EFFECTS OF BQ-123, AN ET(A) RECEPTOR ANTAGONIST, ON MYOCARDIAL STUNNING IN ISOLATED RAT HEARTS

This study was performed to evaluate the effects on mechanical and met abolic function of endogenous endothelin-l on post-ischaemic myocardia l stunning. Isolated rat hearts were given BQ-123 (710 nM) or vehicle alone before being subjected to 20 min of global low flow ischaemia an d 60 min reperfusion. Left ventricular mechanical function was assesse d as developed and end-diastolic pressure, maximum positive and negati ve derivatives of pressure and time constant of relaxation. Compared t o controls, administration of BQ-123 was associated with a tendency to lower diastolic pressures during ischaemia (23.0 +/- 7.0 vs 34.2 +/- 7.4mmHg) and early reperfusion (15.5 +/- 3.3 vs 19.8 +/- 4.4mmHg at 15 min, n = 7/8). However, none of the analysed variables were statistic ally different between the two groups. BQ-123 does not offer protectio n against myocardial stunning in isolated rat hearts. However, a tende ncy to higher ventricular compliance as compared to controls, if confi rmed, might be clinically important.