Characterization of cyclic adenine dinucleotide phosphate ribose levels in human spermatozoa.
OBJECTIVE
To determine the presence of the Ca2+-releasing pyridine nucleotide derivative, cyclic adenine dinucleotide phosphate ribose (cADPR), in human spermatozoa and to investigate its role in progesterone-induced Ca2+ oscillations in spermatozoa.


METHODS
Biochemical investigation on human spermatozoa from healthy volunteers.


METHODS
Healthy volunteers in an academic research environment.


METHODS
Ten volunteers.


METHODS
None.


METHODS
The cADPR levels.


RESULTS
Human spermatozoa contain micromolar concentrations of cADPR that do not change significantly during sperm capacitation. An active synthetic machinery for cADPR is present in human spermatozoa, whereas degradation activity is minimal. Although progesterone-induced Ca2+ oscillations are dependent on the ryanodine receptor, they are unaffected by cADPR antagonists.


CONCLUSIONS
It appears that cADPR does not to play a role in Ca2+ oscillations in spermatozoa, but the presence of high concentrations of cADPR suggests that, instead, it may be introduced into the egg at fertilization and play a role in the Ca2+ transient immediately following sperm-egg fusion.
Billington
Richard A
RA
DiSCAFF, Universita' del Piemonte Orientale, Novara, Italy.
Harper
Claire
C
Bellomo
Elisa A
EA
Publicover
Steve
S
Barratt
Christopher L R
CL
Genazzani
Armando A
AA
D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002478:Cells, Cultured; D036563:Cyclic ADP-Ribose / Q000378:metabolism*; D006801:Humans; D008297:Male; D013075:Sperm Capacitation / Q000502:physiology*; D013094:Spermatozoa / Q000378:metabolism*
D036563:Cyclic ADP-Ribose; D002118:Calcium