Retention of endothelium-dependent vasodilatory responses in canine coronary arteries following cryopreservation

In the present study, the cryoprotective effect of dimethyl sulfoxide (Me 2SO) and fetal calf serum (FCS) on coronary endothelium and endothelium-dependent relaxation (EDR) responses was studied in isolated canine coronary arteries following cryostorage at −75 °C. Compared to the freshly isolated coronary arteries, the EDR responses to acetylcholine, thrombin, and calcium ionophore were not significantly altered following 1 day storage at −75 °C in the presence of 1.8 M Me 2SO and 20% FCS. Prolonged cold storage to 7 days, however, resulted in a slight, but significant, rightward shift of the concentration-response curves of acetylcholine and thrombin, but not calcium ionophore. The maximum relaxant response after 7-day cryostorage was 80 to 85% of fresh controls. Omission of FCS from the cryostorage incubation medium further accentuated the loss of EDR responses to all three endothelium-dependent vasodilators tested. Scanning electron microscopic examinations of the intimal surface of the Me 2SO and FCS cryostored canine coronary arteries confirmed the preservation of intimal endothelial cells following 1 or 7 days of storage at −75 °C, while significant patches of loss of endothelial cells were observed in the arteries cryostored only in the presence of Me 2SO. No significant inhibitory effect of cryostorage was observed for the direct, endothelium-independent relaxation induced by isoproterenol, regardless of the presence or absence of FCS. These results demonstrate that slow freezing of canine coronary arteries to −75 °C in Krebs-Henseleit solution containing Me 2SO and FCS provides good preservation of the vascular smooth muscle function and endothelium-dependent vasodilatory responses.