Son las sustancias que produce el propio organismo y tienen la capacidad de provocar vasodilatación, entre ellas el [[óxido nítrico]], la [[histamina]], la [[bradicinina]], la [[sustancia P]] y el [[péptido intestinal vasoactivo]].<ref name="pmid6129023">{{cite journal | autor = Fahrenkrug J, Emson PC | title = Vasoactive intestinal polypeptide: functional aspects | journal = British Medical Bulletin | volume = 38 | issue = 3 | pages = 265–70 | date = Sep 1982 | pmid = 6129023 | url = http://bmb.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=6129023 }}</ref> <ref name="pmid9576114">{{cite journal|last=Costa|first=F|author2=Biaggioni, I |title=Role of nitric oxide in adenosine-induced vasodilation in humans.|journal=Hypertension|date=May 1998|volume=31|issue=5|pages=1061–4|pmid=9576114|doi=10.1161/01.HYP.31.5.1061}}</ref>
