“…1967). Since then, i.j.p.s have been recorded in many different tissues in response to stimulation of extrinsic parasympathetic or intramural nerves (see Burnstock 1975b). The presence of non-adrenergic, non-cholinergic nerves has thus been established throughout the gastrointestinal tract of many vertebrate species (Burnstock, Campbell & Rand, 1966;Campbell & Burnstock, 1968) as well as in other organs including lung, urinary bladder, trachea, oesophagus, anococcygeus, seminal vesicles and parts of the cardiovascular system (see Burnstock, 1969Burnstock, , 1979bFurness & Costa, 1973).…”