Related Experiment Video
Updated: Jul 17, 2026

Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice
Published on: September 17, 2015
Effect of calmodulin inhibitors on rat and guinea pig myocardial contractility
B I Laptev1, V D Prokopieva, S A Afanasiev
1Institute of Cardiology, Tomsky Research Center, USSR Academy of Medical Sciences.
Abstract:
The effects of phenothiazine drugs with different affinities for calmodulin (trifluoperazine, frenolone, majeptile and aminazine) on the contractility of rat and guinea pig papillary muscles were studied. The phenothiazine-induced changes in the contraction-relaxation parameters were shown to correlate with the degree of calmodulin inhibition. These parameters are relaxation-onset index, relaxation index and terminal relaxation index in rats, and relaxation index and maximal developed tension in guinea pigs. An essential role of calmodulin in myocardium relaxation in both animal species is postulated.
Related Concept Videos
Calmodulin-dependent Signaling
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
Antihypertensive Drugs: Action of Calcium Channel Blockers
Heart Failure Drugs: Inotropic Agents
Antianginal Drugs: Calcium Channel Blockers and Ranolazine
CCBs, a diverse class that includes dihydropyridines (nifedipine) and diphenylalkylamines (verapamil and diltiazem), exert their effect by blocking calcium channels in cardiac and smooth muscle cells. This...

