Ionic currents of smooth muscle cells isolated from the ctenophore Mnemiopsis.
The ionic currents of smooth muscle cells isolated from the ctenophore Mnemiopsis were examined by using conventional two-electrode voltage clamp and whole-cell patch clamping methods. Several separable currents were identified. These include: (1) a transient and (2) a steady-state voltage-activated inward current; both are tetrodotoxin (TTX) and saxitoxin (STX) insensitive, partly reduced by decreasing external Ca2+ or Na+ or by addition of 5 mM Co2+, D-600 or verapamil and are totally blocked with 5 mM Cd2+; (3) an early, transient, cation-dependent, outward K+ current (IKCa/Na); (4) a transient, voltage-activated, outward K+ current provisionally identified as IA; (5) a delayed, steady-state, voltage-activated outward K+ current (IK) and (6) a late, transient, outward K+ current which is blocked by Cd2+ and evident only during long voltage pulses. Despite their phylogenic origin, most of these currents are similar to currents identified in many vertebrate smooth and cardiac muscle preparations, and other excitable cells in higher animals.
Dubas
F
F
Whitney Laboratory, University of Florida, St Augustine 32086.
Stein
P G
PG
Anderson
P A
PA
D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D003063:Cnidaria / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism*; D009130:Muscle, Smooth / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D007473:Ion Channels; D012964:Sodium; D011188:Potassium; D002118:Calcium