ATP Content and Adenine Nucleotide Catabolism in African Catfish Spermatozoa Stored in Various Energetic Substrates

Abstract

Influence of various energetic substrates on ATP content and adenine nucleotide catabolism in African catfish, Clarias gariepinus spermatozoa was investigated. Present data indicate that sperm storage at 4°C in the presence of different energetic substrates leads to time dependent ATP depletion. Among the substrates studied (i.e. glycine, glucose, or lactate plus pyruvate), the lactate plus pyruvate seems to be the most favourable substrate to maintain ATP concentration. ATP depletion is associated with increase of the AMP content, while ADP concentration is changing only slightly. Moreover, significant increase in hypoxanthine content both in the sperm and a storage medium was found. Adenine nucleotide energy charge (AEC) decreased significantly during the first 24 h when sperm was stored in the presence of glycine. During the same period, only slight decrease in AEC was observed in spermatozoa stored in the presence of glucose and no significant changes were found in the presence of lactate plus pyruvate. A further decrease in AEC was observed until 120 h of storage in the medium containing glycine, lactate plus pyruvate or glucose. However, the changes were relatively small when spermatozoa were stored in the presence of lactate plus pyruvate. Important finding is that in contrast to the results reported recently, AEC value in fresh milt (at 0 time of storage) was in the normal range. The present study shows that African catfish spermatozoa are able to maintain physiological level of ATP and AEC when they are stored in the presence of favourable energetic substrates. In conclusion, the results of this investigation suggest that successful short-term storage of African catfish milt depends on energetic substrates supply.Abbreviations: AEC -adenine nucleotide energy charge; ADP -adenosine diphosphate; AMP -adenosine monophosphate; ATP -adenosine triphosphate; cAMP -cyclic AMP; HPLC -high performance liquid chromatography; IMP -inosine monophosphate; TAN -total adenine nucleotide.

Bioenergetics of fish spermatozoa during semen storage

“…When fresh catfish semen was kept in the extender for 24 h, the concentration of ATP and the AEC decreased, whereas the concentration of AMP increased significantly (Table 2). No significant changes were observed in the others parameters studied, including creatine phosphate, creatine, ADP and TAN levels ( Table 2; Ziętara et al 2004b). Interestingly, a significant increase in AMP concentration was not associated with significant changes in ADP concentration (Table 2; Ziętara et al 2004b).…”

“…No significant changes were observed in the others parameters studied, including creatine phosphate, creatine, ADP and TAN levels ( Table 2; Ziętara et al 2004b). Interestingly, a significant increase in AMP concentration was not associated with significant changes in ADP concentration (Table 2; Ziętara et al 2004b). The reason for a stable ADP concentration in catfish spermatozoa is currently not clear.…”

“…Many studies have confirmed that the physiological AEC of somatic cells and spermatozoa ranges from 0.8 to 0.95 (Atkinson 1977;Dreanno et al 1999b;Rurangwa et al 2001;Smolenski et al 1990;Ziętara et al 2004b). Dreanno et al (1999b) demonstrated that after activation of turbot (Psetta maxima) spermatozoa, the intracellular ATP concentration decreased rapidly and ADP and AMP concentrations increased; simultaneously, the AEC value declined from 0.95 before motility initiation to about 0.5 after 60 s of spermatozoa movement.…”

“…In contrast, the AEC value of carp (Cyprinus carpio) spermatozoa kept under identical conditions was 0.96 (Rurangwa et al 2001(Rurangwa et al , 2002. However, when freshly isolated catfish semen was used, and the procedure for adenine nucleotide extraction was as fast as possible, catfish spermatozoa displayed essentially the same AEC values as carp spermatozoa (Ziętara et al 2004b). It is therefore likely that the surprisingly low AEC in catfish spermatozoa resulted from a more rapid degradation of adenine nucleotide during semen preparation for adenine nucleotide determination, leading to the conclusion that catfish spermatozoa, in contrast to carp spermatozoa, have a lower capacity to maintain intracellular ATP concentration.…”

“…When energetic substrates (glucose or lactate) were added to the storage medium, the ATP concentration increased to the control values (Table 2); however, the differences in the mean ATP concentration observed in the presence of glucose and Values are the mean ± SD (n = 6) * P \ 0.05 versus fresh semen (0 h in extender), ** P \ 0.001 versus fresh semen (0 h in extender), *** P \ 0.01 versus fresh semen (0 h in extender). No significant changes in other parameters included in the table were found a Adenylates from spermatozoa were extracted and analysed by HPLC as described by Ziętara et al (2004b) b Extender composition: see footnote to Table 1 Fish Physiol Biochem (2009) 35:607-614 609 lactate did not reach statistical significant levels after 24 h of semen storage ( Table 2). The increase in ATP occurred concomitantly with a decrease in AMP concentration both in the presence of glucose or lactate (Table 2).…”