Agonists Bay-K8644 and CGP-28392 open calcium channels reconstituted from skeletal muscle transverse tubules

Affolter, Hubert; Coronado, Roberto

doi:10.1016/s0006-3495(85)83789-9

Cited by 105 publications

(69 citation statements)

References 25 publications

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“…Native tubular membranes incorporated into planar lipid bilayers show calcium channels with much lower conductance and marked voltage dependence [27-291, ruling out the likelihood that the channels studied here correspond to these tubular calcium channels. Moreover, addition of an activating dihydropyridine, such as Bay K 8644 is needed to obtain stable recordings of measurable activity of tubular channels [27,29]. Furthermore, we found modulation by ryanodine for channels which displayed the blockable or the non-blockable behavior (not shown), indicating that the channels studied in this work are indeed ryanodinesensitive SR calcium channels.…”

Section: Febslettersmentioning

confidence: 71%

Sarcoplasmic reticulum release channels from frog skeletal muscle display two types of calcium dependence

Bull

Marengo

1993

FEBS Letters

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Calcium channels derived from sarcoplasmic reticulum of frog skeletal muscle were fused with planar lipid bilayers. Fractional open times displayed two types of calcium dependence: (i) blockable channels showed a bell-shaped calcium dependence with an activation constant of 4.5 PM, a Hill coefficient for activation of 1.46 and a blocking constant of 226 PM, and (ii) non-blockable channels displayed a sigmoidal calcium dependence with an activation constant of 1.1 PM and a Hill coefficient of 1.42, no blocking effect was seen with calcium up to 0.5 mM. These two types of calcium dependence may underlie the coexistence of two different pathways for calcium release in frog skeletal muscle.

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Section: Febslettersmentioning

confidence: 71%

Sarcoplasmic reticulum release channels from frog skeletal muscle display two types of calcium dependence

Bull

Marengo

1993

FEBS Letters

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“…The nature of the recorded channels has been confirmed by using pharmacological agents which allowed us to identify functional Ca21 channels from transverse tubule vesicles. The agonist Bay K 8644 increased open channel probability by prolonging the mean open time as predicted for DHPsensitive Ca21 channels (Affolter & Coronado, 1985). The DHP antagonist nifedipine reduced channel activity by acting both on channel mean open time and amplitude (Affolter & Coronado, 1985;Talvenheimo et al 1987;Ma & Coronado, 1988;MejiaAlvarez et al 1991).…”

Section: Effects Of Control Igg On Ca21 Channelmentioning

confidence: 90%

“…The agonist Bay K 8644 increased open channel probability by prolonging the mean open time as predicted for DHPsensitive Ca21 channels (Affolter & Coronado, 1985). The DHP antagonist nifedipine reduced channel activity by acting both on channel mean open time and amplitude (Affolter & Coronado, 1985;Talvenheimo et al 1987;Ma & Coronado, 1988;MejiaAlvarez et al 1991). The amplitude distribution showed only one level in the presence of nifedipine compared to the three amplitude levels in control conditions.…”

Section: Effects Of Control Igg On Ca21 Channelmentioning

confidence: 90%

The action of amyotrophic lateral sclerosis immunoglobulins on mammalian single skeletal muscle Ca2+ channels.

