期刊
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
卷 24, 期 10, 页码 -出版社
MDPI
DOI: 10.3390/ijms24108960
关键词
rat myocardium; right atrium; right ventricle; Frank-Starling mechanism; Ca2+ transient
The differences in contractility regulation and calcium handling between atrial and ventricular myocardium were poorly studied. This study found that the right atrial muscles were stiffer, faster, and weaker in active force compared to the right ventricular muscles. The length-dependent effects and passive/active force relationships were similar in both muscles.
The comparative differences in the fundamental mechanisms of contractility regulation and calcium handling of atrial and ventricular myocardium remain poorly studied. An isometric force-length protocol was performed for the entire range of preloads in isolated rat right atrial (RA) and ventricular (RV) trabeculae with simultaneous measurements of force (Frank-Starling mechanism) and Ca2+ transients (CaT). Differences were found between length-dependent effects in RA and RV muscles: (a) the RA muscles were stiffer, faster, and presented with weaker active force than the RV muscles throughout the preload range; (b) the active/passive force-length relationships were almost linear for the RA and RV muscles; (c) the value of the relative length-dependent growth of passive/active mechanical tension did not differ between the RA and RV muscles; (d) the time-to-peak and amplitude of CaT did not differ between the RA and RV muscles; (e) the CaT decay phase was essentially monotonic and almost independent of preload in the RA muscles, but not in the RV muscles. Higher peak tension, prolonged isometric twitch, and CaT in the RV muscle may be the result of higher Ca2+ buffering by myofilaments. The molecular mechanisms that constitute the Frank-Starling mechanism are common in the rat RA and RV myocardium.
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