STABLE EXPRESSION IN HEK-293 CELLS OF THE RAT ALPHA-3 BETA SUBTYPE OFNEURONAL NICOTINIC ACETYLCHOLINE-RECEPTOR/

The alpha 3/beta 4 subtype of neuronal nicotinic acetylcholine recepto r (nAChR) was stably expressed in human embryonic kidney (HEK) 293 cel ls that co-expressed a voltage-gated Ca2+ channel. alpha 3/beta 4-nACh R-expressing clones were identified using the fura-2 Ca2+ imaging tech nique, and were further characterised by single-cell and whole-cell pa tch-clamp studies. Acetylcholine (ACh) induced fast activating current s which showed desensitisation and inward rectification. The conductan ce of the ACh-activated channel was 29 pS. The order of potency of the nicotinic agonists tested was cytisine congruent to nicotine > acetyl choline. The EC(50) value for ACh was 145 mu M; the Hill coefficient w as close to 2. The currents elicited by ACh were effectively blocked b y nicotinic antagonists, but not by the muscarinic antagonist atropine . These properties are comparable to the pharmacological and physiolog ical profile of ganglionic nicotinic receptors and type III currents o f cultured hippocampal neurons.