title: The relationship between extracellular calcium and isovolumic systolic pressure in the Langendorff-perfused rat heart.
abstract: The relationship between extracellular calcium concentration and isovolumic systolic pressure developed by left ventricles was studied in Langendorff-perfused rat hearts. At diastolic pressure lower than 15 mmHg the isovolumic systolic pressure increased when external calcium was changed from 0.5 to 1.25 mM. Pressure stabilized when external calcium was increased to 3.5 mM but then declined at 5 mM Ca2+. At higher diastolic pressures (20 and 25 mmHg) systolic pressure increased only up to 1.25 mM Ca2+, and declined with further increases in external calcium concentration. This behavior is probably related to "calcium overload" of the preparations at external calcium concentrations greater than 3.5 mM associated with a decreased perfusion pressure gradient at higher diastolic pressures.
authors.affiliation: Departamento de Ciências Fisiológicas, Universidade Federal do Espírito Santo, Vitória, Brasil.
authors.forename: I
authors.initials: I
authors.lastname: Stefanon
authors.forename: D V
authors.initials: DV
authors.lastname: Vassallo
authors.forename: J G
authors.initials: JG
authors.lastname: Mill
authors.forename: P F
authors.initials: PF
authors.lastname: Abaurre
authors.forename: R A
authors.initials: RA
authors.lastname: Pelloso
mesh_terms: D000818:Animals; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism*; D005260:Female; D008297:Male; D009200:Myocardial Contraction; D051381:Rats; D011919:Rats, Inbred Strains; D016276:Ventricular Function
chemical_list: D002118:Calcium