CONTRACTILITY OF THE RABBIT ABDOMINAL-AORTA 4 DAYS AFTER ENDOTHELIUM DENUDATION

The purpose of this study was to evaluate contractility of the rabbit abdominal aorta 4 days after de-endothelialization by balloon catheter . The isometric tension of ring-segments in response to vasoactive age nts was monitored. A significant enhancement of contraction to noradre naline and serotonin was found in aortas 4 days after endothelium denu dation as compared with controls with endothelium. The enhancement, ho wever, did not differ from that found already in acutely denuded vesse ls (immediate denudation). No significant difference in contractility to potassium chloride was found in either group of denuded preparation s as compared with controls. The sensitivity to all three vasoactive a gents (EC50) was not influenced by denudation. These results indicate that changes in the contractility of denuded vessels are predominantly a consequence of lacking the endothelium as a producer of endothelium -derived relaxing factor. The access of mitogens to the media does not seem to interfere with the magnitude of contraction 4 days after denu dation.