Effect of pentobarbital on Na and Ca action potentials in an invertebrate neuron

Goldring, J. M.; Blaustein, Mordecai P.

doi:10.1016/0006-8993(82)90222-0

Cited by 15 publications

(4 citation statements)

References 27 publications

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“…(cf. Goldring & Blaustein 1982); but since the potentials are not generally smaller in the baboon, it does not seem likely that the difference is due to a species difference in the sensitivity to Nembutal. Another possibility is species differences in the proportion between fast and slow motor units within a muscle; but it is noteworthy that, among the ankle extensors, a similar scaling down of the amplitude of the la-aggregate occurs in sol.…”

Section: The Amount Of Lmentioning

confidence: 90%

The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

Hongo

Lundberg

Phillips

et al. 1984

Proc. R. Soc. Lond. B.

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The pattern of la-connections to motor nuclei of 17 hindlimb muscles (or groups of muscles) has been investigated in baboons by intracellular recording of Ia-e.ps.p.s evoked in motoneurons from different muscle nerves. The amplitudes are normalized to 70 mV resting potential and compared with similarly normalized Ia-e.ps.p.s in cats. As in the cat, la-excitation is drawn from a restricted number of muscles and the homonymous effect is usually dominating. Heteronymous connections to many motor nuclei are different in the two species. For example, hip extensors are generally more la-isolated from each other in baboons than in cats, and also knee flexors have fewer Iainterconnections than in cats. A unidirectional Ia-synergism between some hip extensors and knee flexors in cats has changed to a bidirectional one in baboons, with a tendency to lateralization of the connections. Among ankle extensors, soleus has smaller heteronymous I a-connections from its synergic ankle extensors than in cats. In baboons, plantaris is heteronymously I a-excited from gastrocnemius-soleus but not from the intrinsic plantar muscles; whereas in cats there exists a considerable la-projection from the intrinsic plantar muscles but not from gastrocnemius-soleus. There is a corresponding difference in the insertion of the plantaris tendon, which shows that this muscle acts as toe extensor in cats but as ankle extensor in baboons. For most of the motor nuclei, the homonymous as well as the total aggregate of Ia-e.ps.p.s is smaller in the baboon than in the cat; but the amplitude range between different motor nuclei is larger in the baboon. Reciprocal Ia-i.ps.p.s are evoked only after spinal transection or when brain function is depressed. It is postulated that baboons, contrary to cats, have descending tonic inhibition of transmission in the reciprocal la-inhibitory pathway. The phylogenetic flexibility of I a-connections is discussed and contrasted with their ontogenetic stability.

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Section: The Amount Of Lmentioning

confidence: 90%

The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

Hongo

Lundberg

Phillips

et al. 1984

Proc. R. Soc. Lond. B.

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“…Barbiturates elicit a bewildering number of actions upon neuronal tissue including the reduction of excitability by inhibition of voltage-dependent currents. For example they reduce the duration of calcium-dependent action potentials (Goldring & Blaustein, 1982;Heyer & MacDonald, 1982) and inhibit voltage-dependent calcium currents in invertebrate (Nishi & Oyama, 1983;Ikemoto et al, 1986) and vertebrate neurones (Gross & Macdonald, 1988). Pentobarbitone has been reported to reduce the amplitude of voltage-activated sodium and potassium conductances (Blaustein, 1968;Narahashi et al, 1971;Sevcik, 1980;Zbicz & Wilson, 1981), probably via the uncharged form of the molecule (Blaustein, 1968;Narahashi et al, 1971;Zbicz & Wilson, 1981).…”

Section: Introductionmentioning

confidence: 99%

Barbiturates inhibit ATP‐K⁺ channels and voltage‐activated currents in CRI‐G1 insulin‐secreting cells

