Regulation of sperm motility by cell-signalling events in human sperm

Achikanu, Cosmas Ezekaibeya (2017). Regulation of sperm motility by cell-signalling events in human sperm. University of Birmingham. Ph.D.

[img] Achikanu17PhD.pdf
PDF - Accepted Version
Restricted to Repository staff only until 1 December 2020.

Download (2MB)


Ca\(^{2+}\) signals from activated Ca\(^{2+}\) channels (CatSper) and mobilisation of Ca\(^{2+}\) stores regulate human sperm cell behaviour as they ascend the female tract. I investigated the effects on human sperm [Ca\(^{2+}\)]i and behaviour of CatSper channel activation (alkaline pH and progesterone) and Ca2+-store mobilisation (4-aminopyridine, thimerosal) using a fluorescence plate reader and CASA. Extracellular alkalinisation raised pH¬i (pHi = 6.9 and 7.2 at pHo7.4 and 8.5 respectively), caused tonic elevation of [Ca\(^{2+}\)]i, which was partially inhibited by CatSper block and increased the proportion of hyperactivated cells (from 1.8±0.5 to 10.5±1.6%; n=34, P=1x10\(^{-7}\)). Progesterone elevated [Ca\(^{2+}\)]i but caused negligible hyperactivation. Co-application of these stimuli revealed little, if any, synergistic interaction. Ca\(^{2+}\)-store mobilisation (4-aminopyridine) caused prolonged [Ca\(^{2+}\)]i elevation and was associated with strong hyperactivation. Analysis of [Ca\(^{2+}\)]i and hyperactivation data from 24 different conditions in this study showed a continuous relationship between [Ca\(^{2+}\)]i and hyperactivation. The strong hyperactivating effect of store mobilisation (compared to CatSper activation) may reflect opening of store-operated channels. Human sperm behaviour assessed over a 180 s recording revealed regular ‘switching’ between progressive and various hyperactivated types. Mobilisation of Ca\(^{2+}\) stores potently increased hyperactivated behaviour and suppressed the rate of behavioural switching.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
College/Faculty: Colleges (2008 onwards) > College of Life & Environmental Sciences
School or Department: School of Biosciences
Funders: Other
Other Funders: Federal Government Of Nigeria
Subjects: Q Science > QH Natural history > QH301 Biology


Request a Correction Request a Correction
View Item View Item


Downloads per month over past year