Abstract
A cholinergic receptor on outer hair cells (OHC) in guinea pig cochlea induces a K+ current when it is activated by acetylcholine and suberyldicholine but not by nicotine or muscarine (Bobbin, 1995). This unusual receptor may contain an α9-subunit. However, the pharmacology of the α9-subunit cloned from rat and expressed in Xenopus oocytes does not completely match that obtained for the ACh receptor in guinea pig OHCs. The response to 1,1-dimethyl-4-phenylpiperazinium (DMPP) is large in guinea pig OHCs and small in oocytes containing receptors of the α9-subunit. Therefore, we compared the effects of cholinergic receptor agonists in rat and guinea pig OHCs using the whole-cell variant of the patch-clamp technique. ACh caused the largest outward K+ current in OHCs from both rat and guinea pig. Carbachol- and suberyldicholine-induced responses were similar in magnitude in OHCs of rat and guinea pig. However, DMPP produced a small response in OHCs from rat and a large response in OHCs from guinea pig. At a concentration of 100 μM, muscarine, oxotremorine M, nicotine and cytisine induced little response in guinea pig OHCs and none in rat OHCs. Results suggest that the ACh receptor on rat OHCs is similar to the α9-subunit-containing receptor expressed in oocytes but different from the ACh receptor on guinea pig OHCs.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 9-17 |
| Number of pages | 9 |
| Journal | Hearing Research |
| Volume | 98 |
| Issue number | 1-2 |
| DOIs | |
| State | Published - Sep 1 1996 |
| Externally published | Yes |
Keywords
- Acetylcholine
- Cochlea
- Patch-clamp
- Receptor
- Voltage-clamp
ASJC Scopus subject areas
- Sensory Systems