Lower skeletal muscle capillarization in hypertensive elderly men.

Area of Science:

• Gerontology
• Vascular Biology
• Skeletal Muscle Physiology

Background:

• Aging is associated with skeletal muscle microvascular dysfunction and is a primary risk factor for metabolic syndrome.
• Hypertension, a common component of metabolic syndrome in the elderly, significantly impacts vascular alterations.
• The effects of hypertension and metabolic syndrome on skeletal muscle capillarization during aging remain poorly understood.

Purpose of the Study:

• To investigate the impact of hypertension and metabolic syndrome on skeletal muscle capillarization in elderly men.
• To compare capillarization parameters between normotensive young and elderly men, and elderly men with hypertension or metabolic syndrome.
• To examine the relationship between capillarization, extracellular matrix (ECM) composition, and mitochondrial oxidative capacity (cytochrome c oxidase - COX) in aged skeletal muscle.

Main Methods:

• Muscle biopsies were obtained from normotensive young (YO), elderly control (ELc), elderly hypertensive (EL-HT), and elderly metabolic syndrome (EL-MS) men.
• Capillarization was assessed by measuring capillaries around a fiber (CAF), capillary-to-fiber perimeter exchange (CFPE), length of contact to perimeter of fiber ratio (LC/PF), and capillary tortuosity.
• Extracellular matrix (ECM) embedding capillaries and cytochrome c oxidase (COX) content were also analyzed.

Main Results:

• Capillarization and COX content did not differ between young and elderly normotensive individuals.
• Elderly men with hypertension exhibited significantly reduced CAF, CFPE, LC/PF, and capillary tortuosity compared to elderly controls.
• Hypertension was associated with increased ECM endomysium fibrosis and lower COX content in aged skeletal muscle; metabolic syndrome showed no additional impact.

Conclusions:

• Hypertension plays a critical role in age-related skeletal muscle capillarization decline.
• Reduced capillarization in hypertensive elderly men is linked to impaired mitochondrial oxidative capacity.
• Other components of metabolic syndrome do not appear to significantly alter the aged skeletal muscle capillary network beyond the effects of hypertension.