These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Vitamin K antagonism of coumarin intoxication in the rat.
    Author: Wallin R, Patrick SD, Ballard JO.
    Journal: Thromb Haemost; 1986 Apr 30; 55(2):235-9. PubMed ID: 2424118.
    Abstract:
    An in vitro system which expresses all enzyme activities related to vitamin K-dependent carboxylation of blood clotting factors was prepared from livers of rats overdosed with warfarin, difenacoum and dicumarol respectively. In this system, the activities of the two pathways that are known to produce active reduced vitamin K1 cofactor for the carboxylation reaction were measured. Also the ability of high concentrations of vitamin K1 to overcome inhibition of clotting factor synthesis was studied. In the systems prepared from livers of warfarin and difenacoum intoxicated rats, pathway I was inactive. Vitamin K epoxide reductase was also inactive which strongly suggests that this enzyme catalyzes the activity of pathway I in vivo. Reduction of vitamin K1 by pathway II bypassed the inactive pathway I and resulted in carboxylation activity. This pathway therefore mediates the antidotic effect of vitamin K1 in the coumarin intoxicated liver. In the in vitro system prepared from dicumarol intoxicated livers the activity of pathway I was not significantly affected. Dicumarol however was a strong inhibitor when added to liver microsomes in vitro.
    [Abstract] [Full Text] [Related] [New Search]