increased both the motility and respiration rate when the dose of HCO3- was low. The anion channel blocker enhanced the activating effect of HCO3-. These results suggest that, upon ejaculation, HCO3- is a unique activator in vivo which makes the quiescent sperm motile via the HCO3(-)-adenylate cyclase-cAMP system, to which an endogenous HCO3- derived from metabolic CO2 may be related.

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    • "It has been known for more than sixty years that the luminal fluid of the female reproductive tract has a HCO 3 À content two to four times higher than that of the plasma (Vishwakarma, 1962; Murdoch and White, 1968; Maas et al., 1977). It is also known that HCO 3 À is essential to a number of reproductive events occurring in the female reproductive tract (Chan et al., 2006, 2009, 2012; Liu et al., 2012), including sperm motility (Mann and Lutwak-Mann, 1982; Tajima et al., 1987; Jones and Murdoch, 1996; Abaigar et al., 1999; Holt and Harrison, 2002; Wennemuth et al., 2003; Wennemuth, 2004; Mannowetz et al., 2011), capacitation (Boatman and Robbins, 1991; Shi and Roldan, 1995; Zhou et al., 2005), a sperm activation process by which sperm acquire their ability to fertilise the egg, and early embryo development (Chen et al., 2010; Lu et al., 2012). The questions as to how HCO 3 À is secreted into the lumen of the female reproductive tract and how HCO 3 À is transported into sperm and embryo have not been fully addressed. "
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    ABSTRACT: The solute carrier 26 (SLC26) family emerges as a distinct class of anion transporters with its members SLC26A3 (Slc26a3) and SLC26A6 (Slc26a6) reported to be electrogenic Cl(-) /HCO3 (-) exchangers. While it is known that uterine fluid has high HCO3 (-) content and that HCO3 (-) is essential for sperm capacitation, the molecular mechanisms underlying the transport of HCO3 (-) across uterine epithelial cells and sperm have not been fully investigated. The present review re-examines the results from early reports studying anion transport, finding clues for the involvement of Cl(-) /HCO3 (-) anion exchanges in electrogenic HCO3 (-) transport across endometrial epithelium. We also summarize recent work on Slc26a3 and Slc26a6 in uterine epithelial cells and sperm, revealing their functional role in working closely with the cystic fibrosis transmembrane conductance regulator (CFTR) for HCO3 (-) transport in these cells. The possible involvement of these anion exchangers in other HCO3 (-) dependent reproductive processes and their implications for infertility are also discussed.
    Cell Biology International 01/2014; 38(1). DOI:10.1002/cbin.10183 · 1.93 Impact Factor
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    • "During the epididymal maturation process in vivo, cyclic phosphodiesterase level of goat sperm decreases sharply [Jaiswal and Majumder, 1996] showing thereby that the sperm motility induction is associated with downregulation of cyclic phosphodiesterase activity resulting in decrease of the breakdown of cyclic-AMP which is essential for sperm forward motility [Jaiswal and Majumder, 1998; Okamura et al., 1985; Tajima et al., 1987; Rojas et al., 1992; Garbers and Kopf, 1980; Yeung , 1984; Vijayraghavan et al., 1985]. It is still not clear as to how the FMSF-receptor interaction triggers the flagellar motility. "
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    ABSTRACT: Spermatozoa are highly specialised cells that possess flagellar motility which is essential for natural fertilization. Sperm motility measurement is associated with a serious technical problem due to sticking of these cells to the glass surface of haemocytometer required for motility analysis. Our research work has led to the discovery of novel anti-sticking factors (ASF-I and II) in caprine epididymal plasma (EP) that showed high affinity for inhibiting adhesion of spermatozoa to glass. These factors have been purified to apparent homogeneity by using multiple biochemical fractionation procedures. ASF-I and II are 47 and 36 kDa, heat-stable glycoproteins. The purified ASFs are suitable for eliminating the “cell-sticking" artefact in motility assays, as they have no role in sperm motility. Using ASFs in routine sperm motility assays, we have investigated biochemical basis of caprine sperm forward progression. A motility-promoting protein (FMSF) has been purified from buffalo serum using CM-cellulose chromatography, HPLC and native polyacrylamide gel electrophoresis. FMSF is a 66 kDa specific monomeric protein. Recently MIP: a motility initiating protein has been purified from EP. It is a 125 kDa dimeric protein made up of two subunits: 70 and 54 kDa. FMSF is also present in EP. Both the proteins serve as the physiological activators of sperm motility.
    Protein Purification, Edited by Miguel Benitez and Victoria Aguiree, 02/2012: chapter 01: pages 1-90; Nova Science Publishers, Inc.., ISBN: 978-1-61470-098-2
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    • "Of note, the expression of SLC26A3 in the human prostate has been reported [50] and we have also detected SLC26A6 in rat prostate (Xie C unpublished data), both of which are known to be able to transport HCO3− across the apical membrane of many epithelia [51] and work in concert with CFTR. The CFTR-mediated prostatic HCO3− secretion may be important for sperm motility upon ejaculation since prostate secretion is known to contribute to the semen volume and HCO3− is the key factor triggering sperm motility [52], [53]. The physiological role of the CFTR-mediated HCO3− secretion under normal condition warrants further studies. "
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    ABSTRACT: Prostatitis is associated with a characteristic increase in prostatic fluid pH; however, the underlying mechanism and its physiological significance have not been elucidated. In this study a primary culture of rat prostatic epithelial cells and a rat prostatitis model were used. Here we reported the involvement of CFTR, a cAMP-activated anion channel conducting both Cl(-) and HCO(3)(-), in mediating prostate HCO(3)(-) secretion and its possible role in bacterial killing. Upon Escherichia coli (E. coli)-LPS challenge, the expression of CFTR and carbonic anhydrase II (CA II), along with several pro-inflammatory cytokines was up-regulated in the primary culture of rat prostate epithelial cells. Inhibiting CFTR function in vitro or in vivo resulted in reduced bacterial killing by prostate epithelial cells or the prostate. High HCO(3)(-) content (>50 mM), rather than alkaline pH, was found to be responsible for bacterial killing. The direct action of HCO(3)(-) on bacterial killing was confirmed by its ability to increase cAMP production and suppress bacterial initiation factors in E. coli. The relevance of the CFTR-mediated HCO(3)(-) secretion in humans was demonstrated by the upregulated expression of CFTR and CAII in human prostatitis tissues. The CFTR and its mediated HCO(3)(-) secretion may be up-regulated in prostatitis as a host defense mechanism.
    PLoS ONE 12/2010; 5(12):e15255. DOI:10.1371/journal.pone.0015255 · 3.23 Impact Factor
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