Effect of heart failure on catecholamine granule morphology and storage in chromaffin cells

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Cell Biology

Background:

• Sympathoexcitation is a hallmark of chronic heart failure (HF).
• Adrenal gland activation and elevated circulating catecholamines contribute to HF pathophysiology.
• The specific in vivo structural and metabolic adaptations of adrenomedullary chromaffin cells in HF remain largely uncharacterized.

Purpose of the Study:

• To investigate the in vivo structural and metabolic changes in adrenal chromaffin cells in a rat model of chronic heart failure.
• To elucidate the relationship between sympathoexcitation, adrenal gland overactivation, and catecholamine production in HF.

Main Methods:

• Chronic heart failure (HF) was induced in male Sprague-Dawley rats via left coronary artery ligation.
• Cardiac function was assessed using ventricular hemodynamics five weeks post-surgery.
• Adrenal glands were examined for structural alterations, catecholamine levels, and cellular organelle morphology in HF versus sham-operated rats.

Main Results:

• HF rats exhibited increased adrenal weight and elevated levels of norepinephrine, epinephrine, and dopamine compared to controls.
• Ultrastructural analysis revealed increased synaptic vesicles, endoplasmic reticulum, Golgi apparatus, and mitochondria with dilated cristae and glycogen in chromaffin cells of HF rats.
• These morphological changes suggest enhanced trans-synaptic activation and increased capacity for catecholamine synthesis and release.

Conclusions:

• Chronic heart failure induces significant structural and metabolic adaptations in adrenal chromaffin cells to support heightened catecholamine production.
• These cellular adaptations provide a mechanistic link between HF, adrenal overactivation, and elevated plasma catecholamines.
• The findings offer novel insights into the neurohumoral mechanisms driving cardiovascular dysfunction in chronic heart failure.