A transition temperature for acetylcholine channel conductance in chick myoballs.

Fischbach, Gerald D.; Lass, Yoram

doi:10.1113/jphysiol.1978.sp012399

Cited by 48 publications

(22 citation statements)

References 22 publications

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“…A similar discrete change of the temperature dependence of membrane properties has been a widespread phenomenon in biological and artificial membranes. Examples are the single channel conductance associated with the glutamate receptor at locust nerve muscle junction (Anderson, Cull-Candy & Miledi, 1978), with the acetylcholine receptor of cultured chick myoballs (Fischbach & Lass, 1978), the rate constants of the asymmetrical charge movement in squid axons (Kimura & Meves, 1979), the kinetic parameters and conductance of the Na channel in the Ranvier node and muscle fibre (Chiu, Mrose & Ritchie, 1979;Schwarz, 1979) and ion carrier or channel-induced conductances in lipid bilayers (Krasne, Eisenman & Szabo, 1971). In the present case, the transition temperature is about 10 'C.…”

Section: Temperature and Anomalous Rectification Discussionmentioning

confidence: 99%

Effect of temperature on the anomalous rectification of the membrane of the egg of the starfish, Mediaster aequalis.

Hagiwara¹,

Yoshii²

1980

The Journal of Physiology

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SUMMARY1. The effect of temperature upon the anomalous or inward rectification of the K conductance in the immature egg membrane of the starfish, Mediaster aequalis, was studied by using voltage clamp technique.2. The K conductance decreases with a relatively small Q10 (1.62) down to about 10 'C; below 10 0C, the Q10 is much greater (5.8 at [K+] 3. The activation of the rectification depends on V -VK, rather than V alone, at all temperatures at constant internal K concentration.4. The K conductance at a given

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Section: Temperature and Anomalous Rectification Discussionmentioning

confidence: 99%

Effect of temperature on the anomalous rectification of the membrane of the egg of the starfish, Mediaster aequalis.

Hagiwara¹,

Yoshii²

1980

The Journal of Physiology

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“…A striking decrease in the single channel conductance below 20°C is described in the accompanying paper (Fischbach & Lass, 1978).…”

Section: Introductionmentioning

confidence: 99%

“…When the cell was hyperpolarized, low frequency components were predominant, and the spectrum was shifted to the left along the frequency axis. The mean channel open time was also prolonged as the preparation was cooled over the range 37°-10 0C (Fischbach & Lass, 1978 (Kuffier & Yoshikami, 1975;Fertuck & Salpeter, 1976).…”

Section: Introductionmentioning

confidence: 99%

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Acetylcholine noise in cultured chick myoballs: a voltage clamp analysis.

Fischbach¹,

Lass²

1978

The Journal of Physiology

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SUMMARY1. Large spherical muscle cells were grown in vitro by allowing dissociated chick myoblasts to fuse in suspension culture.2. Myoball membranes could be adequately voltage clamped even in the face of large inward currents (ca. 100 nA) induced by ACh.3. The single channel conductance, y, estimated from the ratio of the mean to the variance of ACh currents was 25-40 pmho at temperatures between 250 and 37 0C. 4. Spectra of ACh current fluctuations declined with 1/f 2. The mean channel open time (7r) estimated from the half-power frequency was 2 msec at 37 0C and -90 mV holding potential. At lower membrane potentials 7 was decreased and on hyperpolarization r was prolonged.

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“…Exposure of vesicles to 0.01% Triton X-100 neither perturbed membrane ultrastructure nor increased the fraction of vesicles permeable to LPO. Since that concentration was known to have a profound effect on functional properties of nicotinic receptors (37,38), attention was focused on other detergents . Saponin and digitonin were found to cause a concentration-dependent increase in the permeability of the vesicles to LPO and, of the two, saponin produced that effect without grossly altering the vesicle morphology.…”

Section: Alteration Of Vesicle Permeabilitymentioning

confidence: 99%

Nicotinic postsynaptic membranes from Torpedo: sidedness, permeability to macromolecules, and topography of major polypeptides.

John

Froehner

Goodenough

et al. 1982

The Journal of Cell Biology

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Experiments were conducted to examine the topographic arrangement of the polypeptides of the acetylcholine receptor (AcChR) and the nonreceptor M, 43,000 protein in postsynaptic membranes isolated from Torpedo electric organ. When examined by electron microscopy, >85% of vesicles were not permeable to ferritin or lactoperoxidase (LPO) . Exposure to saponin was identified as a suitable procedure to permeabilize the vesicles to macromolecules with minimal alteration of vesicle size or ultrastructure . The sidedness of vesicles was examined morphologically and biochemically. Comparison of the distribution of intramembrane particles on freeze-fractured vesicles and the distribution found in situ indicated that >85% of the vesicles were extracellular-side out. Vesicles labeled with a-bungarotoxin (a-BgTx) were reacted with antibodies against a-BgTx or against purified AcChR of Torpedo. Bound antibodies were detected by the use of ferritin-conjugated goat anti-rabbit antibody and were located on the outside of >99% of labeled vesicles . Similar results were obtained for normal vesicles or vesicles exposed to saponin. Quantification of the amount of [3 H]-a-BgTx bound to vesicles before and after they were made permeable with saponin indicated that <5% of aBgTx binding sites were cryptic in normal vesicles . It was concluded that >95% of postsynaptic membranes were oriented extracellular-side out.LPO-catalyzed radioiodinations were performed on normal and saponin-treated vesicles and on vesicles from which the Mr (relative molecular mass) 43,000 protein had been removed by alkaline extraction . In normal vesicles, polypeptides of the AcChR were iodinated while the Mr 43,000 protein was not. In vesicles made permeable with saponin, the pattern of labeling of AcChR polypeptides was unchanged, but the M, 43,000 protein was heavily iodinated. The relative iodination of AcChR polypeptides was unchanged in membranes equilibrated with agonist or with a-BgTx or after alkaline-extraction. It was concluded that the M, 43,000 protein is present on the intracellular surface of the postsynaptic membrane and that AcChR polypeptides are exposed on the extracellular surface.Analysis ofthe mechanism of permeability control by nicotinic cholinergic receptors is facilitated by the isolation ofthe plasma membrane of the innervated Torpedo electrocyte surface, which is highly enriched in nicotinic receptors (for a review, see reference 1). The nicotinic receptor (AcChR), which constitutes -r50% of the protein in the purified postsynaptic membrane, is composed of polypeptides of apparent molecular weights

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A transition temperature for acetylcholine channel conductance in chick myoballs.

Cited by 48 publications

References 22 publications

Effect of temperature on the anomalous rectification of the membrane of the egg of the starfish, Mediaster aequalis.

Effect of temperature on the anomalous rectification of the membrane of the egg of the starfish, Mediaster aequalis.

Acetylcholine noise in cultured chick myoballs: a voltage clamp analysis.

Nicotinic postsynaptic membranes from Torpedo: sidedness, permeability to macromolecules, and topography of major polypeptides.

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