Effect of signaled versus unsignaled stress of rat myocardium

Foot-shock stress resulted in a threefold increase in myocardial uptake of technetium-99m-methylene diphosphonate (Tc-99m-MDP) in rats compared to unstressed controls. The introduction of a 4-sec signal prior to each shock resulted in a two-thirds reduction in this stress-induced Tc-99m-MDP myocardial uptake, suggesting that most of the stress-induced myocardial damage was psychologically mediated.