title: Cardiac tissue function of the teleost fish Oreochromis niloticus under different thermal conditions.
abstract: The cardiac responses of Oreochromis niloticus acclimated to 25 degrees C were assessed using ventricle strips mounted for isometric force recording (Fc) and in vivo heart rate (f(H)). f(H) increased progressively from 25 to 40 degrees C. At extracellular Ca(2+) concentrations of 1.25 and 9.25 mM, a transition from 25 to 40 degrees C resulted in a decreased Fc. At both 25 and 40 degrees C, Fc rose when [Ca(2+)] was increased from 1.25 to 9.25 mM. Fc remained constant at 72 and 120 contractions.min(-1) at 25 and 40 degrees C, respectively, and declined thereafter. The post-rest potentiation was not influenced by ryanodine, indicating that the sarcoplasmic reticulum is not important to the excitation-contraction coupling.
authors.affiliation: Department of Physiological Sciences, Federal University of São Carlos, Via Washington Luiz, km 235-13565-905, SP, São Carlos, Brazil
authors.initials: MJ
authors.lastname: Costa
authors.initials: L
authors.lastname: Rivaroli
authors.initials: FT
authors.lastname: Rantin
authors.initials: AL
authors.lastname: Kalinin