Effect of cryopreservation on endothelin-1 productions of human mammary artery

The aim of this study was to determine the ability of human mammary artery cells to maintain a metabolic activity by measuring the artery concentration of two vasoactive substances, endothelin-l (ET-1) and cyclic guanosyl monophosphate (cGMP), and a neurohumoral substance-neuropeptide Y (NPY)-prior to and following cryostorage; Ten distal segments of internal mammary arteries were obtained at the time of surgery in patients who had undergone coronary artery bypass grafting. One ring of each vessel served as a fresh control for the other ring that was used in cryopreservation experiments. The arteries were frozen with liquid nitrogen at a controlled rate down to -130 degrees C with an automatic freezing machine and were then stored in a liquid nitrogen vapor at -150 degrees C. After mammary artery extraction, ET-1, cGMP, and NPY concentrations were studied before and after cryopreservation. Cryopreserved, compared to fresh arteries, exhibited an increase in ET-1 (11.11+/-1.61 vs. 3.09+/-0.06 pg/mg; p=0.004) and a decrease in cGMP (9.88+/-2.04 vs. 8.55+/-2.07 p moles/mg; p<0.02), whereas there was no significant NPY variation. An increase in ET-1 and decrease in cGMP was found in 10 out of 10 and 6 out of 10 of cryopreserved artery specimen, respectively. There was no significant correlation between ET-1 and cGMP production in fresh or in cryopreserved arteries. The present method of cryostorage is effective in preserving "hormonal" mammary artery activity. However, the particularly high ET-1 concentration without associated cGMP concentration may be deleterious by increasing smooth-muscle cell proliferation and vascular tone of cryopreserved arteries. (C) 2000 Elsevier Science Ltd. All rights reserved.