Mg. Davies et al., FUNCTIONAL AND HISTOLOGICAL DIFFERENCES IN AUTOGENOUS AND ALLOGENIC VEIN GRAFTS - 2 DIFFERENT VASCULOPATHIES, The Journal of surgical research, 69(1), 1997, pp. 14-22
The long-term biological characteristics and the functional and morpho
logical changes that occur in fresh allografts are poorly understood.
This study tests the hypothesis that the development of intimal hyperp
lasia and its associated functional changes are accelerated in an allo
graft compared to an autograft due to the additional immunological sti
muli. Common carotid vein bypass grafts were performed in 40 New Zeala
nd White rabbits: 20 received their ipsilateral jugular veins (autolog
ous) and 20 received the fresh contralateral jugular veins from the co
ntrol. rabbit (allogenic), Electron microscopy was performed and intim
al and medial dimensions were determined by videoplanimetry at 7, 14,
and 28 days. Contraction and relaxation studies to a panel of agonists
were also performed. The EC50's (agonist concentration which produces
50% of the maximal response) were calculated. Ail grafts remained pat
ent. Allografts showed a 51% decrease in overall mean intimal thicknes
s (41 +/- 3 mu m vs. 83 +/- 12 mu m; P < 0.01) and a 97% increase in o
verall mean medial thickness (140 +/- 15 mu m vs. 71 +/- 3 mu m; P < 0
.01) compared to the autografts. The lumen of the allogenic vein graft
s was equivalent to the autologous vein grafts. Overall mean total wal
l thickness only increased by 17%, 181 mu m vs. 154 pm for allo- and a
utografts, respectively, The EC50 for norepinephrine, histamine, and b
radykinin were similar in the auto- and allografts, while the EC50 to
serotonin was significantly less in the allografts than in the autogra
fts. Neither the precontracted auto- or allografts relaxed to acetylch
oline or serotonin (receptor mediated, endothelium dependent). The EC5
0 for calcium ionophore (nonreceptor mediated, endothelium dependent)
was equivalent in the auto- and allografts. The EC50 for the sodium ni
troprusside-induccd relaxation (endothelium independent) was significa
ntly higher in the allograft than ill the autograft. This study demons
trates that there are two different vasculopathies occurring in autogr
afts and allografts: intimal hyperplasia is predominant in the autogra
ft while an exaggerated medial response is predominant in the allograf
t. Serotonin contractility and endothelial-independent relaxation are
enhanced in the allograft compared to the autograft, (C) 1997 Academic
Press.