Abstract
Background: Activation of polymorphonuclear neutrophils (PMN) and subsequent release of free
oxygen radicals, including the superoxide anion (O2
-) has been shown to result in postischaemic myocardial dysfunction during coronary
artery bypass grafting (CABG). Several neutrophiloriented stimuli are known to be
released from myocardium during ischaemia and reperfusion. Release of endothelin-1
has been documented during CABG. The aim of the current study was to evaluate plasma-mediated
neutrophil stimulation and to verify whether endothelin-1, known to be a stimulus
for PMN, is involved in plasma-mediated stimulation of PMN during coronary artery
bypass grafting. Methods: Plasma samples from peripheral artery, peripheral vein, and coronary sinus were obtained
from 21 patients undergoing CABG before aortic clamping (global ischaemia), immediately
after beginning reperfusion, and 30 min after reperfusion as well as from healthy
controls. Plasma was incubated with PMN isolated from healthy donors preincubated
in the presence of saline or specific endothelin-1 receptor antagonist (ET-A). PMN
O2
- production was measured spectrophotometrically. Results: Plasma samples taken from the coronary sinus at the beginning of reperfusion were
capable of higher stimulation of neutrophil superoxide anion production (24.2±2.0
nmol/5×106PMN/30 min) than plasma obtained before reperfusion (15.6± 1.5; p <0.05) or plasma
taken from peripheral artery (17.1 ±1.7; p <0.05). Preincubation of PMN with endothelin-1
receptor antagonist decreased superoxide anion production by cells exposed to plasma
taken from coronary sinus at the beginning of reperfusion (17.6 ± 2.0, p<0.05). Conclusions: Transcardiac release of soluble stimuli for PMN occurs as a result of myocardial
ischaemia during CABG. Endothelin-1 may be involved in the plasma-mediated stimulation
of neutrophil superoxide anion production.
Key words
Coronary artery bypass grafting - Polymorphonuclear neutrophils - Superoxide anions
- Endothelin-1
