Ouabain-Like Compound Changes Rapidly on Physical Exercise in Humans and Dogs: Effects of β-Blockade and Angiotensin-Converting Enzyme Inhibition

Ouabain, an inhibitor of the sodium pump, has been identified as a constituent of bovine adrenal glands. We were interested whether the release of this cardiotonic steroid is stimulated by physical exercise. Hence, athletes and healthy dogs were subjected to ergometry. Ouabain-like compound (OLC) was measured in venous blood by enzyme-linked immunosorbent assay as well as by Rb uptake inhibition (as ouabain equivalents). OLC increased in venous blood of athletes after 15 minutes of ergometry from 2.5±0.5 to 86.0±27.2 nmol/L (n=51; P