Echeverry, Fabio Andrés: Physiological role of cation channels of P. irradians ciliary photoreceptors and human sperm. - Bonn, 2017. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
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author = {{Fabio Andrés Echeverry}},
title = {Physiological role of cation channels of P. irradians ciliary photoreceptors and human sperm},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2017,
month = apr,

volume = 00024,
note = {Eukaryotic flagella and cilia are antenna-like cellular extrusions, shaped by microtubules and covered by a specialized extension of the plasma membrane. They serve several tasks, like light and olfactory sensation or cell motility and are, therefore, present in various cell types. To exert their function flagella and cilia use a specific set of ion channels and signaling molecules. I investigated the function of different ion channels in the physiology of ciliary photoreceptors of the bay scallop (P. irradians) and the flagellum of human sperm.
Light stimulation of P. irradians ciliary photoreceptors induces a hyperpolarization of the cell membrane, presumably mediated by the opening of cGMP-dependent K+ selective channels. This stands in contrast to the well characterized light response of vertebrate rod and cone photoreceptors, where light stimulation induces a closure of cGMP-gated non-selective cation channels. I provided evidence that ERG, HCN and CNG channels are expressed in ciliary photoreceptors of P. irradians. Furthermore, I used caged cGMP and the patch-clamp technique to investigate ERG, HCN and CNG channels of ciliary photoreceptors of P. irradians.
Like photoreceptors, the physiology of sperm flagella is based on the fine interplay of several ion channels. The intracellular Ca2+ concentration has been shown to orchestrate various sperm functions like the swimming behavior and the acrosome reaction. In human and mouse sperm, Ca2+ entry is mediated by the principal Ca2+ channel of sperm (CatSper), which is modulated by the intracellular pH and membrane voltage (Vm). In mouse sperm, Vm is predominantly controlled by the K+ channel Slo3. In contrast, the identity of the principal K+ channel of human sperm remains elusive. By patch-clamp recordings, I investigated the K+ currents mediated by human Slo3 (hSlo3) heterologously expressed in CHO cells and compared them to the K+ currents of human sperm (IKsper). My work showed striking similarities between hSlo3 carried-currents and human IKsper. I showed that hSlo3 currents are: activated by Ca2+, weakly enhanced by intracellular alkalization, and inhibited by progesterone in the micromolar range, which are properties remarkably similar to IKsper of human sperm.},

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