Calcium-osmolality interaction in the inotropic response of isolated rat atria to increased sodium concentration.
The effects of osmolality (300 and 450 mOsm/l) and external calcium concentration ([Ca2+]o: 0.87, 1.13, 1.47 and 1.92 mM) on the inotropic response of isolated rat left atria to an increase of 97.8 mM in extracellular sodium concentration ([Na+]o) were studied. The evoked tensions developed during 30 min after the exposure to increased [Na+]o increased with increasing [Ca2+]o. In iso-osmotic solutions, tension was lower than in hyperosmotic solutions when [Ca2+]o was 0.87 and 1.13 mM, but not for higher [Ca2+]o, revealing a Ca2(+)-osmolality interaction in the determination of the inotropic response.
Bassani
J W
JW
Departamento de Engenharia Biomédica, Faculdade de Engenharia Elétrica, Universidade Estadual de Campinas, SP, Brasil.
Bassani
R A
RA
D000818:Animals; D016275:Atrial Function; D002118:Calcium / Q000378:metabolism*; D008297:Male; D009200:Myocardial Contraction; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*
D012964:Sodium; D002118:Calcium