期刊
FISH PHYSIOLOGY AND BIOCHEMISTRY
卷 47, 期 6, 页码 1969-1982出版社
SPRINGER
DOI: 10.1007/s10695-021-01023-7
关键词
Cardiac function; Facultative air-breathing fish; Force-frequency relationship; SERCA; NCX; PLN
资金
- FAPESP (Sao Paulo Research Foundation -N.U.J. Scientific Initiation Fellowship) [11/07645-1]
- CAPES (Coordination for the Improvement of Higher Education Personnel)
- INCT-FisComp (National Institute of Science and Technology in Comparative Physiology -Grant) [CNPq 573921/2008-3, FAPESP 08/57712-4]
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [11/07645-1] Funding Source: FAPESP
The study demonstrated that contraction is strongly regulated by extracellular Ca2+ and the ventricular tissue of African catfish is responsive to beta-adrenergic stimulation, improving cardiac pumping capacity. The expression patterns of NCX, SERCA, and PLN in African catfish myocardium indicate both mechanisms for Ca2+ transport contribute to Ca2+ activator.
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.
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