Two Types of Voltage-activated Calcium Currents in Goldfish Horizontal Cells.
- Author:
Sun Sook PAIK
1
;
Sun Ho BAI
;
Chang Sub JUNG
Author Information
1. Department of Physics & Biophysics, College of Medicine, The Catholic University of Korea, Seoul 137-701, Korea. cjung@catholic.ac.kr
- Publication Type:Original Article
- Keywords:
Horizontal cell;
Sustained calcium current;
Transient calcium current;
Goldfish;
Whole-cell Patch-Clamp;
Retina
- MeSH:
Calcium*;
Goldfish*;
Hand;
Nifedipine;
Retina;
Sensitivity and Specificity
- From:The Korean Journal of Physiology and Pharmacology
2005;9(5):269-273
- CountryRepublic of Korea
- Language:English
-
Abstract:
In horizontal cells (HCs) that were freshly dissociated from goldfish retina, two types of voltage- dependent calcium currents (ICa) were recorded using a patch-clamping configuration: a transient type current and a sustained type current. The cell was held at -40 mV, and the prepulse step of -90 mV was applied before command pulse between -65 and +55 mV. The transient Ca2+ current was activated by depolarization to around -50 mV from a prepulse voltage of -90 mV lasting at least 400 ms and reached a maximal value near -25 mV. On the other hand, the sustained Ca2+ current was induced by pre-inactivation for less than 10 ms duration. Its activation started near -10 mV and peaked at +20 mV. Co2+ (2 mM) suppressed both of these two components, but nifedipine (20microM), L-type Ca2+ channel antagonist, blocked only the sustained current. Based on the activation voltage and the pharmacological specificity, the sustained current appears to be similar to L-type ICa and the transient type to T-type ICa. This study is the first to confirm that transient type ICa together with the sustained one is present in HCs dissociated from goldfish retina.