Magnelli

Sawada

Delbono

et al. 1993

The Journal of Physiology

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SUMMARY1. The planar phospholipid bilayer technique was used to study the T-tubule skeletal muscle dihydropyridine (DHP)-sensitive calcium (Ca2") channel. To improve the signal-to-noise ratio, Ca2" channel activity was recorded using both 800-50 and 500-50 mm NaCl gradients.2. Ca21 channels were characterized by their cation selectivity and pharmacological profile. The mean open time for channels identified by these techniques was increased by the DHP agonist Bay K 8644 (2 /LM), while it was decreased by the DHP antagonist nifedipine (5 /yM). Nifedipine also reduced Ca21 channel amplitude levels.3. Immunoglobulins G (IgG) from three amyotrophic lateral sclerosis (ALS) patients (n = 14 experiments), one myasthenia gravis (MG) patient (n = 3 experiments) and one healthy individual (n = 4 experiments), were tested on Ca21 channel activity at a final concentration of 3 mg/ml. 4. Channel mrean open time, mean closed time and time integral for the current were not modified by normal IgG (n = 4 experiments). Similarly, MG IgG did not reduce channel activity (n = 3 experiments).5. ALS IgG reduced the mean open time of DHP-sensitive Ca21 channel activity in twelve out of fourteen experiments. In addition, in five out of twelve experiments, ALS IgG stabilized the channel to a smaller amplitude level.6. ALS IgG reduced Ca21 channel activity in a side-selective fashion, probably corresponding to the external side of the channel.7. These results suggest that ALS IgG action on DHP-sensitive Ca2+ channels is not mediated by second messengers, thus favouring a direct mechanism for interaction with the DHP receptor complex.

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“…In cardiac muscle cells, nitrendipine enhanced the inward current when the membrane was held at potential levels hyperpolarized to -80 mV (Brown et al, 1986), and it is well known that Bay K 8644 augments the amplitude of the inward current in skeletal, cardiac and smooth muscle cells (Brown et al, 1984;Affolter & Coronado, 1985;Sanguinetti et al, 1986;Reuter et al, 1986;Bean et al, 1986). In the present experiments, facilitatory actions of KW-3049 were observed at concentrations below 100 nM at a holding potential of -80 mV (which was lower than the resting membrane potential of about -70 mV in whole tissue, as determined using the microelectrode method).…”

Section: Discussionmentioning

confidence: 99%

Action of the 1,4‐dihydropyridine derivative, KW‐3049, on the smooth muscle membrane of the rabbit mesenteric artery

Terada

Nakao

Okabe

et al. 1987

British J Pharmacology

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1The effect of 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridine-dicarboxylic acid methyl 1-(phenylmethyl)-3-piperidinyl ester hydrochloride (KW-3049) on the smooth muscle membrane of the rabbit mesenteric artery was investigated using microelectrode and single electrode voltage clamp methods. 2 In whole tissue preparations KW-3049 did not alter the resting membrane potential of the artery, but did inhibit the action potential evoked by a depolarizing current in the presence of 10mM tetraethylammonium (TEA). 3 Using the voltage clamp technique, the effects of KW-3049 on the inward current evoked in solution containing 100 mM BaCl2 were observed. When the membrane was held at -60 mV, KW-3049 inhibited the inward current in a concentration-dependent manner. The inward current evoked by a larger depolarizing pulse was inhibited to a larger extent than that evoked by a smaller one. 4 When the membrane was held at -80 mV, the inward current evoked at test potentials of -10 and 0 mV was enhanced by low concentrations of KW-3049 (below 100 nM). 5 KW-3049 accelerated the rate of inactivation of the inward current and shifted the voltagedependent inactivation curve to the left. 6 KW-3049 has a long-lasting inhibitory action on smooth muscle cells, since the inhibition of the inward current persisted for over I h after the removal of KW-3049. 7 Our results suggest that KW-3049 has a selective and long-lasting action on the Ca channels of the smooth muscle cell membrane of the rabbit mesenteric artery. This agent has both facilitatory and inhibitory actions on the Ca channel, depending on the values of the holding and command potentials.

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Agonists Bay-K8644 and CGP-28392 open calcium channels reconstituted from skeletal muscle transverse tubules

Cited by 105 publications

References 25 publications

Sarcoplasmic reticulum release channels from frog skeletal muscle display two types of calcium dependence

Sarcoplasmic reticulum release channels from frog skeletal muscle display two types of calcium dependence

The action of amyotrophic lateral sclerosis immunoglobulins on mammalian single skeletal muscle Ca2+ channels.

Action of the 1,4‐dihydropyridine derivative, KW‐3049, on the smooth muscle membrane of the rabbit mesenteric artery

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