Sodium and calcium components of action potentials in <i>Aplysia</i> giant neurone

Geduldig, D.; Junge, Douglas

doi:10.1113/jphysiol.1968.sp008657

Cited by 209 publications

(87 citation statements)

References 28 publications

(29 reference statements)

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“…This agrees with the result obtained from other receptors (Fulpius & Baumann, 1969 Geduldig & Junge (1968). The experiments of the latter workers showed that the dependence of the membrane potential at the peak of the spike upon Na+ or Ca2+ concentration is substantially smaller than the Nernst slope if the concentration of one species is altered in the presence of the other.…”

Section: Voltage Clamp Of Barnacle Photoreceptors 397supporting

confidence: 81%

Membrane properties of a barnacle photoreceptor examined by the voltage clamp technique

Brown¹,

Hagiwara²,

Koike³

et al. 1970

The Journal of Physiology

199

125

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SUMMARY1. Electrical properties of the membrane of photoreceptor cells in the lateral ocelli of barnacles, Balanus amphitrite and B. eburneus were investigated by intracellular recording, polarization and voltage-clamp techniques.2. The resting potential of a dark adapted cell was 36.3 + 6-6 mV (S.D.) and depended-mainly on the external K+ concentration.3. Current-voltage relations obtained from voltage-clamp experiments in the absence of light were non-linear and varied with time after the onset of a step change in membrane potential; the steady state was reached after about 0 5 sec.4. Illumination resulted in a membrane potential change under current clamp and in a change of membrane current (light-initiated membrane current (L.I.C.): total membrane current with illumination minus current without illumination) under voltage-clamp conditions. Amplitudes and time course of L.I.C. depended on the light intensity as well as membrane potential.5. The L.I.C.-voltage relation was non-linear and corresponded with a slope conductance increase with increasing positive membrane potential.6. The reversal potential of L.I.C. was independent of the light intensity and the time after onset of illumination; the average value obtained in normal saline was + 26-9 + 5 0 mV.7. The membrane conductance estimated from instantaneous L

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Section: Voltage Clamp Of Barnacle Photoreceptors 397supporting

confidence: 81%

Membrane properties of a barnacle photoreceptor examined by the voltage clamp technique

Brown¹,

Hagiwara²,

Koike³

et al. 1970

The Journal of Physiology

199

125

View full text Add to dashboard Cite

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“…In the presence of SKF 525A cocaine neither shifted the dose-response curve nor increased the maximum response. This is supported by the findings of Shibata et al, 1971, who showed in rabbit aortic strips that cocaine does not potentiate the response to noradrenaline in Ca2+ free medium or in the presence of Mn2 + or Co2+ which aire thought to inhibit specifically Ca2 +influx (Hagiwran & Nakajima, 1966;Geduldig & Junge, 1968;Shibata, 1969). In addition, in the same preparation, cocaine effectively potentiated the contraction produced when Ca2`was added to a Ca2+-free, high K+ medium.…”

Section: The Effect Of Cocaine On Responses To Angiotensinsupporting

confidence: 75%

Investigation of the Role of Calcium in the Super‐sensitivityproduced by Cocaine in Cat Spleen Strips

Summers

Tillman

1979

British J Pharmacology

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Cocaine (2 × 10−6m and 10−5m) produced 2 and 7 fold shifts to the left of the dose‐response curve to (—)‐noradrenaline recorded isotonically in isolated splenic capsular strips of the cat. The same concentrations of cocaine also produced increases in the maximum response of the tissue to 117% and 126.7% of control. Desmethylimipramine (DMI, 10 −7 to 10−6m) produced no significant potentiation of the response of cat spleen strips to (—)‐noradrenaline. At 10−5 M DMI decreased the maximum response. Cocaine (10−5m) produced a 3.3 fold shift to the left of the dose‐response curve whereas DMI (10−6m) had no effect on the dose‐response curve to oxymetazoline in cat splenic capsular strips. Cocaine (10−5m) in the presence of phentolamine (10−6m) produced a shift to the left and an increase in the maximum response to K+, an agonist which is believed to produce muscle contraction by increasing the membrane calcium flux. Cocaine (10−5m) had no effect on the dose‐response curve to angiotensin which is believed to contract vascular muscle by releasing calcium from intracellular storage sites. The potentiating effect of cocaine (10−5m) on responses of spleen strips to (—)‐noradrenaline was blocked by the calcium flux inhibitor SKF 525A (2.65 × 10−5m). It is concluded that the results are compatible with the view that cocaine enhances the influx of calcium across the cell membrane during responses to agonists that utilize the extracellular pool of calcium and that this effect is responsible for a large part of the potentiation of the response.

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“…Effects of TTX, ouabain, TAP, and cooling Tetrodotoxin (TTX) abolishes specifically the fast sodium component of the somatic spike in molluscan neurons (GEDULDING and JUNGE, 1968;ADAMS and GAGE, 1979;GORMAN et al, 1982). 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).…”

Section: Camp Induced Inward Currentmentioning

confidence: 99%

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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Sodium and calcium components of action potentials in Aplysia giant neurone

Cited by 209 publications

References 28 publications

Membrane properties of a barnacle photoreceptor examined by the voltage clamp technique

Membrane properties of a barnacle photoreceptor examined by the voltage clamp technique

Investigation of the Role of Calcium in the Super‐sensitivityproduced by Cocaine in Cat Spleen Strips

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

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