Angiotensin II-induced inhibition and facilitation of calcium current subtypes in rat retinal ganglion cells.
Whole cell patch-clamp recordings were performed on freshly dissociated rat retinal ganglion cells to determine the action of Angiotensin II (AngII) on voltage-activated calcium current subtypes in this cell type. AngII had no effect on a toxin-resistant calcium current component; N-type currents were reduced by 27 +/- 5% in all retinal ganglion cells (RGCs) tested; L-type currents were reduced by 33 +/- 7% in 59% of the RGCs but increased by 31 +/- 6% in 41% of the cells. AngII effects were reversible within a few seconds through reperfusion with bath solution and calcium current kinetics and current-voltage relations remained unaffected. The net effect of AngII in a single RGC is either a reduction or an enhancement of the total calcium current, dependent on (1) the number of L-type channels compared to N-type channels and (2) on the kind of action AngII exerts on L-type channels.
Guenther
E
E
Department of Pathophysiology of Vision and Neuro-Ophthalmology, University Eye Hospital Tübingen, Germany. elke.guenther@uni-tuebingen.de
Hewig
B
B
Zrenner
E
E
Kohler
K
K
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D012165:Retinal Ganglion Cells / Q000737:chemistry / Q000187:drug effects* / Q000502:physiology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D015220:Calcium Channels; D018377:Neurotransmitter Agents; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D002118:Calcium