Current-voltage relationships of repetitively firing neurons

Partridge, Lloyd D.; Thompson, Stuart H.; Smith, Stephen J.; Connor, John A.

doi:10.1016/0006-8993(79)90007-6

Cited by 31 publications

(20 citation statements)

References 20 publications

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“…In any case our results demonstrate that the SIC underlying the NSR region is present in the non-bursting neuron L5 of Aplysia kurodai. In Archidoris non-brusting neurons the I V curve shows a subthreshold NSR region which is more likely due to a Na+ process than a Ca2+ process (PARTRIDGE et al 1979). Thus, I -V curves with NSR regions are not unique to bursting neurons.…”

Section: Discussionmentioning

confidence: 95%

“…However, in molluscan pacemaker neurons, including cell R15, there is evidence that the slow inward current is carried by Na{ ions through a channel which is insensitive to TTX (SMITH et a!., 1975;KONONENKO, 1978;CARNEVALE and WACHTEL, 1980) or by both Na+ and Ca2+ ions (JOHNSTON, 1976;PARTRIDGE et al, 1979). Perfusion for 28 min with 50 ,uM TTX, which usually abolishes the fast Na+ inward current of molluscan neurons, did not change the amplitude or duration of the cAMP-induced inward current recorded at a holding potential of -50 mV (Fig.…”

Section: Camp Induced Inward Currentmentioning

confidence: 87%

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Influences of pressure-injected cyclic AMP on the membrane current and characteristics of an identified neuron of Aplysia kurodai.

1985

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The ionic mechanism of the effect of intracellularly injected adenosine 3',5'-cyclic monophosphate (CAMP) on the membrane of identified neuron L5 of Apl ysia kurodai was investigated with conventional voltage-clamp and ion-substitution techniques. The intracellular elevation of CAMP caused an inward current ('CAMP), which was not accompanied by a significant change in membrane conductance at potentials more hyperpolarized than -60 mV. The current increased over the voltage range (-50 to -30 mV) associated with a conductance decrease and decreased at potentials more hyperpolarized than -60 mV. Elevated intracellular CAMP was found to enhance a region of negative slope resistance in steady-state I -V relations. Duration of the 'CAMP was greatly prolonged by bath-applied isobutylmethylxanthine (50 ,uM), but imidazole (10 mM) had an opposite effect on the 'CAMP. Tolbutamide (5 mM), a protein kinase inhibitor, reduced the DAMP. The current was not affected by the presence of bath-applied TTX (50 µM), ouabain (50 /LM), or triaminopyrimidine (5 mM). Reduction of [Na+]o reversibly decreased the DAMP. Li+ could largely substitute for Nat Alterations of [K+]o, and bath application of 4-AP (5 mM) and TEA (30 mM) did not affect the DAMP, In the presence of Nat, Cl-, and divalent cations such as Ca2+ and Ba2+ inhibited the DAMP. These results suggest that fast elevation of intracellular cAMP induces a TTX-resistant slow Na+ inward current, and the current might be due to activation of CAMP-dependent protein kinase.

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Section: Discussionmentioning

confidence: 95%

Section: Camp Induced Inward Currentmentioning

confidence: 87%

Influences of pressure-injected cyclic AMP on the membrane current and characteristics of an identified neuron of Aplysia kurodai.

1985

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“…2A. A current-voltage relation which contains a region of negative slope conductance and hysteresis is found in both pace-maker and in non-pacemaker cells (Gola, 1976;190 Partridge, Thompson, Smith & Connor, 1979) and it has been shown that a negative slope conductance need not accompany pace-maker activity in some cells under all conditions (Partridge, 1975). Moreover, in attempting to determine the ionic basis of the currents underlying the dynamic current-voltage relation shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

Ionic requirements for membrane oscillations and their dependence on the calcium concentration in a molluscan pace‐maker neurone

