Key result
Western diet-induced obesity impairs LA cardiomyocyte contractility via slowed cross-bridge cycling and cMyBP-C dephosphorylation.
Why the study?
Obesity is a major risk factor for heart failure and atrial fibrillation, prompting investigation into the effects of diet-induced obesity on molecular and cellular mechanisms of atrial cardiomyocyte contractility.
Does an 18-week Western diet impair left and right atrial cardiomyocyte contractility in female Wistar rats?
Does an 18-week Western diet impair left and right atrial cardiomyocyte contractility in female Wistar rats?
An 18-week Western diet in female rats induces early-stage contractile impairment specific to the left atrium, driven by slowed cross-bridge cycling and cMyBP-C dephosphorylation, preceding overt cardiac remodeling.
Hypothesis-generating for early left atrial myopathy in obesity; clinical translation requires prospective human studies.
Obesity is a major risk factor for heart failure and atrial fibrillation. This study investigated the effects of diet-induced obesity on the molecular and cellular mechanisms of cardiomyocyte contractility in the left and right atria (LA and RA). Female Wistar rats were fed a Western diet (WD) for 18 weeks. Sarcomere dynamics and calcium transients were measured in unloaded cardiomyocytes. Actin–myosin interactions and contractile protein phosphorylation were assessed via an in vitro motility assay and phosphoprotein-specific gel electrophoresis. WD-fed rats developed obesity, hypertension, and metabolic alterations in the absence of echocardiographic or histological evidence of cardiac remodeling or systolic dysfunction. In LA cardiomyocytes, contractile dysfunction was indicated by increased calcium transient amplitude coupled with reduced shortening amplitude and relengthening velocity. This functional impairment correlated with a slowed myosin cross-bridge cycle and dephosphorylation of cMyBP-C. In contrast, RA cardiomyocytes displayed only molecular changes in response to obesity, including altered phosphorylation of most sarcomeric proteins and a decelerated cross-bridge cycle, but showed no evident contractile dysfunction. Thus, an 18-week WD reflects the early stages of contractile impairment, where functional deficits are specific to the LA, while RA alterations are confined to the molecular level.
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Mukhlynina et al. (2026) studied Diet-induced obesity. Western diet was evaluated on Cardiomyocyte contractility, sarcomere dynamics, and calcium transients in the left and right atria. An 18-week Western diet in female Wistar rats induced left atrial contractile dysfunction associated with a slowed myosin cross-bridge cycle and dephosphorylation of cMyBP-C.
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