Collateral function is impaired in aged F344 × BN rats with aortic pathology

Abstract

Introduction: This study was performed to determine if hindlimb collateral function is impaired in a rat model which develops age-related vascular pathology similar to that observed in humans. Methods: Rats aged 6 (n = 6) and 24 (n = 6) months were studied. Under pentobarbital anesthesia, iliac artery blood flow was measured before and during occlusion of the femoral artery. The thoracic aorta, abdominal aorta, iliac arteries, and femoral arteries were harvested after perfusion fixation with paraformaldehyde and subsequently plastic embedded, sectioned, and stained. Results: Prior to occlusion, iliac flows were 3.0 ± 0.01 mL/min and 3.5 ± 0.02 mL/min respectively in 6 and 24 month old rats. After occlusion in the young rats, flow dropped initially by 0.8 ± 0.01 mL/min and then recovered by 0.7 ± 0.02 mL/min, essentially reaching pre-occlusion values. In 24 month old animals, flow decreased initially by 0.9 ± 0.01 mL/min but only recovered 0.4 ± 0.01 mL/min (p < 0.05). Intimal thickening was apparent only in the thoracic aorta of 24 month old animals. Conclusions: The increase in iliac artery blood flow after femoral artery occlusion reflects dilation of collateral vessels. The reduced compensation in older animals suggests that flow-dependent collateral dilation is reduced. This is consistent with studies which have demonstrated a progressive increase in endothelial dysfunction with aging. These observations together with the aortic pathology are consistent with the hypothesis that vascular aging not only promotes large vessel pathology, but also suppresses the capacity for compensation such as collateral dilation.