C.: Adrenal medullary secretion during hypoxia, bleeding and rapid intravenous infusion. Circulation Research 9: 427

PREVIOUS studies have indicated thatreduced tissue oxygen supply due to hy-poxia or to hemorrhagic hypotension may increase adrenal medullary secretion. Cannon and Hoskins1 studied asphyxiated cats by sampling inferior vena caval blood from an area just above the adrenal veins. These work-ers demonstrated inhibition of rabbit intestine contraction by vena caval blood during as-phyxia, suggesting epinephrine release. Hous-say and Molinelli2 anastomosed the left lumbo-adrenal vein of the dog to the jugular vein of another dog. Hypoxia in the donor animal produced tachycardia and increased systemic blood pressure in the recipient, suggesting in-creased adrenal medullary secretion. Baugh, Cornett, and Hatcher3 produced hypoxia in dogs by 6 per cent 02 in N2 breathing and observed an increase of cardiac output, stroke volume, heart rate, respiratory rate, and hem-atocrit. These changes were prevented or moderated by adrenalectomy. Blood removed from intact anoxic dogs increased cardiac out-put significantly in assay dogs. Watts4 and Watts and Bragg,5 employing a bio-assay method, found an increase of arte-rial blood epinephrine in bled dogs; epineph-rine levels increased after bleeding 15 ml./Kg. and reached a maximum after bleeding 40 ml./ Kg. Walker and associates,6 using a chemical method, observed augmentation ratios of 1.8 to 59.1 of adrenal vein catecholamines in dog