Effect of acute temperature transitions on chronotropic and inotropic responses of the South American lungfish Lepidosiren paradoxa |
| |
| Institution: | 1. Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, CEP 13565-905, Brazil;2. Department of Biological Sciences, Developmental Integrative Biology Cluster, University of North Texas, Denton, TX 76203-5220, USA;1. Department of Biology, McMaster University, Hamilton, ON, Canada;2. Developmental Integrative Biology, Department of Biological Sciences, University of North Texas, Denton, TX, USA |
| |
| Abstract: | The in vivo and in vitro cardiac responses of Lepidosiren paradoxa were analyzed during temperature variations from 25°C (acclimation temperature) to 15°C and 35°C, and subsequent return to 25°C. Chronotropic (heart frequency) and inotropic (twitch force) responses varied directly with temperature, decreasing from 25°C to 15°C and increasing from 25°C to 35°C. However, time to peak tension (TPT) and time to half relaxation (THR) showed an inverse tendency. The results indicate that the myocardium of L. paradoxa responds more appropriately to acute elevations in temperature, which results in an increased cardiac performance due to both positive chronotropism and inotropism, in spite of the temperature-induced curtailment of TPT and THR. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
