ENDOTHELIUM-DEPENDENT CONTRACTION OF CANINE CORONARY-ARTERY IS ENHANCED BY CRYSTALLOID CARDIOPLEGIC SOLUTION

Experiments were designed to determine whether hyperkalemic crystalloi d cardioplegic solution enhances endothelium-dependent contraction of coronary arteries, Segments of canine coronary arteries (n = 8 in each group) were preserved in cold (4 degrees C) crystalloid cardioplegic solution (group 1) and physiologic solution (group 2) for 60 minutes. Segments of preserved and control (group 3) coronary arteries with or without endothelium were suspended in organ chambers to measure isomet ric force. Perfusate hypoxia (oxygen tension 35 +/- 5 mm Hg) caused en dothelium-dependent contraction in the arteries of all three groups. H owever, vascular segments with endothelium of group 1 exhibited hypoxi c contraction (68.5% +/- 15.3% of the initial tension contracted by pr ostaglandin F-2 alpha 2 x 10(-6) mol/L, p < 0.05) that was significant ly greater than contraction of the group 2 and group 3 segments with e ndothelium (26.6% +/- 5.6% and 20.6 +/- 4.4%). The hypoxic contraction in arteries of group 1 could be attenuated by N-G-monomethyl-L-argini ne, the blocker of endothelial cell synthesis of the nitric oxide from L-arginine. The action of N-G-monomethyl-L-arginine could be reversed by L-arginine but not D-arginine. Thus after preservation with cardio plegic solution, augmented endothelium-dependent contraction.