Voltage-gated currents in rabbit retinal astrocytes.
The voltage-gated currents of the astrocytes associated with the retinal capillaries of the rabbit retina were studied using whole-cell patch clamp recording. The resting potential of these cells was -70 +/- 4.8 mV (mean +/- SEM; n = 54), and the input resistance and cell capacitance were 558 +/- 3.6 M omega and 19.5 +/- 1.8 pF respectively. Depolarization to potentials positive to -50 mV evoked rapidly activating inward and outward currents. The inward current was transient, eliminated by substitution of choline for Na+ in the bathing solution, and reduced by 50% in the presence of 1 microM tetrodotoxin. The time-to-peak of the Na+ current was more than twice that for the Na+ current found in retinal neurons. The glial Na+ current was half-inactivated at -55 mV. A transient component of the outward K+ current was blocked by external 4-aminopyridine while a more sustained component was blocked by external tetraethylammonium. At potentials between -150 and -50 mV the membrane behaved Ohmically. Voltage-gated currents in retinal astrocytes recorded in situ appear qualitatively similar to those described for some glial cells in vitro.
Clark
B A
BA
Department of Physiology, University College London, UK.
Mobbs
P
P
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology*; D002794:Choline / Q000494:pharmacology; D004553:Electric Conductivity; D004594:Electrophysiology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D026902:Potassium Channel Blockers; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D026902:Potassium Channel Blockers; D013757:Tetraethylammonium Compounds; D013779:Tetrodotoxin; D019789:Tetraethylammonium; D015761:4-Aminopyridine; D002794:Choline