Electrical Activity in Single Myocardial Cells of Limulus polyphemus.
Single cells of the heart of Limulus were examined in situ with conventional microelectrodes. Resting and action potentials were measured in a total of 20 animals, with 25 penetrations per heart during normal spontaneous activity. Resting-potential values averaged 45 millivolts. Action potentials showed a rapid upstroke and a prolonged plateau. A small, irregular burst of electrical activity occurred during the plateau phase, a discharge presumably associated with the "neurogenic" character of the heartbeat. There was no significant overshoot, nor was there any topographical localization of action-potential "types.".
McCann
F V
FV