Endothelial dysfunction after long-term cold storage in HTK organ preservation solutions: effects of iron chelators and N-alpha-acetyl-L-histidine.
BACKGROUND
To improve the rate of successful heart transplantations, organ preservation should be optimized in cardiac transplantation surgery. Iron-dependent oxidative damage and iron-independent, chloride-dependent injury of the endothelium have been described after cold ischemic storage and reperfusion, leading to an enhanced rate of complications and unfavorable outcomes. This screening study tested the effects of iron chelator supplementation in different histidine-tryptophan-ketoglutarate (HTK) organ preservation solutions on endothelial function in a long-term storage model of the isolated rat aorta.


METHODS
Isolated rat aortic rings underwent a 24-hour cold ischemic preservation in different HTK solutions supplemented with iron chelators of low (deferoxamine) and high (LK-614) membrane permeability. In vascular reactivity measurements we investigated the phenyleprine-induced contraction and both endothelium-dependent and -independent vasorelaxation by using cumulative concentrations of acetylcholine and sodium nitroprusside with and without an additional external oxidant injury during re-oxygenation.


RESULTS
Traditional HTK solution, Custodiol, failed to prevent endothelial dysfunction in our experiments. Use of chloride-poor HTK solutions containing N-alpha-acetyl-l-histidine with and without supplementation with LK-614, but not with deferoxamine, resulted in significant improvement of impaired endothelial function; moreover, complete protection of the endothelium was feasible after 24-hour cold storage. Endothelium-independent functions of vascular smooth muscle were not affected in any of the groups.


CONCLUSIONS
Our results demonstrate the important pathophysiologic role of iron-dependent oxidative injury in the development of endothelial dysfunction after cold storage, which can be prevented by cell-permeable iron chelators.
Radovits
Tamás
T
Department of Cardiac Surgery, University of Heidelberg, Heidelberg, Germany. radovitstamas@yahoo.com
Lin
Li-ni
LN
Zotkina
Julia
J
Koch
Achim
A
Rauen
Ursula
U
Köhler
Gernot
G
Karck
Matthias
M
Szabó
Gábor
G
D000818:Animals; D001011:Aorta; D015925:Cryopreservation / Q000379:methods; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000473:pathology; D005947:Glucose / Q000009:adverse effects / Q000494:pharmacology; D006639:Histidine / Q000494:pharmacology*; D007502:Iron Chelating Agents / Q000494:pharmacology*; D008297:Male; D008353:Mannitol / Q000009:adverse effects / Q000494:pharmacology; D023421:Models, Animal; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009926:Organ Preservation / Q000379:methods*; D011189:Potassium Chloride / Q000009:adverse effects / Q000494:pharmacology; D011336:Probability; D011343:Procaine / Q000009:adverse effects / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013997:Time Factors
C039984:Bretschneider cardioplegic solution; D007502:Iron Chelating Agents; D008353:Mannitol; D006639:Histidine; D011343:Procaine; D011189:Potassium Chloride; D005947:Glucose