Hamster oocyte membrane potential and ion permeability vary with preantral cumulus cell attachment and developmental stage
Tóm tắt
In vitro maturation of mammalian oocytes is an area of great interest due to its potential application in the treatment of infertility. The morphological and physiological changes that occur during oocyte development are poorly understood, and further studies are needed investigating the physiological changes associated with oocyte maturation. In this study we evaluated the membrane potential and the sodium/potassium permeability ratio of oocytes acutely isolated, and cumulus-oocyte complexes in metaphase II and preantral follicle stages. Intracellular electrical recordings revealed that cumulus-enclosed oocytes have a membrane potential significantly more negative at the preantral follicle stage than at metaphase II stage (-38.4 versus -19.7 mV, p < 0.0005). The membrane potential of the cumulus-free oocytes was not different between the preantral and metaphase II stages. The membrane potential of the cumulus cells forming preantral stage follicles was shown to be significantly different from that of the oocyte within the follicle (-28.6 versus -38.4 mV, p < 0.05). The sodium/potassium permeability measured in cumulus-enclosed oocytes at the preantral stage equaled a mean value of 0.33. The ratio was significantly lower when measured in oocytes denuded of cumulus cells or cumulus-enclosed metaphase II oocytes, 0.76, 0.79, 0.77 respectively (p < 0.001). These data show a change in the membrane potential and Na+/K+ permeability ratio during ooycte development from the preantral stage oocyte to the metaphase II stage. We have also demonstrated a change in the preantral oocyte membrane potential when surrounding cumulus cells are removed; either due to membrane changes or loss of cumulus cells.
Tài liệu tham khảo
Wright CS, Becker DL, Lin JS, Warner AE, Hadry K: Stage-specific and differential expression of gap junctions in the mouse ovary: connexin-specific roles in follicular regulation. Reprod. 2001, 121(1): 77-88.
Kol S, Adashi EY: Intraovarian factors regulating ovarian function. Curr. Opin. Obstet. Gynecol. 1995, 7(3): 209-213.
Zeilmaker GH, Vermeiden JP, Verhamme CM, Van Vliet AC: Observations on rat and mouse oocyte maturation in vivo and in vitro: morphology and physiology. Eur. J. Obstet. Gynecol. Reprod. Biol. 1974, 4(1): 15-24.
Okamoto H, Takahashi K, Yamashita N: Ionic currents through the membrane of the mammalian oocyte and their comparison with those in the tunicate and sea urchin. J. Physiol. 1977, 267: 465-495.
Canipari R: Oocyte-granulosa cell interactions. Hum. Reprod. Update. 2000, 6(3): 279-289.
Mattioli M, Barboni B, Bacci ML, Seren E: Maturation of pig oocytes: observations on membrane potential. Biol. Reprod. 1990, 43: 318-322.
Downs SM: The influence of glucose, cumulus cells, and metabolic coupling on ATP levels and meiotic control in the isolated mouse oocyte. Devlop. Biol. 1995, 167: 502-512. 10.1006/dbio.1995.1044.
McCullough DH, Levitan H: Rabbit oocyte maturation: changes of membrane resistance, capacitance, and the frequency of spontaneous transient depolarizations. Develop. Biol. 1987, 120: 162-169.
Racowsky C, Satterlie RA: Decreases in hetreologus metabolic and dye coupling, but not in electrical coupling, accompany meiotic resumption in hamster oocyte-cumulus complexes. Euro. J. Cell. Biol. 1987, 43: 283-292.
Racowsky C, Satterlie RA: Metabolic, fluorescent dye and electrical coupling between hamster oocytes and cumulus cells during meiotic maturation in vivo and in vitro. Devel. Biol. 1985, 108: 191-202.
Wert SE, Larsen WJ: Meiotic resumption and gap junction modulation in the cultured rat cumulus-oocyte complex. Gamete Res. 1989, 22: 143-162.
Gilula NB, Epstein ML, Beers WH: Cell-to-cell communication and ovulation. A study of the cumulus-oocyte complex. J. Cell Biol. 1978, 78: 58-75.
Suzuki H, Jeong S-B, Yang X: Dynamic changed of cumulus-oocyte cell communication during in vitro maturation of porcine oocytes. Biol. Reprod. 2000, 63: 723-729.
Greenfield LJ, Hackett JT, Linden J: Xenopus oocyte K+ current. III. Phorbol esters and pH regulate current at gap junctions. Am. J. Physiol. 1990, 259 (Cell Physiol. 28): C792-C800.
Roy SK, Greenwald GS: An enzymatic method for dissociation of intact follicles from the hamster ovary: histological and quantitative aspects. Biol. Reprod. 1985, 32: 203-215.
Brown HM, Saunders JH: Cation and anion sequences in dark-adapted Balanus photoreceptor. J. Gen. Physiol. 1977, 70: 531-543.
Mullins LJ, Noda K: The influence of sodium-free solutions on the membrane potential of frog muscle fibers. J. Gen. Physiol. 1963, 43: 117-132.