Cardiac contractility of the African sharptooth catfish, Clarias gariepinus: role of extracellular Ca2+, sarcoplasmic reticulum, and beta-adrenergic stimulation

Autor(es)

Monteiro, Diana Amaral ^[1] ; Lopes, Andre Guelli ^{[1, 2]} ; Jejcic, Nathalia Usun ^[1] ; da Silva Vasconcelos, Eliton ^{[1, 2]} ; Kalinin, Ana Lucia ^[1] ; Rantin, Francisco Tadeu ^[1]

Afiliação do(s) autor(es)

^[1] Fed Univ Sao Carlos UFSCar, Dept Physiol Sci, Via Washington Luis Km 235, BR-13565905 Sao Carlos, SP - Brazil

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

• Tipo de documento: Artigo Científico
• Fonte: FISH PHYSIOLOGY AND BIOCHEMISTRY; v. 47, n. 6 OCT 2021.
• Citações Web of Science: 0

Resumo

This study investigated the dependence of contraction from extracellular Ca2+, the presence of a functional sarcoplasmic reticulum (SR), and the effects of beta-adrenergic stimulation using isometric cardiac muscle preparations. Moreover, the expression of Ca2+-handling proteins such as SR-Ca2+-ATPase (SERCA), phospholamban (PLN), and Na+/Ca2+ exchanger (NCX) were also evaluated in the ventricular tissue of adult African sharptooth catfish, Clarias gariepinus, a facultative air-breathing fish. In summary, we observed that (1) contractility was strongly regulated by extracellular Ca2+; (2) inhibition of SR Ca2+-release by application of ryanodine reduced steady-state force production; (3) ventricular myocardium exhibited clear post-rest decay, even in the presence of ryanodine, indicating a decrease in SR Ca2+ content and NCX as the main pathway for Ca2+ extrusion; (4) a positive force-frequency relationship was observed above 60 bpm (1.0 Hz); (5) ventricular tissue was responsive to beta-adrenergic stimulation, which caused significant increases in twitch force, kept a linear force-frequency relationship from 12 to 96 bpm (0.2 to Hz), and improved the cardiac pumping capacity (CPC); and (6) African catfish myocardium exhibited similar expression patterns of NCX, SERCA, and PLN, corroborating our findings that both mechanisms for Ca2+ transport across the SR and sarcolemma contribute to Ca2+ activator. In conclusion, this fish species displays great physiological plasticity of E-C coupling, able to improve the ability to maintain cardiac performance under physiological conditions to ecological and/or adverse environmental conditions, such as hypoxic air-breathing activity. (AU)

• Processo FAPESP: 08/57712-4 - Instituto Nacional de Pesquisas em Fisiologia Comparada
• Beneficiário: Augusto Shinya Abe
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 11/07645-1 - Função cardíaca in vitro do bagre africano Clarias gariepinus
• Beneficiário: Nathalia Usun Jejcic
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica