Are endothelium-derived hyperpolarizing and contracting factors isoprostanes?

The endothelium releases many vasoactive substances, including prostacyclin, nitric oxide and endothelin, in addition to several other factors about which little is known. The latter are referred to as 'endothelium-derived hyperpolarizing factors' (EDHFs) and 'endothelium-derived contracting factors' (EDCFs). Although there is much debate about the identities of EDHFs and EDCFs, a prevailing hypothesis is that they are …