Purpose and aim: the mechanisms of cardioplegia on the endothelial and smooth muscle cells membrane are controversial, in this in vitro study we evaluated the effect of cardioplegia on structure and function of the saphenous vein.
Materials and Methods: In this in vitro study, ten segments were gently harvested and were placed in 10ml organ bath chamber containing Krebs solution. After careful washout, the venous segments were first contracted with 〖10〗^(-6) mM phenylephrine to reach %75 of maximal contraction. Then the endothelial-dependent and endothelial-independent relaxations were assessed in the presence of acetylcholine (〖10〗^(-6)mM) and sodium nitroprusside (SNP) 〖10〗^(-5)mM) respectively. The vein strips were mounted again in the organ bath chamber contained cardioplegia solution with different KCl concentrations (5, 20 and 40meq) at 25°c for 30 minutes to assess contraction and relaxation response just right the procedure that previously mentioned.
Results: Endothelium-dependent relaxation to acetylcholine showed the significant difference after incubation in 40meq of KCL cardioplegic solution (p value<0.05), but there was no difference in segments incubated in 5meq and 20meq KCL cardioplegic solution. There was no significant difference in relaxation to sodium nitroprusside between segments. Dilated group: no difference was seen after incubation in the groups. (P value>0.05).Constriction with phenylephrine also showed no significant difference in all the groups. (P value>0.05). Vasorelaxation with acetylcholine and SNP showed no significant changes in the groups. Conclusion: high concentration cardioplegic solutions can depolarize endothelium and decrease endothelial-dependent vasodilation, moreover, concentrations less than 20mMol of normothermic storage solution should be used to maintain normal endothelial function.