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Emerging Concepts in Ion Channel Biophysics
Poster Abstracts
94
12-POS
Board 12
The Effect of Arachidonic Acid (AA) on T-type Ca
2+
Currents in Mouse Spermatogenic
Cells
Olga Bondarenko
, Ignacio López-González, Alberto Darszon.
Instituto de Biotecnología, UNAM, Cuernavaca, Morelos, Mexico.
Mouse spermatogenic cells express T-type Ca
2+
currents (I
CaT
), which are encoded by Ca
V
3.1
and Ca
V
3.2 genes and could play a relevant role in the spontaneous Ca
2+
oscillations during
spermatogenesis. However, the mechanism by which T-type channel currents are regulated
during spermatogenesis is still unclear. A previous report documented the presence of the α/β
hydrolase domain-containing protein 2 in the male germ line, which can be activated by different
hormones and produces arachidonic acid (AA) and glycerol from 2-arachinoylglicerol. In this
study we investigated the potential regulation of spermatogenic cell T-type Ca
2+
currents by AA.
To this effect we recorded I
CaT
in whole cell electrophysiological recordings in spermatogenic
cells in the absence or presence of different AA concentrations. AA inhibits I
CaT
in a dose-
dependent manner, with an IC
50
=186 nM without shifting the I-V curve. I
CaT
lacks run down in
control conditions and AA-induced I
CaT
inhibition was reached 5 minutes after addition and was
stable through time. The I
CaT
inhibition by external AA was reverted pre-incubating this
compound in presence of albumin (BSA, 1%), suggesting AA incorporates into the
spermatogenic cell plasma membrane. Consistently, longer incubation of spermatogenic cells
with different AA concentrations reduces the BSA potency to revert the AA-induced I
CaT
inhibition, possibly indicating a higher incorporation of AA into the spermatogenic cell plasma
membrane. Finally, preliminary results show AA does not modify the time to peak or the
inactivation kinetics of the I
CaT
suggesting a reduction of the available Ca
2+
channel fraction as
the inhibitory mechanism of I
CaT
.
Acknowledgements: OB is a fellow from DGAPA-UNAM (Mexico). This work was supported
by CONACyT Fronteras 71 to AD; PAPIIT/UNAM: IN205516 to AD, and IN204914 to ILG;
NIH RO1 HD038082-13 to AD.