Inotropic effect of hyperosmotic NaCl solutions on the isolated rat cardiac tissue.
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).
Bassani
J W
JW
Departamento de Engenharia Biomédica, Faculdade de Engenharia Elétrica, Universidade Estadual de Campinas, Brazil.
Bassani
R A
RA
Rocha-e-Silva
M
M
D000818:Animals; D016275:Atrial Function; D003864:Depression, Chemical; D007700:Kinetics; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D012462:Saline Solution, Hypertonic / Q000494:pharmacology*; D012996:Solutions; D013268:Stimulation, Chemical; D013395:Sucrose / Q000008:administration & dosage / Q000494:pharmacology
D012462:Saline Solution, Hypertonic; D012996:Solutions; D013395:Sucrose