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Background:

Diabetes is a pervasive disease that can affect all organs and tissues of the body.  Hyperinsulinemia, hyperglycemia, dyslipidemia and advanced glycation end products are but a few of the anomalies of diabetes that impinge upon the vasculature and are causal agents for vascular inflammation and atherosclerosis. The purpose of this study was to determine the effects of age, obesity and hyperinsulinemia on carotid arteries after mechanical injury and compare the parameters of intima media thickness, lumen diameter and blood flow velocity between 8-week and 16-week, control (CON)(lean) and experiment (EXP)(fat) litter-mate male Zucker Diabetic Fatty rats.

Methods:

The injured carotid arteries of 8-week and 16-week old male Zucker Diabetic Fatty rats and their CON littermates were catheterized for endarterectomy at Charles River Laboratories. Rats were transported to our vivarium one week after endarterectomies were completed.  Using ultrasound imaging, internal lumen diameter, dorsal and ventral walls, external artery diameter and blood flow velocity of the injured carotid arteries (injured) were compared to the same parameters in the non-injured carotid arteries (internal non-injured) within the same age group, between CON and EXP rats of the same age group and between 8-week and 16-week age groups.   One week after receiving the rats, each rat was anesthetized for 30 minutes for ultrasound measurements using an isoflurane-oxygen solution.  Ultrasound images were collected on injured catheterized and non-injured CON carotid arteries on days 14, 21, 42 and 62 post surgery.

Results:

As age progressed, there were significant differences in the injured carotid lumen and injured total diameter measurements between the 8- and 16-week cohorts over time in CON and EXP rats.  We noted that the injured carotid arteries of the 8-week cohorts never improved, while the same parameters of the 16-week cohorts did exhibit recovery.  Interestingly, the 8-week rats demonstrated no change of the injured lumen over time after damage, while the 16-week rats demonstrated increased lumenal space, indicating recovery.  In contrast, there were no differences in the non-injured carotid lumens and total diameters of 8-week and 16-week CON and experiment (EXP) rats.  There were no significant differences between the blood flow velocities of the injured carotid arteries of the 8-week and 16-week cohorts over time.  However, compared to the 8-week cohort, the non-injured carotid velocity of the 16-week rats was significantly lower in both CON and EXP rats. There were no significant differences in injured carotid measurements when comparing CON to EXP rats within the same age group.