Effects of change in temperature on the cardiac contractility of broad-snouted caiman (Caiman latirostris) during digestion

Autor(es)

Lopes, Andre G. ^{[1, 2]} ; Monteiro, Diana A. ^[1] ; Kalinin, Ana L. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, Dept Physiol Sci, Sao Carlos, SP - Brazil

^[2] Fed Univ Sao Carlos UFSCar Sao Paulo State Univ, Joint Grad Program Physiol Sci, UNESP Campus Araraquara, Araraquara, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY; v. 335, n. 4 MAR 2021.
• Citações Web of Science: 0

Resumo

In many reptiles, digestion has been associated with the selection of higher body temperatures, the so-called post-prandial thermophilic response. This study aimed to investigate the excitation-contraction (E-C) coupling in postprandial broad-snouted caimans (Caiman latirostris) in response to acute warming within a preferred body temperature range of crocodiles. Isometric preparations subjected to a temperature transition from 25 degrees C to 30 degrees C were used to investigate myocardial contractility of postprandial caimans, that is, 48 h after the animals ingested a rodent meal corresponding to 15% of body mass. The caiman heart exhibits a negative force-frequency relationship that is independent of the temperature. At 25 degrees C, cardiac muscle was able to maintain a constant force up to 36 bpm, above which it decreased significantly, reaching minimum values at the highest frequency of 84 bpm. Moreover, E-C coupling is predominantly dependent on transsarcolemmal Ca2+ transport denoted by the lack of significant ryanodine effects on force generation. On the contrary, ventricular strips at 30 degrees C were able to sustain the cardiac contractility at higher pacing frequencies (from 12 to 144 bpm) due to an important role of Na+/Ca2+ exchanger in Ca2+ cycling, as indicated by the decay of the post-rest contraction, and a significant contribution of the sarcoplasmic reticulum above 72 bpm. Our results demonstrated that the myocardium of postprandial caimans exhibits a significant degree of thermal plasticity of E-C coupling during acute warming. Therefore, myocardial contractility can be maximized when postprandial broad-snouted caimans select higher body temperatures (preferred temperature zone) following feeding. (AU)

• Processo FAPESP: 08/57712-4 - Instituto Nacional de Pesquisas em Fisiologia Comparada
• Beneficiário: Augusto Shinya Abe
• Modalidade de apoio: Auxílio à Pesquisa - Temático