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Physiol Rep 2019 Jun 01;711:e14029. doi: 10.14814/phy2.14029.
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Injection of mRNA isolated from trophozoites of Giardia intestinalis induces expression of three types of chloride currents in Xenopus laevis oocytes.

Ponce A , Ogazon Del Toro A , Jimenez L , Eligio-Garcia L , Jimenez-Cardoso E .

Giardia lamblia is one of the most important worldwide causes of intestinal infections, yet little is known about its cellular physiology, especially the diversity of ionic channels that this parasite expresses. In this work, we show that injection of mRNA isolated from trophozoites of Giardia, into Xenopus laevis oocytes, induces expression of three types of chloride currents (here referred to as ICl-G1, ICl-G2, and ICl-G3), which have different biophysical and pharmacological properties. ICl-G1 currents show inward rectification and voltage dependence are enhanced by hypotonicity, show a selectivity sequence of (I > Br > Cl > F), and are inhibited by NPPB, DIDS, SITS, 9AC, DPC, and Zinc. These findings suggest that ICl-G1 is the result of expression of chloride channels related to ClC2. ICl-G2 currents show outward rectification and are dependent of intracellular calcium, its selectivity sequence is (Cl > Br > I > F) and are inhibited by NPPB, DIDS, SITS, 9AC, DPC, niflumic acid, tannic acid, and benzbromarone. These findings suggest that they are produced by calcium dependent chloride channels (CaCC). The third type of currents (ICl-G3) appears only after a hypoosmotic challenge, and has similar properties to those described for ICl-swell, such as outward rectification, instant activation, and slow inactivation at large depolarizing voltages. They were blocked by NPPB, DIDS, 9AC, NIf, DCPIB, and tamoxifen. Our results indicate that Giardia intestinalis has at least three types of anion conductances.

PubMed ID: 31187589
PMC ID: PMC6560338
Article link: Physiol Rep

Species referenced: Xenopus laevis
Genes referenced: dtl nif nppb
GO keywords: chloride channel activity

Disease Ontology terms: giardiasis

Article Images: [+] show captions
References [+] :
Ackerman, Hypotonicity activates a native chloride current in Xenopus oocytes. 1994, Pubmed, Xenbase