Effects of Gamma-aminobutyric Acid and (-)-baclofen on Calcium and Potassium Currents in Cat Dorsal Root Ganglion Neurones in Vitro

Overview

Journal Br J Pharmacol

Publisher Wiley

Specialty Pharmacology

Date 1986 Dec 1

PMID 2434174

Citations 17

Authors

B Robertson

W R Taylor

Affiliations

Soon will be listed here.

Abstract

Calcium and potassium currents were examined in dialysed, isolated dorsal root ganglion neurones of the cat by use of a single electrode voltage clamp. Two calcium currents were identified, a low threshold inactivating (transient) current and a higher threshold slowly inactivating (sustained) current. Both currents were blocked by 1 mM cadmium and replacement of calcium with manganese, which revealed an underlying nonspecific outward current. The sustained current disappeared with internal dialysis over a period of 20 to 30 min. (-)-Baclofen (100 microM) and gamma-aminobutyric acid (GABA, 100 microM) were found to reduce the peak amplitude of the sustained calcium current, an effect which became more pronounced with increasing concentrations of external magnesium (1-5 mM). In 5 mM external magnesium, 100 microM baclofen reduced the calcium current by 28%. The voltage-activated delayed rectifier appeared to be the most prominent potassium current in these cells. We were unable to find any evidence for a significant contribution from calcium-activated potassium conductance or a transient potassium conductance under our recording conditions. Baclofen and GABA at 100 microM had no consistent effect on the voltage-activated potassium current. Baclofen did not change the resting potassium conductance.

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