Physiologic and Pathologic Influences on the Metabolism of Rat Aorta

DESPITE numerous contributions on thesubjects of atherosclerosis and arterio-sclerosis, surprisingly little is known about the metabolism of the artery and its response to different conditions. Since changes in meta-bolic pattern may affect or even precede the development of pathologic, degenerative phe-nomena of the arterial wall, an extension of investigations in this field seems necessary. Briggs et al.1 have measured the oxygen uptake of rat aorta, and Christie et al.2 have found that oxygen uptake is always higher in thoracic aorta than in abdominal aorta. The above authors state that the abdominal part is more prone to atherosclerosis. In the present communication, the metabolism of the aortic wall was investigated in rats. The effects of age, sex, special diets, and hormones on me-tabolism of aortic wall were studied. Methods The experiments were carried out on locally bred male albino rats which attain their mature weight of about 250 Gm. in 6 to 7 months. Groups of animals, 7 to 8 weeks old, weighing 100 to 120 Gm. were called "young " rats, and those not less than 1 year old, weighing about 300 Gm., were called "old " rats. Both groups were kept at the same temperature and fed the same stock diet for at least 1 month before the experiment. Food was withheld on the evening preceding the day of sacrifice. The rats were anesthetized by intraperitoneal injection of pentobarbital. The blood was collected by scission of the abdominal aorta and vein, cooled on ice, and the serum was separated promptly by eentrifugation. The aorta was removed together with the heart and dissected free from the sur-rounding connective tissue. A segment was cut from the arch to the level of the renal artery branching, opened lengthwise and rinsed in ice-cold saline, as prepared by Itzhaki and Werthei-mer.3 Krebs-Ringer phosphate medium, pH 7.4