Species-dependent differences in the nature of endothelium-derived vascular relaxing factor

Effluents from perfused acetylcholine-relaxed endothelium segments of rabbit aorta (or canin femoral artery) contained endothelium-derived relaxing factors (EDRF) which dilated the endothelium-free segments of rabbit femoral artery (or side branches of canine femoral artery). The half-life of EDRF was 24 +/- 3 s for the rabbit and 49 +/- 5 s for the canine system. Nordihydroguaiaretic acid was less effective against the formation of canine EDRF than of rabbit EDRF. These findings suggest species differences in the nature of EDRF.