title: Nonsteady motion in unloaded contractions of single frog cardiac cells.
abstract: We studied the mode of shortening of enzymatically isolated single frog cardiac cells with a high-speed videosystem to see whether or not shortening is smooth. The segmental shortening of the cell in response to electrical stimulation exhibited a clear pause following the initial shortening over a distance of approximately 11 nm/half-sarcomere. Several preparations showed a second pause following the initial one. Nonsteady motion with a pause lasted usually a few tens of milliseconds. The duration of nonsteady motion was shorter in cells with large velocities of steady shortening following the pause than those with smaller velocities.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002465:Cell Movement; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D009200:Myocardial Contraction / Q000187:drug effects; D009206:Myocardium / Q000166:cytology; D011892:Rana catesbeiana; D016276:Ventricular Function
chemical_list: D002118:Calcium