RETENTION OF ENDOTHELIUM-DEPENDENT PROPERTIES IN HUMAN MAMMARY ARTERIES AFTER CRYOPRESERVATION

Background. We investigated the effects of cryopreservation and antibi otic treatment on endothelium-dependent vasomotor properties of human internal mammary arteries (IMAs). Methods. Sixty IMA specimens from ro utine coronary artery bypass grafting procedures were randomly assigne d to six groups. Group I(controls) were immediately tested after harve st. Remaining groups were prepared according to a stepwise design: gro up II, 6 hours of warm ischemia; group Ill, 6 hours of warm ischemia 24 hours at 4 degrees C (without antibiotics); group IV, 6 hours of w arm ischemia + 24 hours of 4 degrees C antibiotic disinfection; group V, 6 hours of warm ischemia + 24 hours at 4 degrees C (without antibio tics) + cryopreservation; and group VI, 6 hours of warm ischemia + 24 hours of 4 degrees C disinfection + cryopreservation. The IMA specimen s were cut into rings and the tension of vascular smooth muscle was re corded. The IMA rings were contracted with norepinephrine (3 x 10(-6) mol/L) and tested with cumulative concentrations of acetylcholine (fro m 1 x 10(-9) to 1 x 10(-5) mol/L), contracted with endothelin-1 (from 1 x 10(-11) to 1 x 10(-6) mol/L), and contracted with the nitric oxide -synthase inhibitor N-G-monomethyl-L-arginine (1 x 10(-4) mol/L). Ring s were also tested for their capacity to generate 6-keto-prostaglandin F-1 (the stable metabolite of prostacyclin), and endothelial cell via bility rate was finally evaluated with the trypan blue dye exclusion m ethod. Results. Our results show that a complete cryopreservation prot ocol does not significantly modify (p > 0.05) the relaxant activity to acetylcholine in norepinephrine-precontracted IMA rings (controls; 90 .2% +/- 4.2% vs group VI, 77.1% +/- 6.2%) or the vasoconstrictor respo nse induced by endothelin-1 (controls, 62.6% +/- 2.8% versus group VI, 73.7% +/- 4.8%) and N-G-monomethyl-L-arginine (controls, 22.4% +/- 1. 5% versus group VI, 18.9% +/- 1.9%). Furthermore, IMA cryopreservation does not significantly modify (p > 0.05) the endothelial release of p rostacyclin either in basal conditions (-20% versus controls) or durin g pharmacologic intervention with acetylcholine (-18% versus controls) , endothelin-1 (-17% versus controls), and N-G-monomethyl-L-arginine ( -18% versus controls). Conclusions. We conclude that the IMA endotheli al function does not seem significantly injured by any of the current steps of disinfection and cryopreservation.