Effects of gamma radiation on isolated surviving arteries and their vasa vasorum

¹ Department of Pharmacology, College of Medicine, The University of Vermont, Burlington, Vermont

The effects of irradiation with Co⁶⁰ on 136 swine and dog carotid arteries have been studied in vitro, utilizing an angioplethysmokymographic technique. In 20–40% of the specimens a slight vasoconstriction of the arterial wall was observed. This began and was completed within the first 60 sec of irradiation. Mounting the tissue in mineral oil did not prevent this reaction. Marked reductions in vasa vasorum flow were observed in swine carotids (70% decrease) and dog carotids (50% decrease) exposed to 9390 r of gamma radiation during 15 min. Less marked, although significant, decreases in vasa vasorum flow were seen in swine arteries exposed to 3000 r, 2085 r, and 1500 r. No significant decreases were observed in 24 arteries exposed to 843 r. Swine arteries exposed to 9390 r, while mounted in mineral oil, did not show a significant decrease in vasa vasorum flow. It is concluded that the contraction of the arterial wall was a direct effect of radiation upon the vascular smooth muscle and that the observed decrease in vasa flow was probably secondary to ionization of the Tyrode's solution surrounding the artery.