Abstract
Left rabbit auricles are investigated histoenzymatically to determine the metabolic profile of atrial and sino-atrial fibers, directly or after immersion in physiological solution, normally oxygenated or submitted to anoxy. Oxygenated physiologic medium does not disturb the enzymatic profiles, excepting the NADH2-TR and the glycogen in the nodal tissue. The anoxy increases strongly the glycogenolysis in the node and considerably less in the auricular muscle. In the node, the Krebs cycle and the ATPA are also increased. In auricular fibers some enzymes of Krebs cycle diminishes (MDH, ICDH), or remain indifferent (SDH, COX). The authors conclude that, despite important changes of the activities in the sino-atrial fibers, these are better protected against anoxy, because of their more rapid adaptation facilities to unfavourable situation. The mechanism involved in this adaptive possibility remains still open.
