( ( ( Ion ( ( channels and ) membrane ) ) excitability ) ; )
(ROOT (S (VP (VB Ion) (NP (NNS channels) (CC and) (NNS membrane)) (ADVP (RB excitability))) (: ;)))
Ion channels and membrane excitability;
(ROOT (NP (NP (NP (NNP Ion) (NNP channels) (NNP facilitate)) (PRN (-LRB- -LRB-) (PRP s) (-RRB- -RRB-))) (NP (NP (DT the) (NN diffusion)) (PP (IN of) (NP (NP (NNS ions)) (PP (IN across) (NP (DT a) (NN membrane)))))) (. .)))