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

Author(s)

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]

Affiliation

^[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

• Document type: Journal article
• Source: FISH PHYSIOLOGY AND BIOCHEMISTRY; v. 47, n. 6 OCT 2021.
• Web of Science Citations: 0

Abstract

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)

• FAPESP's process: 08/57712-4 - The National Institute of Comparative Physiological Research
• Grantee: Augusto Shinya Abe
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 11/07645-1 - In vitro cardiac function of the African catfish Clarias gariepinus
• Grantee: Nathalia Usun Jejcic
• Support Opportunities: Scholarships in Brazil - Scientific Initiation