Gorman

Hermann

Thomas

1982

The Journal of Physiology

127

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SUMMARY1. Membrane currents from the bursting pace-maker neurone R-15 of Aplyia were measured under conditions designed to simulate membrane oscillations. Changes in the absorbance of the Ca2+-sensitive dye arsenazo III were used to monitor changes in the free intracellular Ca2+ concentration, [Ca] 2. In normal external ionic conditions the depolarizing phase of pace-maker activity was associated with a slow inward current and the hyperpolarizing phase with a slow outward current.3. In cells where the early inward Na+ current was blocked by tetrodotoxin and outward K+ currents were suppressed by intracellular EGTA and extracellular tetraethylammonium and 4-aminopyridine, the slow inward current was significantly larger in amplitude and was suppressed by removal of external Ca2+ or the addition of external La3+, but not by the removal of external Na+.4. The slow inward current was increased when [Ca]0 was raised and decreased when it was reduced in the manner expected for current flow through a Ca2+ channel. The selectivity of the slow inward current for divalent cations was Ca2+ > Sr2+ > Ba2+ > Mn2+.5. The slow inward current was only slightly reduced by a 10°C reduction in temperature.6. In normal external and internal ionic conditions changes in dye absorbance occurred when the membrane was depolarized with slow triangular voltage ramps or long depolarizing steps within the pace-maker oscillation range. The absorbance change, and thus the increase in Ca2+, [Ca]

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“…At both the macroscopic and singlechannel level, this conductance is nonselective for cations, Ca 2ϩ sensitive, voltage dependent, and non-inactivating (Wilson and Kaczmarek, 1993;Wilson et al, 1996;Magoski et al, 2002;Lupinsky and Magoski, 2004). Similar currents have been documented as underlying bursting in many, functionally diverse neurons from various species (Wilson and Wachtel, 1974;Partridge et al, 1979;Green and Gillette, 1983;Stafstrom et al, 1985;Swandulla and Lux, 1985;Alonso and Llinas, 1989;Rekling and Feldman, 1997;Beurrier et al, 1999;Morisset and Nagy, 1999;Egorov et al, 2002). In the bag cell neurons, PKC activity is elevated at the start of the afterdischarge (Wayne et al, 1999).…”

Section: Discussionmentioning

confidence: 76%

Association/Dissociation of a Channel–Kinase Complex Underlies State-Dependent Modulation

Magoski¹,

Kaczmarek²

2005

J. Neurosci.

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Although ion channels are regulated by protein kinases, it has yet to be established whether the behavioral state of an animal may dictate whether or not modulation by a kinase can occur. Here, we describe behaviorally relevant changes in the ability of a nonselective cation channel from Aplysia bag cell neurons to be regulated by protein kinase C (PKC). This channel drives a prolonged afterdischarge that triggers the release of egg-laying hormone and a series of reproductive behaviors. The afterdischarge is followed by a lengthy refractory period, during which additional bursting cannot be elicited. Previously, we reported that, in excised inside-out patches, the cation channel is closely associated with PKC, which increases channel activity. We now show that this channel-kinase association is plastic, because channels excised from certain neurons lack PKC-dependent modulation. Although direct application of PKC-activating phorbol ester to these patches had no effect, exposing the neurons themselves to phorbol ester reinstated modulation, suggesting that an absence of modulation was attributable to a lack of associated kinase. Furthermore, modulation was restored by pretreating neurons with either PP1 [4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine] or SU6656, inhibitors of Src tyrosine kinase, an enzyme whoseSrc homology 3 domain is required for channel-PKC association. Neurons that were stimulated to afterdischarge and had entered the prolonged refractory period were found to have more phosphotyrosine staining and less channel-PKC association than unstimulated neurons. These findings suggest that Src-dependent regulation of the association between the cation channel and PKC controls both the long-term excitability of these neurons and their ability to induce reproduction.

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Current-voltage relationships of repetitively firing neurons

Cited by 31 publications

References 20 publications

Influences of pressure-injected cyclic AMP on the membrane current and characteristics of an identified neuron of Aplysia kurodai.

Influences of pressure-injected cyclic AMP on the membrane current and characteristics of an identified neuron of Aplysia kurodai.

Ionic requirements for membrane oscillations and their dependence on the calcium concentration in a molluscan pace‐maker neurone

Association/Dissociation of a Channel–Kinase Complex Underlies State-Dependent Modulation

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