Aquaporin-7 expression during coronary artery bypass grafting with diazoxide.

Abstract

Objectives: Aquaporin-7 is a water-channel protein that controls tissue glycerol supply after ischemia. A burden of experimental studies suggests that diazoxide, a mitochondrial K(ATP)-channel opener, may decrease myocardial edema during coronary artery bypass grafting (CABG). We evaluated whether diazoxide has an impact on atrial aquaporin-7 expression during CABG.

Design: Sixteen patients with a history of stable coronary artery disease were enrolled in the study. Eight patients were treated during cardiopulmonary bypass with diazoxide, while the rest eight patients remained as controls. Histopathology was evaluated from biopsies procured before and during CABG from the right atrium. From fresh atrial tissue biopsies, Aquaporin-7 was quantified by RT-PCR.

Results: Histological differences were apparent between individual patients already before operation at base line reflecting differences in severity of myocardial ischemia. As compared with fold change values before operation, Aquaporin-7 expression after operation was positive in all but one control, whereas aquaporin-7 expression was positive in only two patients receiving diazoxide. The relative aquaporin-7 expression was significantly lower in patients treated with diazoxide as compared with controls (p < 0.05).

Conclusions: Diazoxide may have an impact on myocardial water balance and glycerol energy supply by decreasing relative aquaporin-7 expression during CABG.