P839Lectin-like oxidized low density lipoprotein receptor-1 exhibits increased expression in the epicardial coronary arteries in patients with coronary artery disease. The intramyocardial paradox

Background: Intramyocardial paradox is defined as the difference in atherosclerosis between the intramyocardial and epicardial parts of the coronary arteries in patients with coronary artery disease. The lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) expression has been implicated in the early steps of atherogenesis and may interfere with many factors to induce atherosclerosis. Purpose: These evidences prompted us to investigate the role of LOX-1 as a part of an atherogenetic mechanism by measuring and comparing LOX-1 expression in human epicardial and intramyocardial coronary arteries. Methods: An epicardial and an intramyocardial total artery wall specimen was obtained from 13 male patients, aged 61.9±10.3 years, that underwent coronary artery bypass graft surgery due to advanced three vessel coronary artery disease. All patients underwent total arterial myocardial revascularization using both pedicled mammary arteries and a radial artery, with a mean of 3.6 grafts per patient. A rhomboid shaped total wall ECA and ICA sample, with a long axis of 7–9mm and a short axis of ∼1mm, was obtained by dissection during grafting maneuvers of the vessels from each patient. Reverse transcription-polymerase chain reaction (PT-PCR) was used for LOX-1 mRNA. Total mRNA (1μg) was directly extracted from ECA and ICA samples by the acid guanidium-phenol-chloroform method using RNEasy kit (Qiagen, Germany) according to the manufacturer's protocol. The extracted total RNA was reverse-transcribed using OneStep RT-PCR kit (Qiagen Japan, Tokyo Japan). Reverse –transcribed material (1.5μL) was amplified with DNA polymerase (Invitrogen, California USA) using a primer pair specific to human LOX-1. Each LOX-1 mRNA was normalized with a band of the relative internal reference GAPDH mRNA. The relative intensities of bands of interest were analyzed using Gel Doc 2000 (Bio-Rad Labs, Hercules, CA) and expressed as ratio to the GAPDH mRNA band.