Ca2+ release from internal stores: role in generating depolarizing after‐potentials in rat supraoptic neurones.

Li, Z; Hatton, Glenn I.

doi:10.1113/jphysiol.1997.sp021862

Cited by 77 publications

(70 citation statements)

References 38 publications

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“…12) (Li and Hatton 1997a). With all other conductances and the total CAN conductance maintained constant, the simulated compartmental distribution of CAN channels in the soma and primary dendrites gave the best correspondence with the DAP amplitude and dynamics observed in MNCs recorded in slices (g CAN,s =45 μS/cm 2 , g CAN,pd =90 μS/cm 2 and g CAN,sd =0 (Fig.…”

Section: Distribution Of the Dap Conductance (G Can )-mentioning

confidence: 66%

“…Two mechanisms have been proposed and backed up with experimental findings: the blockade of a resting K + current (Li and Hatton 1997a) and the generation of a Ca 2+ -dependent, non-selective cation, or CAN, current (Ghamari-Langroudi and Bourque 2002). We selected the CAN current mechanism in our model for the following reasons.…”

Section: Ionic and Compartmental Mechanisms Of The Dapmentioning

confidence: 99%

“…Current-voltage curves for the L-type currents were fitted with a double Boltzmann function, and for the N-type current with a single Boltzmann function. Empty circles and dotted lines correspond to the experimental data (taken from Joux et al 2001), filled circles and solid lines correspond to the model currents Li and Hatton 1997a). The DAP is not seen at a membrane potential of −70 mV (b4), appears at −60 mV, and increases in size with membrane depolarization (b1,b2) until it reaches spike threshold and is masked by repetitive spiking activity (b1).…”

Section: A3 Intercompartmental Coupling Currentsmentioning

confidence: 99%

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Somato-dendritic mechanisms underlying the electrophysiological properties of hypothalamic magnocellular neuroendocrine cells: A multicompartmental model study

2007

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Magnocellular neuroendocrine cells (MNCs) of the hypothalamus synthesize the neurohormones vasopressin and oxytocin, which are released into the blood and exert a wide spectrum of actions, including the regulation of cardiovascular and reproductive functions. Vasopressin-and oxytocinsecreting neurons have similar morphological structure and electrophysiological characteristics. A realistic multicompartmental model of a MNC with a bipolar branching structure was developed and calibrated based on morphological and in vitro electrophysiological data in order to explore the roles of ion currents and intracellular calcium dynamics in the intrinsic electrical MNC properties. The model was used to determine the likely distributions of ion conductances in morphologically distinct parts of the MNCs: soma, primary dendrites and secondary dendrites. While reproducing the general electrophysiological features of MNCs, the model demonstrates that the differential spatial distributions of ion channels influence the functional expression of MNC properties, and reveals the potential importance of dendritic conductances in these properties.

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Section: Distribution Of the Dap Conductance (G Can )-mentioning

confidence: 66%

Section: Ionic and Compartmental Mechanisms Of The Dapmentioning

confidence: 99%

Section: A3 Intercompartmental Coupling Currentsmentioning

confidence: 99%

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Somato-dendritic mechanisms underlying the electrophysiological properties of hypothalamic magnocellular neuroendocrine cells: A multicompartmental model study

2007

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“…In fact, direct Ca 2ϩ channel modulation is unlikely because DAPs are still inhibited by -agonist concentrations that are too low to affect calcium channels, and furthermore -agonists do not affect other calcium-dependent processes, such as action-potential broadening (Brown et al, 1999). In addition, aside from Ca 2ϩ influx, the DAP is known to be controlled by release from stores (Li and Hatton, 1997a), and so a direct reduction of influx should only partially inhibit the plateau. Nevertheless, it is sensible to consider how this alternative modulation might affect our model.…”

