L-arginase induces vascular dysfunction in old spontaneously hypertensive rats

Area of Science:

• Vascular Biology
• Aging Research
• Hypertension

Background:

• Aging is a significant risk factor for hypertension, sharing similarities with vascular changes seen in hypertensive conditions.
• Arginase activity reduces L-arginine availability, decreasing nitric oxide (NO) production, leading to impaired vasodilation and vascular dysfunction.

Purpose of the Study:

• To investigate the hypothesis that arginase mediates age-dependent vascular dysfunction in spontaneously hypertensive rats (SHRs).

Main Methods:

• Compared young and old Wistar and SHR rats, measuring mean arterial pressure (MAP).
• Assessed vascular reactivity in mesenteric resistance arteries (MRAs) and thoracic aortae using acetylcholine (Ach) and sodium nitroprusside (SNP) in the presence or absence of L-arginase.

Main Results:

• MAP increased with age in SHRs but not Wistar rats.
• Arginase significantly impaired endothelium-dependent relaxation to Ach in old Wistar and SHR vessels.
• Arginase also impaired endothelium-independent relaxation to SNP in old SHRs.

Conclusions:

• Arginase negatively impacts both endothelium-dependent and -independent vasorelaxation.
• These effects are mediated through the nitric oxide (NO) signaling pathway, implicating arginase in age-related vascular dysfunction.