Key result
Endothelium-dependent relaxation responses to acetylcholine in the canine venous system are regionally different, with marked relaxations in some veins and only contractile responses in others.
This preclinical study demonstrates significant regional heterogeneity in endothelium-dependent relaxation responses to acetylcholine across the canine venous system.
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No immediate clinical implications; leaves open whether regional endothelial heterogeneity translates to human veins.
Endothelium-dependent relaxations of canine veins isolated from 15 different sites were examined. Acetylcholine (ACh, 10(-10)-10(-6) M) caused marked endothelium-dependent relaxations in the external jugular vein, superior vena cava, brachiocephalic vein, segment A (supradiaphragmatic portion) and D (infrarenal portion) of the inferior vena cava. However, only contractile responses were induced by ACh in the portal, mesenteric veins and the segment C of the inferior vena cava (between liver and renal veins) with or without endothelium. The other 7 veins showed only small endothelium-dependent relaxations (10-20%). These results indicated that the endothelium-dependent responses of canine veins to ACh are regionally different.
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Furuta et al. (1987) studied Healthy (animal model). Acetylcholine vs. Endothelium-denuded veins and different regional veins was evaluated on Maximal relaxation expressed as percent of induced active tone. Endothelium-dependent relaxation responses to acetylcholine in the canine venous system are regionally different, with marked relaxations in some veins and only contractile responses in others.
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