Properties of single calcium channels in the neuronal membrane

Krishtal, O. A.; Didoplichko, V.I.; Shakhovalov, Yu.A.

doi:10.1016/s0022-0728(80)80229-4

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…A successive kinetic model with one open state has been proposed for calcium channels by several investigators (Krishtal, Pidoplichko & Shakhovalov, 1980;Byerly et al 1984 In the present experiments such time constants have been measured precisely in a wide range of repolarization potentials (which is not possible during single-channel recordings), and the results obtained were a good fit with the theoretical predictions.…”

Section: P G Kostyilk and R E Shirokovsupporting

confidence: 60%

“…Sinice the recording system used in our experiments has a limited time resolution, it permitte(d us to analyse only slow components of the deactivation process reflecting its limiting stages; we do not exclude the possible presence of the other components with very short (below 100 ,us) and/or very long (several seconds) time constants. A successive kinetic model with one open state has been proposed for calcium channels by several investigators (Krishtal, Pidoplichko & Shakhovalov, 1980;Byerly et al 1984):…”

Section: Discussionmentioning

confidence: 99%

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Deactivation kinetics of different components of calcium inward current in the membrane of mice sensory neurones.

Kostyuk

Shirokov

1989

The Journal of Physiology

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SUMMARY1. Deactivation kinetics of different components of calcium inward current were analysed by measuring 'tail currents' in intracellularly perfused sensory neurones isolated from dorsal root ganglia of newborn mice.2. Deactivation of a low-threshold inactivating component had a monoexponential time course with time constants that decreased as the potential was made more negative, and reached a limiting value of 10-1-2 ms at extreme hyperpolarizations. Replacement of Ca2' by Ba2+ as a charge carrier decreased this value almost twofold.3. Deactivation of the high-threshold component of calcium current contained two exponential components with time constants of similar potential dependence. The fast time constant became practically constant (0-1-02 ms) during repolarizations beyond -50 mV, and the slow time constant became constant (0-80-0-85 ms) at repolarization beyond -70 mV.4. Replacement of intracellular aspartate with phosphate, or a depolarized holding potential of -40 mV, abolished reversibly the slow component of the tail current; in parallel, the peak current-voltage relation of the current became shifted by 15-20 mV in the depolarizing direction.5. Extracellular application of the calcium channel agonist Bay K 8644 (2-5-5 umol/l) did not change deactivation kinetics of the low-threshold current; however, it increased considerably the slow exponential component of high-threshold current deactivation or induced such a component in conditions when the latter was absent before application (Vh = -40 mV; cell perfusion with Tris phosphate).6. The data obtained are analysed on the basis of the presence of three types of calcium channels in the neuronal membrane which possess similar kinetic mechanisms of activation and deactivation but differ in the activation thresholds and the time constants of transitions between open and closed states. The three calcium channels differ also in interaction with different permeant ions and calcium channel agonists.

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Section: P G Kostyilk and R E Shirokovsupporting

confidence: 60%

Section: Discussionmentioning

confidence: 99%

Deactivation kinetics of different components of calcium inward current in the membrane of mice sensory neurones.

Kostyuk

Shirokov

1989

The Journal of Physiology

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“…However, spectrum analysis of calcium current fluctuations and direct analysis of single calcium channel activity have shown the insufficiency of the proposed model. The data obtained led to the assumption about the presence of a fast potential-independent kinetic stage that precedes the open state of the channel (Krishtal, Pidoplichko & Shakhovalov, 1980;Fenwick, Marty & Neher, 1982;Brown, Tsuda & Wilson, 1983;Hagiwara & Byerly, 1983;Hagiwara & Ohmori, 1983;Brown, Lux & Wilson, 1984;Shuba & Savchenko, 1985). Both approaches to the understanding of kinetic mechanisms of calcium channels are little related to each other.…”

Section: Introductionmentioning

confidence: 99%

Activation kinetics of single high-threshold calcium channels in the membrane of sensory neurons from mouse embryos

1989

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Activation kinetics of single high-threshold inactivating (HTI or N-type) calcium channels of cultured dorsal root ganglion cells from mouse embryos was studied using a patch-clamp method. Calcium channels displayed bursting activity. The open-time histogram was single exponential with an almost potential-independent mean open time tau op = 1.2 msec. The closed-time histogram was multicomponent; at least three of the components were associated with the activation process. The "fast" exponential component with the potential-independent time constant tau fcl = 0.9 msec included all intraburst gaps, while two "slower" ones with potential-dependent time constants tau scl and tau vscl described shut times between bursts and between clusters of bursts. The burst length histogram was biexponential. The "fast" component with a relatively potential-independent time constant tau fbur = 0.6 msec described short, isolated channel openings while the "slow" component characterized real bursts with a potential-dependent mean life time. The waiting-time histogram could be fitted by a difference of two exponentials with time constants being the same as tau scl and tau vscl. The data obtained were described in the frame of a 4-state sequential model of calcium channel activation, in which the first two stages are formally attributed to potential-dependent transmembrane transfer of two charged gating particles accompanying the channel transitions between three closed states, and the third one to fast conformational changes in channel protein leading to the opening of the channel. The rate constants for all transitions were defined. The validity of the proposed model for both low-threshold inactivating (LTI or T-type) and high-threshold noninactivating (HTN or L-type) calcium channels is discussed.

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Chapter 17 The Regulation of Calcium in the Intact Retinal Rod: A Study of Light-Induced Calcium Release by the Outer Segment

Gold

Korenbrot

1981

Current Topics in Membranes and Transport

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Properties of single calcium channels in the neuronal membrane

Cited by 3 publications

References 11 publications

Deactivation kinetics of different components of calcium inward current in the membrane of mice sensory neurones.

Deactivation kinetics of different components of calcium inward current in the membrane of mice sensory neurones.

Activation kinetics of single high-threshold calcium channels in the membrane of sensory neurons from mouse embryos

Chapter 17 The Regulation of Calcium in the Intact Retinal Rod: A Study of Light-Induced Calcium Release by the Outer Segment

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