Acetylcholine receptors in the oocyte membrane

Kusano, Kazuo; Miledi, Ricardo; Stinnakre, Jacques

doi:10.1038/270739a0

Cited by 183 publications

(129 citation statements)

References 5 publications

Supporting

Mentioning

125

Contrasting

Order By: Relevance

“…The membrane potential of Xenopus oocytes that have been dissected from their follicles is known to be between -30 and -70 mV (25,26). Kusano et al (26) have recently shown that acetylcholine produces a depolarization in the Xenopus membrane potential, and they concluded that this was due to the opening of chloride channels.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Electrical currents through full-grown and maturing Xenopus oocytes.

Robinson¹

1979

Proc. Natl. Acad. Sci. U.S.A.

108

View full text Add to dashboard Cite

An extracellular vibrating electrode was used to map the current pattern around Xenopus laevis oocytes. Current was found to enter the animal hemisphere and leave the vegetal hemisphere; in fully grown oocytes from which the follicle cells had been removed, the maximal current density was about 1 uA/cm2. This current decreased to nearly zero in response to progesterone and several other maturation-producing agents. In the case of progesterone, the decline began within a few minutes of the addition of the hormone and proceeded with a half-time of about 20 min.An analysis of the effects on the current of the removal or addition of various ions and drugs led to the inference that the major current-carrying ion was chloride and that the chloride permeability was controlled by calcium. An ubiquitous feature of nonmammalian animal eggs is the presence of an animal-vegetal axis. The nucleus of the egg is generally displaced toward the animal pole and this pole is the site of polar body formation. In many amphibian eggs, the axis is readily distinguished by the pigment accumulation at the animal pole and the yolk mass at the vegetal pole. Superimposed on this visible polarity is a developmental polarity: the animal pole gives rise to the ectodermal parts of the embryo and the vegetal pole, to the endodermal. (For a recent review, see refs. 1 and 2.) When the full-grown anuran oocyte is exposed to progesterone, a sequence of events is triggered, leading to the reinitiation of meiosis and formation of a fertilizable egg. This process is also a polar one. The basal portion of the germinal vesicle is the first to break down as the entire germinal vesicle moves toward the animal pole (3).Our knowledge of the physical forces that might produce such asymmetries and direct polar movements remains limited. The oocytes are randomly oriented in the ovary; thus gravity is not the causal agent. Strong evidence has now accumulated in the case of fucoid algae eggs that electrical currents and ion gradients are involved in transducing environmental asymmetries into cellular polarity (4-6). Electrical currents associated with growth and localization processes have also been shown to exist in insect oocytes (7), pollen tubes (8), and regenerating Acetabularia (9). There are also a few older surface potential measurements from which the existence of polar currents in animal eggs can be inferred (10). It is against this background that this investigation of animal-vegetal currents in Xenopus oocytes and eggs was begun.METHODS AND MATERIALS Sexually mature Xenopus laevls females were obtained from the South African Snake Farm, Fish Hoek, South Africa. To obtain oocytes, females were anesthetized by chilling in an ice bath, portions of their ovaries were removed, and the oocytes were then manually dissected from their follicles. In some cases, the remaining follicle cells were removed by a 5-min treatment with Pronase (50 ;tg per ml in Steinberg's solution).A vibrating platinum electrode was used to measure extracellular currents. T...

show abstract

Section: Resultsmentioning

confidence: 99%

“…Kusano et al (26) have recently shown that acetylcholine produces a depolarization in the Xenopus membrane potential, and they concluded that this was due to the opening of chloride channels. The reversal potential for this effect was -25 mV which would put the internal chloride concentration at about 40 mM.…”

Section: Resultsmentioning

confidence: 99%

Electrical currents through full-grown and maturing Xenopus oocytes.

Robinson¹

1979

Proc. Natl. Acad. Sci. U.S.A.