Section: Synaptic Inputmentioning

confidence: 99%

“…We showed previously (Roper et al, 2003) that calcium only rises in response to an action potential and that there is little, if any, subthreshold calcium entry; thus, we assumed that [Ca 2ϩ ] i is only increased by influx through high-voltage-activated calcium channels. However, our model could easily be extended to include other spike-dependent calcium sources, such as calcium-induced calcium release (Li and Hatton, 1997a), without affecting our main conclusions.…”

Section: Introductionmentioning

confidence: 99%

Burst Initiation and Termination in Phasic Vasopressin Cells of the Rat Supraoptic Nucleus: A Combined Mathematical, Electrical, and Calcium Fluorescence Study

Roper¹,

Callaway²,

Armstrong³

2004

J. Neurosci.

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Vasopressin secreting neurons of the rat hypothalamus discharge lengthy, repeating bursts of action potentials in response to physiological stress. Although many electrical currents and calcium-dependent processes have been isolated and analyzed in these cells, their interactions are less well fathomed. In particular, the mechanism of how each burst is triggered, sustained, and terminated is poorly understood. We present a mathematical model for the bursting mechanism, and we support our model with new simultaneous electrical recording and calcium imaging data. We show that bursts can be initiated by spike-dependent calcium influx, and we propose that the resulting elevation of bulk calcium inhibits a persistent potassium current. This inhibition depolarizes the cell above threshold and so triggers regenerative spiking and further calcium influx. We present imaging data to show that bulk calcium reaches a plateau within the first few seconds of the burst, and our model indicates that this plateau occurs when calcium influx is balanced by efflux and uptake into stores. We conjecture that the burst is terminated by a slow, progressive desensitization to calcium of the potassium leak current. Finally, we propose that the opioid dynorphin, which is known to be secreted from the somatodendritic region and has been shown previously to regulate burst length and phasic activity in these cells, is the autocrine messenger for this desensitization.

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Magnocellular Neurons and Posterior Pituitary Function

Brown

2016

Comprehensive Physiology

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The posterior pituitary gland secretes oxytocin and vasopressin (the antidiuretic hormone) into the blood system. Oxytocin is required for normal delivery of the young and for delivery of milk to the young during lactation. Vasopressin increases water reabsorption in the kidney to maintain body fluid balance and causes vasoconstriction to increase blood pressure. Oxytocin and vasopressin secretion occurs from the axon terminals of magnocellular neurons whose cell bodies are principally found in the hypothalamic supraoptic nucleus and paraventricular nucleus. The physiological functions of oxytocin and vasopressin depend on their secretion, which is principally determined by the pattern of action potentials initiated at the cell bodies. Appropriate secretion of oxytocin and vasopressin to meet the challenges of changing physiological conditions relies mainly on integration of afferent information on reproductive, osmotic, and cardiovascular status with local regulation of magnocellular neurons by glia as well as intrinsic regulation by the magnocellular neurons themselves. This review focuses on the control of magnocellular neuron activity with a particular emphasis on their regulation by reproductive function, body fluid balance, and cardiovascular status. © 2016 American Physiological Society. Compr Physiol 6:1701-1741, 2016.

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Ca2+ release from internal stores: role in generating depolarizing after‐potentials in rat supraoptic neurones.

Abstract: 1. Influences of Ca2+ release from internal stores on the generation of depolarizing afterpotentials (DAPs) were investigated in magnocellular neurones of rat supraoptic nucleus (SON) using whole-cell patch recording techniques in brain slices.

Cited by 77 publications

References 38 publications

Somato-dendritic mechanisms underlying the electrophysiological properties of hypothalamic magnocellular neuroendocrine cells: A multicompartmental model study

Somato-dendritic mechanisms underlying the electrophysiological properties of hypothalamic magnocellular neuroendocrine cells: A multicompartmental model study

Burst Initiation and Termination in Phasic Vasopressin Cells of the Rat Supraoptic Nucleus: A Combined Mathematical, Electrical, and Calcium Fluorescence Study

Magnocellular Neurons and Posterior Pituitary Function

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