No change in alpha 1 adrenoceptors in canine femoral arteries after lumbar sympathectomy.

In the dog, alpha 1 adrenoceptors have been identified in the aorta, femoral mesenteric, and renal arteries. The concentration of alpha receptors may be regulated by hormones such as estrogen and progesterone and by drugs such as epinephrine. To assess whether sympathetic denervation, which is known to decrease norepinephrine output, might change the population of alpha 1 receptors in vascular smooth muscle, the femoral artery alpha 1 receptor population was examined 2 weeks after unilateral lumbar sympathectomy. [3H]Prazosin radioligand receptor assay analysis was used to measure the alpha 1 receptor populations. No statistical difference for dissociation constant and receptor density values between sympathectomy and nonsympathectomy femoral artery samples could be detected.

The etiology of symptoms in patients with recurrent carotid stenosis.

We performed 33 carotid endarterectomies in 29 patients for recurrent carotid stenosis. The interval between the initial and second operations ranged from six weeks to 11 years with a mean of 56 months. Three types of pathologic lesions were identified: (1) recurrent atherosclerosis (RA), (2) neointimal fibromuscular hyperplasia (NFH), and (3) lesions with elements of both RA and NFH (complex lesions). Histologic examination of early-recurring lesions (less than three years) revealed NFH in 17 patients and one complex lesion. Late-recurring lesions (three years or later) were due to atherosclerosis in eight vessels, NFH in four, and both RA and NFH in three. Focal neurologic symptoms occurred in 25 (76%) of 33 vessels, and an embolic source could be identified in 16 (64%) of 25 patients. Embolic events rather than reduced blood flow due to progressive stenosis are more frequent causes of symptoms in patients with recurrent carotid stenosis than was formerly believed.