108

View full text Add to dashboard Cite

show abstract

“…5B and 6; cf. also Kusano et al 1977) although in a few e.r. oocytes a latency as short as 05 see was observed.…”

Section: Resultsmentioning

confidence: 99%

“…Laboratory reared Xenopus are convenient for this study because they provide oocytes at various stages of maturity all year around. For preliminary reports of our results see Kusano, Miledi & Stinnakre (1977.…”

Section: Introductionmentioning

confidence: 99%

Cholinergic and catecholaminergic receptors in the Xenopus oocyte membrane

Kusano

Miledi

Stinnakre

1982

The Journal of Physiology

Self Cite

474

403

View full text Add to dashboard Cite

SUMMARY1. Neurotransmitter-receptors in the membrane of Xenopus oocytes have been studied using electrophysiological techniques. Neurotransmitters and related agents were applied while recording either membrane potential or membrane current. The majority of ovarian oocytes used were at stages IV and V.2. Three types of oocytes were examined: inner ovarian epithelium covered (e.c.) oocytes; epithelium manually removed (e.r.) oocytes; and collagenase treated (c.t.) ooctyes.3. Ovarian oocytes are sensitive to some cholinergic and catecholaminergic agents. Responses to serotonin were seldom observed and when present were much weaker than responses to other agents. No responses were observed to the amino acids: aspartate, glutamate, y-aminobutyric acid, and glycine; or to octopamine and histamine.4. Acetylcholine (ACh) usually depolarized the membrane, in a dose-dependent manner, with threshold concentrations as low as 10-9 M. The ACh-potential was due to an increase in Cl permeability and had a reversal potential around -19 mV. The intracellular Cl ion activity, measured with a Cl-ion sensitive micro-electrode, was about 65 mm and the estimated Cl-ion equilibrium potential, EC1, agreed with the reversal potential of the ACh-potential.5. Curare (10-4 M), tetrodotoxin (10-6 M), or ac-bungarotoxin (10-6 g/ml.) did not block the response to 10-6 M-ACh; whereas atropine (10-7 M) blocked it. No response to nicotinic agents (e.g. nicotine, 1,1-dimethyl-4-phenylpiperazinium) was observed. These results suggest that the ACh receptors in the oocyte membrane are muscarinic in nature.6. The apparent latency ofthe ACh potential, examined by ionophoretic application of ACh to e.r. oocytes and c.t. oocytes, ranged from 0 5 see to over 20 sec. Intracellular injection of ACh was without effect.7. Responses to catecholamines were observed mostly in e.c. oocytes; while in e.r. and c.t. oocytes they were rare and of very small amplitudes.

show abstract

“…Native oocytes exhibit a complex depolarizing response to ACh [2,3]. The signal transduction pathway proposed for the muscarinic response in oocytes includes activation of a phospholipase C, generation of the two intracellular second messengers, inositol 1,4$trisphosphate (IP3) and diacylglycerol and mobilization of calcium.…”

Section: Introductionmentioning

confidence: 99%

Extracellular calcium participates in responses to acetylcholine in Xenopus oocytes

1990

View full text Add to dashboard Cite

We tested the contribution of extracellular calcium (Ca,Z') to membrane electrical responses to acetylcholine (ACh) in native Xenopus oocytes. Removal of Ca, caused a decrease in both the rapid (D,) and the slow (D,) chloride currents that comprise the common depolarizing response to ACh in native oocyte. The effect of Caz' removal on the muscarinic response was mimicked by the addition of 1 mM Mn2+, an effective antagonist of calcium influx, though not by antagonists of voltage-sensitive calcium channels. When oocytes were challenged with ACh in Cazf-free medium, subsequent addition of 1.8 mM CaCI, resulted in a rapid, often transient, depolarizing current. Similarly to the Cai+-dependent component of membrane electrical responses, the Ca2' 2+ -evoked current was reversibly abolished by Mn , though not by antigonists of voltage-sensitive calcium channels. Depletion of cellular calcium potentiated the Caz+ -evoked current, implying negative feedback of calcium channels by calcium. Injection of l&l00 fmol of inositol 1,4,5-trisphosphate (IP,) resulted in a two-component depolarizing current. IP, injection promoted the appearance of Ca,2+-evoked current that was significantly potentiated by previous calcium depletion. We suggest that activation of cell-membrane muscarinic receptors causes opening of apparently voltage-insensitive and verapamil or diltiazem-resistant calcium channels. These channels may be activated by IP, or its metabolites, which increase following the activation of cell membrane receptors coupled to a phospholipase C. The channels may be identical to receptor-operated channels described in other model systems.

show abstract

Acetylcholine receptors in the oocyte membrane

Cited by 183 publications

References 5 publications

Electrical currents through full-grown and maturing Xenopus oocytes.

Electrical currents through full-grown and maturing Xenopus oocytes.

Cholinergic and catecholaminergic receptors in the Xenopus oocyte membrane

Extracellular calcium participates in responses to acetylcholine in Xenopus oocytes

Contact Info

Product

Resources

About