Effect of Low Iron Intake on Hepatic Vasodepressor Material, Plasma Iron and Adrenaline Thresholds of Mesocecal Vessels in Rats

¹ From the Department of Physiology, Stanford University, Stanford, California

Dietary manipulation of iron in rats was accomplished by means of iron-deficient and iron-rich diets. Rats fed the low iron diet developed moderate anemia and had low plasma iron concentrations. Livers from animals kept on low Fe 28–60 days were low in iron content and yielded, under anaerobic incubation, extracts that had none of the vasodepressor effect found in similar extracts from livers of normally fed rats. Rats subsisting on diets containing 2.0 mg of Fe/gm of diet (10 times the Fe of stock ration) had high plasma iron concentrations, high hemoglobin levels and yielded liver extracts with potent vasodepressor action. The iron contents of crude, anaerobic extracts of livers from iron-supplemented rats were higher than those from livers of animals on stock or low iron diets. Vascular beds, in rats kept on low iron diets, had fewer open blood vessels and showed spontaneous vasomotion. Adrenaline thresholds were from 0.12 to 0.20 µg adrenaline/ml while those of the animals on stock diet or iron-supplemented diet were in the normal range, between 0.30 and 0.50 µg/ml. Chronic depletion of iron apparently interfered with the ability of the liver to elaborate or release vasodepressor material under anaerobic conditions; blood vessels of these iron-depleted animals have increased responsiveness to adrenaline as judged from lowered adrenaline thresholds.