Do Mistletoe (Viscum album L.) Lectins Influence Isometric Contraction of Non-diseased Human Mesenteric Arteries ex vivo?

Mistletoe (Viscum album L., VA) lectins (MLs) are plant lectins with potent anticancer activity. Although wide use of VA extracts in curing cancer, the effects of purified MLs on human vasculature in term of possible side effect of the lectin has not yet been reported. The present study was aimed to investigate isometric contractions of isolated human mesenteric arteries during MLs application. The contractile response of arteries was studied using Mulvany-Halpern myograph and the isometric contractions under MLs’ treatment were examined in artery segments with either intact endothelium or after endothelium removal. Furthermore, the effect of the lectin was assessed in arterial preparations in basal tension, in arteries precontracted with 42 mM KCl as a depolarizing stimulus or endothelin-1 (ET-1) as a potent receptor-operated agonist of vascular smooth muscle contraction. The results showed that MLs (1 to 100 nM) failed to affect the high K+-induced contractions of both endothelium-intact and endothelium-denuded arteries. The contractions of tissue preparations without endothelium in basal tone or after ET-1 (1 nM) treatment were also not affected by the application of MLs. The observed mild effect of MLs on the contractility of human vasculature may potentially be beneficial with MLs-based anticancer therapy without vascular side effects.