Effects of hypothermosol, an experimental acellular solution for tissue preservation and cardiopulmonary bypass, on isolated newborn lamb coronary vessels subjected to ultra profound hypothermia and anoxia

Ultra profound hypothermia (4 to 10 degrees C) is an experimental method ai ming at safely prolonging organ and total body preservation. For this purpo se, Hypothermosol (HTS), an investigational acellular solution for blood su bstitution, was demonstrated to be beneficial in animal models undergoing c ardiopulmonary bypass. We investigated the beneficial versus deleterious ef fects of cold preservation and the role of HTS on isolated coronary arterie s (CA) during cold exposure, rewarming, and post-rewarming exposure to anox ia. Newborn lamb CA rings were studied using a tissue bath technique. CA we re subjected to cold (7 degrees C for 3 h) and treated with either Krebs' b uffer (Krebs/ hypothermia) or HTS (HTS/hypothermia) (n = 15 each). A third group maintained at 37 degrees C (Krebs/normothermia) (n = 18) served as a time control. After rewarming (37 degrees C), precontracted CA were exposed to anoxia. In Krebs/hypothermia a substantial hypercontraction (g) occurre d during rewarming (1.21 +/- 0.07) (mean +/- SEM) but not in HTS/hypothermi a (0.79 +/- 0.03); P < 0.05. Precontraction force generated by indomethacin /U46619 was identical in all three groups. However, Krebs/hypothermia vesse ls demonstrated a significantly higher relative vasoconstriction percentage in the early (similar to 10 min) and late (30 min) anoxia exposure than th e HTS/hypothermia and time control (119.5% +/- 3.7 vs 109.5% +/- 4.4 and 10 1.5% +/- 3, and 71% +/- 7.6 vs 38.9% +/- 7 and 51.5% +/- 5.9, respectively; P < 0.05). In conclusion, Ultra profound hypothermia promotes coronary vas oconstriction upon rewarming which is detrimental to relaxant response to h ypoxia Both phenomena are alleviated by performing ultra profound hypotherm ia under HTS protection. (C) 1999 Academic Press.