PERICARDIAL REPAIR DEPRESSES CANINE CARDIAC CATECHOLAMINES AND MET-ENKEPHALIN

Decreased cardiac catecholamines were observed following incision and repair of the pericardium in sham-operated vs. unoperated control dogs . Animals were assigned to five groups: unoperated, sham-operated inta ct pericardia, open pericardia, sutured pericardia and complete ventri cular sympathectomy. Hearts were collected four weeks after surgery. S ympathectomy decreased catecholamine content when compared to all othe r groups. Hearts with open/sutured pericardia contained significantly less catecholamines than controls. When the pericardium was intact or left open following incision, cardiac catecholamines were unchanged co mpared to unoperated controls. Since opioid peptides are colocalized w ith catecholamines, we measured met-enkephalin and met-enkephalin-arg- phe, proenkephalin A peptide products, in parallel samples. Similar to norepinephrine, met-enkephalin was decreased following both sympathec tomy and pericardial repair. However, met-enkephalin-arg-phe, which ma y be more associated with the myocardium than its innervation, was not changed by any treatment. The sutured pericardium more than the stres s of surgery apparently alters the tissue catecholamines and enkephali n. This may have resulted from the mechanical friction at the site of repair. Epinephrine and met-enkephalin contents in sympathectomized he arts were significantly lower than unoperated controls but were not si gnificantly different from the intermediate values observed in the sut ured group. The functional consequences of these changes on neuroendoc rine status are unclear and will require further evaluation. The resul ts also emphasize the need for careful attention to proper controls fo r surgical studies.