We recently reported that non-secretory gastrointestinal smooth muscle cells also possessed SNARE proteins, of which SNAP-25 regulated Ca2+-activated (K-Ca) and delayed rectifier K+ channels (K-V). Voltage-gated, long lasting (L-type) calcium channels (L-Ca) play an important role in excitation-con traction coupling of smooth muscle. Here, we show that SNAP-25 could also directly inhibit the L-type Ca2+ channels in feline esophageal smooth muscle cells at the SNARE complex binding synprint site. SNARE proteins could therefore regulate additional cell actions other than membrane fusion and secretion, in particular, coordinated muscle membrane excitability and contraction, through their actions on membrane Ca2+ and K+ channels. (C) 2003 Elsevier Science (USA). All rights reserved.