title: A video-computer for the chronotropic and inotropic measurements of the beating of cultured heart cells.
abstract: A video-computer system has been developed to measure the chronotropy and inotropy of cultured heart cells. The motion of the cell is followed by recording of the changes of light intensity from the edge of a beating cell. With this system the velocity of contraction and relaxation, the time to peak contraction, relaxation time and the displacement of the cell in culture can be measured for the first time. Also, the rate of beating can be measured beyond the limits set by visual counting. With the application of this technique to the cultured heart cell system we have found that norepinephrine increases the velocity of relaxation thus reducing the ratio of contraction velocity to relaxation velocity, and reduces the twitch time. Increased external calcium, on the other hand, has little effect on either the velocity of contraction or relaxation but, like norepinephrine, decreases the twitch time.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002478:Cells, Cultured; D003201:Computers; D006339:Heart Rate / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats
chemical_list: D002118:Calcium; D009638:Norepinephrine