Emerging Concepts in Ion Channel Biophysics

Emerging Concepts in Ion Channel Biophysics

Poster Abstracts

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.

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