[Effects of opioid peptides on rats with a second heart transplanted into the abdominal cavity].

To determine whether opioid peptides have direct effects on myocardium we compared the effects of enkephalin analogs DAGO and DADL on both an innervated heart and a denervated heterotopically transplanted heart in the same animal. DAGO and DADL injected intravenously into anesthetized rats with two hearts produced hypotension, fall in end-systolic left ventricular pressure of both recipient's and donor's heart, bradycardia and decreasing of contractility in recipient's heart. Opioid peptides exerted no chronotropic effect and a slight positive inotropic effect on denervated transplanted heart. Both bradycardia and decreasing of contractility in recipient's heart have the neurogenic origin.