Abstract
Adiponectin is the most abundant plasma adipokine, and is well known for its role in energy homeostasis and cardiac protection. In humans with dilated cardiomyopathy, myocardial adiponectin protein expression is reduced compared to normal hearts and has been implicated in the pathology of cardiomyopathy. Serum adiponectin levels are often conflicting, with higher levels associated with poor survival in humans with congestive heart failure (CHF). We evaluated adiponectin serum concentrations and myocardial protein expression in dogs with naturally occurring myxomatous mitral valve disease and CHF. We compared the findings to active and hibernating brown bears as bears are adapted to endure an extreme period of low cardiac output during their annual hibernation. Bears exhibited largely the active high-molecular weight (HMW) versus the low-molecular weight isoforms of myocardial adiponectin (HMW:LMW = 6.3) during both the active period and hibernation, while healthy dogs exhibited a more balanced mix of isoforms. Dogs with CHF expressed predominately HMW isoforms of adiponectin (HMW:LMW = 12.5), appearing more similar to bears. In contrast to humans, serum adiponectin was significantly lower in dogs with CHF and lowest levels in the severest CHF class. In both dogs and bears, myocardial adiponectin was expressed independent of circulating adiponectin concentrations, suggesting a local regulatory mechanism within the heart.
Highlights
Adiponectin is a primarily adipose tissue-derived cytokine that plays a key role in both metabolic and cardiac health
Mean serum adiponectin concentration was significantly higher in healthy dogs
The congestive heart failure (CHF) dogs mirrored the bears’ myocardial adiponectin expression, as bears exhibited a predominance of high-molecular weight (HMW) adiponectin in both the active and hibernating seasons (Figures 4 and 5)
Summary
Adiponectin is a primarily adipose tissue-derived cytokine that plays a key role in both metabolic and cardiac health. Along with the knowledge of adiponectin’s reputed beneficial effects on the heart, this U-shaped relationship of serum adiponectin in cardiac disease has been designated as “the adiponectin paradox” [34,35]. It is unclear if adiponectin has a negative impact on cardiac pathophysiology or if levels may rise to mitigate robust neurohormonal and metabolic impairment in CHF. Hibernation is a natural physiological condition, and cardiovascular compensatory adaptations must occur for the myocardium to remain healthy and efficient during a long period of extremely low cardiac output. Comparing a natural bradycardic state in bears that would create cardiac failure in other animals to a pathologic cardiac state in dogs may highlight adaptive processes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
