Nicotinic acetylcholine receptor is involved in acetylcholine regulating stomatal movement

In animal cells, actions of acetylcholine depend on its binding to specific receptors. Activation of nicotinic acetylcholine receptor can affect the m embrane permeability to ions directly. As concerned about acetylcholine reg ulating stomatal movement, nicotinic acetylcholine receptor may also be inv olved. Experiments with nicotinic acetylcholine receptor antagonist (D-tubo curarine) and agonist (nicotine) showed that nicotinic acetylcholine recept or was involved in acetylcholine inducing stomatal opening. In addition, th ese effects of D-tubocurarine and nicotine on stomatal movement can only be found in medium containing K+ while no effects can be found in medium cont aining Ca2+. The result by Western blotting showed that at least alpha- and beta-subunits of nicotinic receptor existed in microsomes of guard cell pr otoplasts. It was found that the distribution of nicotinic acetylcholine re ceptor was mainly on the surface of protoplasts as shown by FITC labelled a lpha-bungarotoxin. The results above show that nicotinic acetylcholine rece ptor exists in guard cells and mediates acetylchlone to induce stomatal ope ning.