Kozlowski

Ashford

1991

British J Pharmacology

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1 Patch-clamp recording techniques were used to examine the effects of barbiturates upon the ATP-K+ channel, and voltage-activated channels present in the plasma membrane of CRI-Gi insulin-secreting cells.2 Thiopentone inhibited ATP-K' channel activity when applied to cell-attached patches or the intracellular or extracellular surface of cell-free patches. Secobarbitone and pentobarbitone were also effective inhibitors of ATP-K+ channels in cell-free patches, whereas phenobarbitone was ineffective. 3 The diabetogenic agent, alloxan, which is structurally related to the barbiturates also produced an inhibition of ATP-K+ channel activity in outside-out patches. 4 Whole-cell ATP-K+ currents were used to quantify the effects of the barbiturates: concentrationinhibition curves for thiopentone, secobarbitone and pentobarbitone resulted in IC50 values of 62, 250 and 360pM respectively. Phenobarbitone at a concentration of 1 mm was virtually ineffective. 5 Calculation of the apparent membrane concentrations for these drugs indicate that for a given degree of ATP-K+ channel inhibition a similar concentration of each barbiturate is present in the membrane. This suggests that hydrophobicity plays a primary role in their mechanism of action. The pH-dependence and additive nature of barbiturate block also indicates a membrane site of action. 6 Thiopentone, (100pM) was also found to inhibit differentially voltage-activated whole-cell currents.The relative potency of thiopentone at this concentration was 0.64, 0.38 and 0.12 for inhibiting Ca2", K+ and Na+ currents respectively when compared with its ability to inhibit the ATP-K+ channel.

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“…Furthermore, the anticonvulsant/hypnotic agent, phenobarbital, appears to act through depression of frequency-dependent spike broadening on neurons of Helix aspersa (Eagan et al, 1987) which could in turn depress excitatory transmission at nerve terminals, possibly a general mechanism for barbiturate actions, and supported by observations of the effects of pentobarbital on Aplysia neurons (Ikemoto et al, 1986). It has been suggested that the sodium and calcium currents underlying the spikes are equally sensitive to pentobarbital (Goldring and Blaustein, 1982) in the giant R2 neuron of Aplysia. Thiopentone, pentobarbitone, phenobarbitone and barbitone, all accelerated the decay phase of the I Ca in Helix aspersa neurons (Nishi and Oyama, 1983a), and pentobarbitone also inhibited its maximum peak amplitude (Nishi and Oyama, 1983b).…”

Section: Actions Of Clinical Anesthetics On Gastropod Molluscsmentioning

confidence: 99%

Sense and Insensibility – An Appraisal of the Effects of Clinical Anesthetics on Gastropod and Cephalopod Molluscs as a Step to Improved Welfare of Cephalopods

et al. 2018

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Recent progress in animal welfare legislation stresses the need to treat cephalopod molluscs, such as Octopus vulgaris, humanely, to have regard for their wellbeing and to reduce their pain and suffering resulting from experimental procedures. Thus, appropriate measures for their sedation and analgesia are being introduced. Clinical anesthetics are renowned for their ability to produce unconsciousness in vertebrate species, but their exact mechanisms of action still elude investigators. In vertebrates it can prove difficult to specify the differences of response of particular neuron types given the multiplicity of neurons in the CNS. However, gastropod molluscs such as Aplysia, Lymnaea, or Helix, with their large uniquely identifiable nerve cells, make studies on the cellular, subcellular, network and behavioral actions of anesthetics much more feasible, particularly as identified cells may also be studied in culture, isolated from the rest of the nervous system. To date, the sorts of study outlined above have never been performed on cephalopods in the same way as on gastropods. However, criteria previously applied to gastropods and vertebrates have proved successful in developing a method for humanely anesthetizing Octopus with clinical doses of isoflurane, i.e., changes in respiratory rate, color pattern and withdrawal responses. However, in the long term, further refinements will be needed, including recordings from the CNS of intact animals in the presence of a variety of different anesthetic agents and their adjuvants. Clues as to their likely responsiveness to other appropriate anesthetic agents and muscle relaxants can be gained from background studies on gastropods such as Lymnaea, given their evolutionary history.

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Effect of pentobarbital on Na and Ca action potentials in an invertebrate neuron

Cited by 15 publications

References 27 publications

The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

Barbiturates inhibit ATP‐K⁺ channels and voltage‐activated currents in CRI‐G1 insulin‐secreting cells

Sense and Insensibility – An Appraisal of the Effects of Clinical Anesthetics on Gastropod and Cephalopod Molluscs as a Step to Improved Welfare of Cephalopods

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Effect of pentobarbital on Na and Ca action potentials in an invertebrate neuron

Cited by 15 publications

References 27 publications

The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

The pattern of monosynaptic I a-connections to hindlimb motor nuclei in the baboon: a comparison with the cat

Barbiturates inhibit ATP‐K+ channels and voltage‐activated currents in CRI‐G1 insulin‐secreting cells

Sense and Insensibility – An Appraisal of the Effects of Clinical Anesthetics on Gastropod and Cephalopod Molluscs as a Step to Improved Welfare of Cephalopods

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Barbiturates inhibit ATP‐K⁺ channels and voltage‐activated currents in CRI‐G1 insulin‐secreting cells