ACTIONS OF NEUROTRANSMITTERS AND OTHER MESSENGERS ON CA2-MUSCLE CELLS( CHANNELS AND K+ CHANNELS IN SMOOTH)

Ion channels play key roles in determining smooth muscle tone by setti ng the membrane potential and allowing Ca2+ influx. Perhaps not surpri singly, therefore, they also provide targets for neurotransmitters and other messengers that act on smooth muscle. Application of patch-clam p and molecular biology techniques and the use of selective pharmacolo gy has started to provide a wealth of information on the ion channel s ystems of smooth muscle cells, revealing complexity and functional sig nificance. Reviewed are the actions of messengers (e.g., noradrenaline , acetylcholine, endothelin, angiotensin II, neuropeptide Y, 5-hydroxy tryptamine, histamine, adenosine, calcitonin gene-related peptide, sub stance P, prostacyclin, nitric oxide and oxygen) on specific types of ion channel in smooth muscle, the L-type calcium channel, and the larg e conductance Ca2+-activated, ATP-sensitive, delayed rectifier and apa min-sensitive K+ channels. (C) 1997 Elsevier Science Inc.