| Title: |
Expression and characterization of a canine hippocampal inwardly rectifying K+ current in Xenopus oocytes. |
| Authors: |
Cui, J; Mandel, G; DiFrancesco, D; Kline, R P; Pennefather, P; Datyner, N B; Haspel, H C; Cohen, I S |
| Source: |
The Journal of Physiology ; volume 457, issue 1, page 229-246 ; ISSN 0022-3751 1469-7793 |
| Publisher Information: |
Wiley |
| Publication Year: |
1992 |
| Collection: |
Wiley Online Library (Open Access Articles via Crossref) |
| Description: |
1. An inwardly rectifying potassium current expressed in Xenopus laevis oocytes injected with canine hippocampal poly(A)+ RNA was investigated with the two‐microelectrode voltage clamp technique. 2. Xenopus oocytes injected with canine hippocampal poly(A)+ RNA expressed a current activated by hyperpolarization. This current contained an instantaneous and a time‐dependent component. Both components were inwardly rectifying and could be blocked by extracellular Cs+ or Ba2+. 3. The expressed current was carried mainly by K+. Its reversal potential measured in different [K+]os could be fitted by the Nernst equation with a slope of ‐50.7 per tenfold change in [K+]o. Extracellular Cl‐ and Na+ made minimal contributions to the current. 4. The activation of the expressed current depended on both voltage and [K+]o. Activation started near EK and the activation curve shifted along the voltage axis in parallel with EK when [K+]o was altered. 5. The activation time constants of the expressed current also depended on both voltage and [K+]o. The voltage dependence of the time constants was bell‐shaped and the peak value was at a potential 30‐50 mV more negative than EK. The voltage dependence of the time constants shifted along the voltage axis when EK was changed. 6. The poly(A)+ RNA extracted from canine hippocampus was fractionated in a 10‐31% linear sucrose gradient. The size of the mRNA required to express the inwardly rectifying current was estimated to be around 4 kb. 7. In conclusion, the expressed current is an inwardly rectifying potassium current. The canine hippocampal mRNA should be an excellent source for expression‐cloning of the inward rectifier channel. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| DOI: |
10.1113/jphysiol.1992.sp019375 |
| Availability: |
https://doi.org/10.1113/jphysiol.1992.sp019375; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1113%2Fjphysiol.1992.sp019375; https://physoc.onlinelibrary.wiley.com/doi/pdf/10.1113/jphysiol.1992.sp019375 |
| Rights: |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
| Accession Number: |
edsbas.214C146B |
| Database: |
BASE |