Endothelin-B Receptors and Left Ventricular Dysfunction after Regional versus Global Ischaemia-Reperfusion in Rat Hearts

Abstract EN

Background.

Endothelin-1 (ET-1) is implicated in left ventricular dysfunction after ischaemia-reperfusion.

ETA and ETB receptors mediate diverse actions, but it is unknown whether these actions depend on ischaemia type and duration.

We investigated the role of ETB receptors after four ischaemia-reperfusion protocols in isolated rat hearts.

Methods.

Left ventricular haemodynamic variables were measured in the Langendorff-perfused model after 40- and 20-minute regional or global ischaemia, followed by 30-minute reperfusion.

Wild-type (n=39) and ETB-deficient (n=41) rats were compared.

Infarct size was measured using fluorescent microspheres after regional ischaemia-reperfusion.

Results.

Left ventricular dysfunction was more prominent in ETB-deficient rats, particularly after regional ischaemia.

Infarct size was smaller (P=0.006) in wild-type (31.5±4.4%) than ETB-deficient (45.0±7.3%) rats after 40 minutes of regional ischaemia-reperfusion.

Although the recovery of left ventricular function was poorer after 40-minute ischaemia-reperfusion, end-diastolic pressure in ETB-deficient rats was higher after 20 than after 40 minutes of regional ischaemia-reperfusion.

Conclusion.

ETB receptors exert cytoprotective effects in the rat heart, mainly after regional ischaemia-reperfusion.

Longer periods of ischaemia suppress the recovery of left ventricular function after reperfusion, but the role of ETB receptors may be more important during the early phases.