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Native ion current coupled to purinergic activation via basal and mechanically induced ATP release in xenopus follicles
Author(s) -
Saldaña Carlos,
Garay Edith,
Rangel Gisela Edith,
Reyes Luis Manuel,
Arellano Rogelio O.
Publication year - 2009
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.21611
Subject(s) - purinergic receptor , xenopus , oocyte , apyrase , microbiology and biotechnology , stimulation , extracellular , chemistry , follicular cell , paracrine signalling , medicine , endocrinology , biophysics , biology , receptor , biochemistry , follicular phase , embryo , gene
Xenopus follicle‐enclosed oocytes are endowed with purinergic receptors located in the follicular cell membrane; their stimulation by ATP elicits an electrical response that includes generation of a fast inward current ( F Cl ) carried by Cl − . Here, it was found that mechanical stimulation of the follicle provoked a native electrical response named I mec . This was dependent on coupling between oocyte and follicular cells, because I mec was eliminated by enzymatic defolliculation or application of uncoupling drugs, such as heptanol or carbenoxolone. Moreover, the characteristics of I mec suggested that it corresponded with opening of the Cl − channel involved in F Cl . For example, I mec showed cross‐talk with the membrane mechanism that activates the F Cl response and anionic selectivity similar to that displayed by F Cl . Also like F Cl , I mec was independent of extracellular or intracellular Ca 2+ . Furthermore, I mec was inhibited by superfusion with a purinergic antagonist, suramin, or by an enzyme that rapidly hydrolyzes ATP, apyrase. The response to mechanical stimulation was reconstituted in defolliculated oocytes expressing P2X channels as an ATP sensor. Recently, it has been shown that ATP release from the Xenopus oocyte is triggered by mechanical stimulation. Together, these observations seemed to indicate that I mec is activated through a mechanism that involves oocyte release of ATP that diffuses and activates purinergic receptors in follicular cells, with subsequent opening of F Cl channels. Thus, I mec generation disclosed a paracrine communication system via ATP between the oocyte and its companion follicular cells that might be of physiological importance during the growth and development of the gamete. J. Cell. Physiol. 218: 355–365, 2009. © 2008 Wiley‐Liss, Inc.