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Titolo:
ARACHIDONIC-ACID-ACTIVATED MEMBRANE CONDUCTANCES IN DISSOCIATED CARDIAC PARASYMPATHETIC NEURONS FROM NECTURUS
Autore:
MULVANEY JM; PARSONS RL;
Indirizzi:
UNIV VERMONT,COLL MED,DEPT ANAT & NEUROBIOL BURLINGTON VT 05405
Titolo Testata:
Journal of neurophysiology
fascicolo: 4, volume: 74, anno: 1995,
pagine: 1621 - 1627
SICI:
0022-3077(1995)74:4<1621:AMCIDC>2.0.ZU;2-1
Fonte:
ISI
Lingua:
ENG
Soggetto:
SIGNAL TRANSDUCTION; POTASSIUM CURRENT; METABOLITES; CELLS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Physical, Chemical & Earth Sciences
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
19
Recensione:
Indirizzi per estratti:
Citazione:
J.M. Mulvaney e R.L. Parsons, "ARACHIDONIC-ACID-ACTIVATED MEMBRANE CONDUCTANCES IN DISSOCIATED CARDIAC PARASYMPATHETIC NEURONS FROM NECTURUS", Journal of neurophysiology, 74(4), 1995, pp. 1621-1627

Abstract

1. Characteristics of the membrane currents activated by arachidonic acid (AA) in dissociated mudpuppy parasympathetic neurons have been determined using the perforated-patch whole cell recording technique. 2. In a sodium-containing physiological solution with 12.5 mM potassium,AA (10-50 mu M) increased total membrane current produced by either depolarizing or hyperpolarizing voltage steps delivered from a holding potential of -40 mV. Decreasing the external potassium concentration from 12.5 to 2.5 mM shifted the reversal potential of the AA-induced current by 10 mV rather than the similar to 42 mV predicted for a highlypotassium-selective channel. 3. In cells kept in sodium solution plus12.5 mM potassium and treated with 20 mu M nordihydroguaiaretic acid (NDGA), an inhibitor of the lipoxygenase pathway of AA metabolism, AA activated only inward currents following hyperpolarizing voltage steps. In this condition, the shift in reversal potential of the AA-inducedcurrent was 40 mV when extracellular potassium concentration was changed fivefold. Consequently, in cells treated with NDGA, AA appeared toactivate only an inwardly rectifying potassium current. 4. Decreasingthe extracellular chloride concentration by similar to 90% did not alter the reversal potential of the AA-activated current when the extracellular sodium concentration was kept constant and the external potassium concentration was 2.5 mM. In the low-chloride solution, AA potentiated both inward and outward current amplitudes. These results suggested that AA did not activate a chloride current in these cells. 5. In asodium-deficient, N-methyl-D-glucamine (NMG)-containing solution, AA only activated currents for voltage steps to potentials more negative than the holding potential. In the NMG-substituted solution, changing the extracellular potassium concentration fivefold shifted the reversal potential of the AA-induced current by 40 mV. Therefore, in the NMG solution, AA primarily activated an inwardly rectifying potassium current. 6. Exchanging the control solution containing AA to an external solution containing AA and barium (barium blocks the inwardly rectifying potassium current) shifted the current-voltage relationship to more positive voltages such that the extrapolated reversal potential was similar to 0 mV. In other experiments, using the barium-containing solution, the reversal potential for the AA-induced current was -3.3 +/- 2.4 (SE) mV. 7. In conclusion, the results of the present study indicatethat at least two membrane currents are activated in the presence of AA: an inwardly rectifying potassium current and an NDGA-sensitive, sodium-dependent current that has a reversal potential more positive than the potassium equilibrium potential. We suggest the second current component is due to the activation of a nonselective cationic conductance.

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Documento generato il 30/11/20 alle ore 16:54:38