Related Experiment Video
Updated: Aug 7, 2026

Contractility Measurements on Isolated Papillary Muscles for the Investigation of Cardiac Inotropy in Mice
Published on: September 17, 2015
Inotropic effect of hyperosmotic NaCl solutions on the isolated rat cardiac tissue
J W Bassani1, R A Bassani, M Rocha-e-Silva
1Departamento de Engenharia Biomédica, Faculdade de Engenharia Elétrica, Universidade Estadual de Campinas, Brazil.
Abstract:
The inotropic effect of Krebs-Henseleit solution rendered hyperosmotic by addition of NaCl or sucrose (increments of 50, 100, 150 and 200 mOsm/l) on myocardial contractile activity was studied in rat isolated left atria paced at 4, 16 and 64 stim/min. The solutions did not affect the peak tension (Tp) at 4 stim/min, whereas sucrose caused a dose-dependent increase in Tp at 16 stim/min and NaCl decreased Tp at 64 stim/min. The total time duration of the contraction was increased in a dose-dependent fashion by both solutes, but the effect of NaCl was attenuated at 64 stim/min. The results showed that, in the isolated rat atrial tissue exposed to hyperosmotic NaCl solutions, the negative inotropic effect of increased Na+ concentration overcomes the positive influence of hyperosmolality only at higher pacing rates (about 1 Hz).
Related Concept Videos
Tonicity in Animals
Heart Failure Drugs: Inotropic Agents
Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials

