Format

Send to

Choose Destination
Life Sci. 1998;63(4):275-83.

Vasorelaxant effects of purified green tea epicatechin derivatives in rat mesenteric artery.

Author information

1
Department of Physiology, Chinese University of Hong Kong, Shatin, NT. yu-huang@cuhk.edu.hk

Abstract

The effects of four epicatechin derivatives, (-) epicatechin, (-) epicatechin gallate, (-) epigallocatechin and (-) epigallocatechin gallate, isolated from jasmine green tea, on the contractions were studied in mesenteric arteries isolated from male Sprague-Dawley rats. All four derivatives (30-500 microM) non-competitively reduced the contractile response to phenylephrine in a concentration-dependent manner with epigallocatechin gallate being the most potent. The relaxant effects of epicatechin derivatives were unaffected by the ATP-sensitive K+ channel blocker glibenclamide (3 microM) or the Ca2+-activated K+ channel blocker charybdotoxin (100 nM). Four epicatechin derivatives also reduced the sustained contractions induced by phenylephrine (1 microM) and endothelin I (5 nM) in normal Krebs solution, whilst they did not relax the phorbol 12-myristate 13-acetate (TPA, 2 microM)-contracted arteries in the absence of extracellular Ca2+. In arteries contracted with 60 mM K+, each of epicatechins caused a relaxation. However, epicatechin derivatives did not affect the transient contraction induced by 100 microM caffeine in Ca2+-free solution. The present results suggest that epicatechin derivatives from green tea leaves relaxed rat mesenteric arteries probably by inhibiting Ca2+ influx. The protein kinase C-dependent contractile pathway and intracellular Ca2+ release may not be involved.

PMID:
9698036
DOI:
10.1016/s0024-3205(98)00273-2
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center