Beneficial impact of FK 409 as donor pretreatment on warm or cold ischemically injured hearts in the rat

Cardioprotective effects of FK409, a nitric oxide donor, after isolated rat heart preservation for 16 hours

BACKGROUND

We examined the cardioprotective effects of FK409, a nitric oxide donor, after isolated rat heart preservation.

METHODS

FK409 was administered to the hearts in pretreatment (FK409-1 group), during ischemia (FK409-2), or during reperfusion (FK409-3). The combined nitrate and nitrite level, coronary flow, cardiac function, coronary vasodilatory response, creatine kinase (CK), and myocardial water content were evaluated after the hearts had been preserved in University of Wisconsin solution at 0 degrees C for 16 hours.

RESULTS

The release of nitrate and nitrite increased in reperfusion between the 20-to-40-second measurement and the measurement at 40 minutes, and the recovery of cardiac function was significantly improved in the FK409 groups. The coronary vasodilatory response to acetylcholine chloride was enhanced in the FK409-1 and FK409-2 groups. CK release decreased in FK409 groups after 15 minutes in reperfusion.

CONCLUSIONS

This study suggests that FK409 has the best protective effect on cardiac function and coronary endothelial function when it is administered in the ischemic period, a less protective effect when administered during pretreatment, and the least protective effect when FK409 is given during reperfusion after heart preservation for 16 hours.

FK409 ameliorates ischemia-reperfusion injury in heart transplantation following 12-hour cold preservation

OBJECTIVE

FK409 is the first spontaneous nitric oxide donor to increase plasma guanosine 3':5'-cyclic monophosphate. We designed this study to investigate whether the administration of FK409 during reperfusion ameliorated ischemia-reperfusion injury and enhanced post-transplant graft function in orthotopic heart transplantation following 12-hour cold preservation in a canine model.

METHODS

We used 10 pairs of adult mongrel dogs, weighing 9.5 to 13.5 kg. Following cardiac arrest using cardioplegia, we washed out the coronary vascular beds with cold University of Wisconsin solution followed by 12-hour preservation. After preservation, we performed orthotopic transplantation. The experimental animals were divided into 2 groups. In the FK group (n = 5), FK409 (5 microg/kg/min) was administered intravenously, beginning 15 minutes before the onset of reperfusion and continuing for 45 minutes after reperfusion. In the control group (n = 5), saline vehicle was administered in the same manner. Two hours after transplantation, we assessed cardiac function, including cardiac output, left ventricular systolic pressure (LVP), and the maximum rates of positive and negative increase of LVP (+/-LV dP/dt) by comparing the recovery rate (%) of the cardiac function of the donor animal. We measured endothelin-1 levels in blood obtained from a catheter inserted into the coronary sinus 30, 60, and 120 minutes after reperfusion.

RESULTS

Cardiac output was higher in the FK group than in the control group, but the difference was not significant (p = 0.08). Left ventricular systolic pressure and +/-LV dP/dt were significantly (p < 0.05) higher in the FK group than in the control group. Endothelin-1 levels were significantly (p < 0.05) lower in the FK group than in the control group 30 minutes after reperfusion. Transmission electron microscopy showed that the basal lamina of capillary vessels, glycogen granules, and mitochondrial structure were well-preserved in the FK group.

CONCLUSIONS

In orthotopic transplantation models, FK409 is effective in ameliorating ischemia-reperfusion injury following preservation and in enhancing post-transplant cardiac function.

Prior induction of heat shock proteins by a nitric oxide donor attenuates cardiac ischemia/reperfusion injury in the rat

BACKGROUND

Recent studies have demonstrated that nitric oxide (NO) releasers considerably increase heat shock proteins (HSPs) in the in vitro cell system, providing resistance to oxidant damage. This study was designed to examine the cellular responses of HSPs induced by prior administration of an NO releaser, FK409 (FK), in an in vivo transplantation model.

METHODS

Lewis rats received either saline or FK solution intravenously administered at different time points before graft harvesting (10 micromol/kg) or for 15 min during reperfusion (0.66 micromol/kg/min). Tissue specimens were taken to determine HSP70 and heme oxygenase-1/HSP32 (HO-1) expression, and glutathione content. After 24-hr preservation with University of Wisconsin solution, heterotopic cardiac transplantations were performed, and graft survival was determined at 14 days. Tissue samples for end labeling of nuclear DNA fragments (TdT-mediated d-uridine triphosphate biotin nick end labeling; TUNEL) and propidium iodide staining were taken 15 min after reperfusion.

RESULTS

The gene and protein expression of HSP70 after FK administration peaked at 12 min and 60-90 min, whereas those of HO-1 peaked at 6 min and 90 min, respectively. Then, representative cardiac grafts taken 60 min after FK treatment were examined for further assay. Localization of induced HSP70 and HO-1 molecules were observed in the myocardium and vascular endothelium, respectively. Prior treatment of FK was effective in preventing the reduction of tissue glutathione contents compared with control (P<0.05). Fewer TUNEL and propidium iodide-positive cells were also observed in the FK group (P<0.0005, vs. control). The graft survival rate was higher in the FK group (9/10 vs. 1/10 of control; P<0.001), whereas the groups either harvested 10 min after FK pretreatment or continuously infused for 15 min during reperfusion were inferior, similar to that of control.

CONCLUSION

Prior induction of HSP70 and HO-1 with a relatively low dose of FK administration attenuates ischemia and reperfusion injury, which was due to antioxidant and antiapoptotic activities augmented by such stress proteins. Thus, NO releasers as a pharmacological maneuver may provide an innovative approach for the prevention of ischemia and reperfusion injury.