Green tea modulates alpha(1)-adrenergic stimulated glucose transport in cultured rat cardiomyocytes.
alpha1-Adrenergic stimulation triggers glucose transport in the heart through the translocation of glucose transporter (GLUT) 1 and GLUT4 to plasma membranes, mediated by protein kinase C (PKC) isoforms. Evidence is emerging that dietary polyphenolic compounds may act not only as antioxidants but also by modulating PKC-mediated signaling. This study evaluated the ability of a green tea extract (GTE) to modulate alpha1-adrenoceptor-mediated glucose transport in rat cardiomyocytes. GTE supplementation decreased phenylephrine (PhE)-stimulated glucose uptake and GLUT4 recruitment. PhE stimulation activated PKC alpha, beta, delta, and epsilon, while GTE supplementation decreased the translocation of beta and delta isoforms, but not alpha and epsilon, supporting the notion that GTE directly affects PKC activation and is a beta and delta isoform-selective PKC inhibitor. Due to reactive oxygen species (ROS) involvement in pathological heart alterations, the observation that GTE is able to both inhibit effects originated by some PKC isoforms and counteract ROS deleterious effects could be important in the prevention/counteraction of these diseases.
Department of Biochemistry G.Moruzzi, Via Irnerio 48, University of Bologna, 40126 Bologna, Italy.
Cristina
C
Angeloni
Tullia
T
Maraldi
Anna
A
Ghelli
Michela
M
Rugolo
Emanuela
E
Leoncini
Gabriele
G
Hakim
Silvana
S
Hrelia
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D028241:Camellia sinensis / Q000737:chemistry*; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000032:analysis / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000737:chemistry / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects* / Q000502:physiology
D051275:Glucose Transporter Type 4; D010936:Plant Extracts; D018340:Receptors, Adrenergic, alpha-1; C495694:Slc2a4 protein, rat; D011493:Protein Kinase C; D005947:Glucose