1: Eur J Pharmacol.  2004 May 25;492(2-3):269-72.  

Marrubenol interacts with the phenylalkylamine binding site of the L-type
calcium channel.

El Bardai S, Hamaide MC, Lyoussi B, Quetin-Leclercq J, Morel N, Wibo M.

Laboratoire de Pharmacologie, Universite Catholique de Louvain, UCL 5410, Avenue
Hippocrate, 54, B-1200 Brussels, Belgium.

Marrubenol inhibits contraction of rat arteries by blocking L-type calcium
(Ca(2+)) channels in smooth muscle cells, but its interaction with binding sites
for calcium antagonists had never been investigated. Competition binding studies
indicated that marrubenol was a weak inhibitor of 1,4-dihydropyridine binding in
membranes isolated from rat intestinal smooth muscle but completely displaced
specifically bound (-)-[(3)H]desmethoxyverapamil ([(3)H]D888) with an apparent
K(i) value of 16 microM (95% confidence interval: 6.5-39.5 microM). As
marrubenol inhibited the contraction evoked by KCl depolarization of intestinal
smooth muscle half-maximally at a concentration of approximately 12 microM,
interaction with the phenylalkylamine binding site seems to account for the
inhibition of L-type Ca(2+) channels by marrubenol.

PMID: 15178374 [PubMed - in process]