Differentiation of in vitro and in vivo effects of a flavonoid on endothelial cell counts.

Parenterally administered flavonoids decrease endothelaemia in rats as determined by a new method in two ways: in vivo and in vitro. The in vitro effect caused by flavonoids present in blood might interfere with the cell counting and can be eliminated by neutralization of flavonoids with cobaltous ions. The resulting endothelial counts represent the "true" in vivo effect. Using this method it has been shown that the in vitro interference did not modify significantly the previously demonstrated marked effect of a flavonoid (mono-7-hydroxyethylrutoside) on increased endothelial counts after provocation with citrate.