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Aquaporin-7 expression during coronary artery bypass grafting with diazoxide
Ahmed Shalaby1, Ari Mennander, Timo Rinne
1Heart Center, Cardiac Research, Tampere University Hospital, Tampere, Finland.
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.
Insights
Diazoxide treatment during coronary artery bypass grafting (CABG) significantly reduced atrial aquaporin-7 expression, suggesting a role in managing myocardial water balance and glycerol supply.
Area of Science:
- Cardiovascular Research
- Molecular Biology
- Ischemia-Reperfusion Injury
Background:
- Aquaporin-7 (AQP7) is a glycerol channel protein crucial for tissue glycerol supply, particularly after ischemic events.
- Diazoxide, a mitochondrial K(ATP)-channel opener, is hypothesized to mitigate myocardial edema during coronary artery bypass grafting (CABG).
Purpose of the Study:
- To investigate the effect of diazoxide on atrial aquaporin-7 expression in patients undergoing CABG.
- To explore the potential of diazoxide in modulating myocardial water balance and glycerol metabolism during cardiac surgery.
Main Methods:
- A prospective study involving 16 patients with coronary artery disease undergoing CABG.
- Eight patients received diazoxide during cardiopulmonary bypass; eight served as controls.
- Atrial biopsies were collected pre- and post-operation, and aquaporin-7 expression was quantified using RT-PCR.
Main Results:
- Baseline atrial aquaporin-7 expression varied among patients, correlating with myocardial ischemia severity.
- Post-CABG, aquaporin-7 expression was elevated in most controls but significantly lower in diazoxide-treated patients.
- Relative aquaporin-7 expression was significantly reduced in the diazoxide group compared to controls (p < 0.05).
Conclusions:
- Diazoxide administration during CABG appears to decrease atrial aquaporin-7 expression.
- This reduction suggests diazoxide may influence myocardial water balance and glycerol energy supply post-surgery.
