Cardioprotective Solutions Exposure For 1 Hour in Hypoxia and Low Temperatures Affects Vascular Reactivity Differently.

INTRODUCTION

Heart preservation benefits cardiac performance after operations decreasing morbidity but the contribution of the vascular reactivity has been neglected.

METHODS

We evaluated whether cardioprotective solutions, Krebs-Henseleit (KH), Bretschneider-HTK (BHTK), St. Thomas No. 1 (STH-1), and Celsior (CEL), affect vascular reactivity. Methods: Aortic rings from Wistar rats were used in two protocols. First, the rings were exposed to BHTK, STH-1 or CEL for 1 hour of hypoxia at 37 °C. Second, the rings were exposed to 10 °C or 20 °C for 1 hour under hypoxia. After treatment, the rings were immersed in KH at 37 °C, endothelial integrity was tested and concentration- response curves to phenylephrine were performed.

RESULTS

In the first protocol, the solutions did not damage the endothelium; CEL and BHTK reduced KCl-induced contractions but not STH- 1; only CEL and BHTK reduced vascular reactivity; there was a positive correlation between Rmax and KCl concentration. At 20 °C, 1 hour under hypoxia, the solutions produced similar KCl-induced contractions without endothelial damage. CEL, BHTK and STH-1 decreased vascular reactivity. At 10 °C, STH-1 increased reactivity but CEL and BHTK decreased. After 1 hour under hypoxia in CEL or BHTK solutions, reactivity was similar at different temperatures. At 20 °C, endothelial damage after exposure to STH-1 produced more vasoconstriction than CEL and BHTK. However, at 10 °C, endothelial damage after CEL and BHTK exposure elicited more vasoconstriction while STH-1 showed a small vasoconstrictor response, suggesting endothelial damage.

CONCLUSION

STH-1 decreased reactivity at 20 °C and increased at 10 °C. CEL promoted greater endothelial modulation at 10 °C than at 20 °C, while STH-1 promoted higher modulation at 20 °C than at 10 °C. Vascular tone was reduced by CEL and BHTK exposure, also depending on the KCl concentration.