[3H]PN200-110 and [3H]ryanodine binding and reconstitution of ion channel activity with skeletal muscle membranes

Hamilton, Susan L.; Álvarez, Rocío; Fill, Michael; Hawkes, Mary Jane; Brush, K; Schilling, William P.; Stefani, Enrico

doi:10.1016/0003-2697(89)90167-x

Cited by 75 publications

(38 citation statements)

References 17 publications

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“…Bilayer Techniques-Planar bilayers consisting of 8:2 L-␣-phosphatidylethanolamine and L-␣-phosphatidylcholine were formed following the Mueller-Rudin procedure across a 100-m diameter aperture in Teflon cups as described previously (34). The mixture of phospholipids was dissolved in n-decane (Sigma) at a concentration of 50 mg/ml.…”

Section: Sds-page Electrophoresis In One Andmentioning

confidence: 99%

Multiple Classes of Sulfhydryls Modulate the Skeletal Muscle Ca2+ Release Channel

Aghdasi

Zhang

et al. 1997

Journal of Biological Chemistry

100

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Two sulfhydryl reagents, N-ethylmaleimide (NEM), an alkylating agent, and diamide, an oxidizing agent, were examined for effects on the skeletal muscle Ca 2؉ release channel. NEM incubated with the channel for increasing periods of time displays three distinct phases in its functional effects on the channel reconstituted into planar lipid bilayers; first it inhibits, then it activates, and finally it again inhibits channel activity. NEM also shows a three-phase effect on the binding of

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Section: Sds-page Electrophoresis In One Andmentioning

confidence: 99%

Multiple Classes of Sulfhydryls Modulate the Skeletal Muscle Ca2+ Release Channel

Aghdasi

Zhang

et al. 1997

Journal of Biological Chemistry

100

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“…Bilayers were formed from a mixture of palmitoyl-oleoyl-phosphatidylethanolamine, palmitoyl-oleoyl-phosphatidylserine and palmitoyloleoyl-phosphatidylcholine (5 : 3:2, by volume) [18,19], obtained in chloroform from Avanti Polar Lipids (Alabaster, Alabama). The lipid mixture was dried under N2 and redissolved in n-decane at a final concentration of 50 mg/ml.…”

Section: Methodsmentioning

confidence: 99%

Single channel activity of the ryanodine receptor calcium release channel is modulated by FK‐506

1994

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The immunosuppressant drug increased the open probability of ryanodine receptor calcium release channels, formed by incorporation of terminal cisternae vesicles from rabbit skeletal muscle into lipid bilayers, with cis (cytoplasmic) calcium concentrations between 10 -7 M and 10 -3 M. FK-506 increased mean current and channel open time and induced long sojourns at subconductance levels that were between 28% and 38% of the maximum conductance and were distinct from the ryanodine-induced subconductance level at about 45% of the maximum conductance. FK-506 relieved the Ca 2+ inactivation of the ryanodine receptor seen at 10 -3 M Ca 2+. The results are consistent with FK-506 removal of FK-506 binding protein from the ryanodine receptor [15].

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“…This lack of change in electrophoretic migration upon reduction is a characteristic of the α 1 subunit (vs. the α 2 subunit) of dihydropyridine-sensitive calcium channels. Thus, we tentatively identify the peaks indicated in figure 4 as the α 1 subunit of the dihydropyridine-sensitive calcium channel, in the same way as Hamilton et al [25]. …”

Section: Resultsmentioning

confidence: 93%

“…Membranes (500 µg) were incubated with [ 3 H]azidopine (20 n M ) in 50 n M MOPS (pH 7.4) for 30 min at 4°C in the dark, according to Hamilton et al [25]. Nonspecific labeling was determined in the presence of 1 µ M nifedipine.…”

Section: Methodsmentioning

confidence: 99%

Potentiation of Prolactin Secretion following Lactotrope Escape from Dopamine Action

et al. 1999

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Modulation of Ca²⁺ channels has been shown to alter cellular functions. It can play an important role in the amplification of signals in the endocrine system, including the pleiotropically regulated pituitary lactotropes. Prolactin (PRL) secretion is tonically inhibited by dopamine (DA), the escape from which triggers acute episodes of hormone secretion. The magnitude of these episodes is explained by a potentiation of the PRL-releasing action of secretagogues such as thyrotropin-releasing hormone (TRH). While the mechanisms of this potentiation are not fully understood, it is known to be mimicked by the dihydropyridine, L-type Ca²⁺ channel agonist Bay K 8644 and blocked by nifedipine and methoxyverapamil. The potentiation is also blocked by inhibitors of cyclic AMP-dependent protein kinase and protein kinase C. We recently described that the escape from tonic actions of DA results in increased macroscopic Ca²⁺ currents in GH₄C₁ lactotropic clonal cells transfected with a cDNA encoding the long form of the human D₂-DA receptor. Here we show that the withdrawal from DA potentiates the PRL-releasing action of TRH in GH₄C₁/D₂-DAR cells to the same extent as in enriched lactotropes in primary culture. In both experimental models a low density of dihydropyridine receptors was shown by (+)-[³H]PN200-110 binding. Photoaffinity labelling with the dihydropyridine [³H]azidopine revealed a protein consistent with the α₁ subunit of L-type Ca²⁺ channels of 165–170 kDa. In both experimental models, the facilitation of TRH action triggered by the escape from DA was correlated with an enhanced rate of phosphorylation of this putative α₁ subunit, the nature of which was further supported by immunoprecipitation with selective antibodies directed against the α_1C and α_1D subunit of voltage-gated calcium channels. We propose that PKA- and PKC-dependent phosphorylation of the α₁ subunit of high voltage activated, L-type Ca²⁺ channels is responsible for the facilitation of Ca²⁺ currents in lactotropes, and hence for the potentiation of secretagogue-mediated PRL secretion. Thus, phosphorylation of Ca²⁺ channels in endocrine cells may be a mechanism for the regulation of various functions including amplification of hormone secretion.

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[3H]PN200-110 and [3H]ryanodine binding and reconstitution of ion channel activity with skeletal muscle membranes

Cited by 75 publications

References 17 publications

Multiple Classes of Sulfhydryls Modulate the Skeletal Muscle Ca2+ Release Channel

Multiple Classes of Sulfhydryls Modulate the Skeletal Muscle Ca2+ Release Channel

Single channel activity of the ryanodine receptor calcium release channel is modulated by FK‐506

Potentiation of Prolactin Secretion following Lactotrope Escape from Dopamine Action

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