Inotropic effect of hyperosmotic NaCl solutions on the isolated rat cardiac tissue. |
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Authors: | J W Bassani R A Bassani M Rocha-e-Silva |
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Institution: | Departamento de Engenharia Biomédica, Faculdade de Engenharia Elétrica, Universidade Estadual de Campinas, Brazil. |
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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). |
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