Steven Reynolds1, Sarah Calvert2, Jack Pearson2, Allan Pacey2, and Martyn Paley1
1Academic unit of radiology, University of Sheffield, Sheffield, United Kingdom, 2Academic Unit of Reproductive and Developmental Medicine, University of Sheffield, Sheffield, United Kingdom
Two main metabolic pathways provide energy for sperm swimming; glycolysis
and oxidative phosphorylation, producing different biomarkers, including
lactate (glycolysis) and bicarbonate/CO2 (Oxphos) that can be
detected by MR spectroscopy. By incubating 13C labeled exogenous metabolites
with human spermatozoa we identify metabolic pathways and quantify rates of
metabolism in spermatozoa. The rate constants for glucose and pyruvate
conversion to lactate were estimated as 1.1±0.5x10-6s-1
and 2.4±1.1x10-6s-1 per million sperm respectively
(mean±SD, n=4). Metabolic
pathways used by live sperm were assessed and work is being done to estimate the relative
importance of different metabolic activity in sperm of normozoospermic and
asthenozoospermic patients.
