Endothelial function and contractility of human vena saphena magna prepared for aortocoronary bypass grafting.

The aim of this study was to examine whether contractility and endothelial function of the human saphenous vein prepared for aortocoronary bypass grafting are altered by the surgical technique, e.g. cannulation and gentle distension of the vessel. Two segments (2 cm length each) of native vena saphena magna and 2 segments (2 cm length each) of the same vessel prepared for coronary bypass grafting were taken for further experimentation. After ligation of all side branches the segments were cannulated and arranged in two systems (with two segments each) in a serial manner (system I: prepared vessel followed by a native segment; system II: native vessel followed by a prepared segment) and perfused with Tyrode's solution at a constant flow rate of 20 ml/min (PO2 = 45 mmHg). Pressure gradient was measured continuously over each segment as a function of the vessel's radius according to the Hagen-Poiseuille equation. Endothelial and smooth muscle function was checked by perfusion with increasing concentrations of acetylcholine (ACH) to provoke the release of endothelium-derived relaxing factor (EDRF) (ACH; 0.3, 1, 3, 10, 30 mumol/L) after precontraction of the vessels with 1 mumol/L norepinephrine (NE). This showed normal contractility and ACH-induced relaxation in the native vessels but a reduced contractile response and a total lack of ACH-EDRF-induced relaxation in the prepared vessels. Perfusion with 5-hydroxytrytamine (5-HT) (0.25, 0.5, 1, 10 mumol/L for 10 min each concentration) resulted in marked constriction of all vessels with preserved contractility which could be completely prevented by pretreatment with the 5-HT2-receptor antagonist ketanserine (20 mumol/L).(ABSTRACT TRUNCATED AT 250 WORDS)