Possible relationship between insulin resistance and remnant-like lipoprotein particles in coronary endothelial dysfunction.
BACKGROUND
High insulin resistance and elevated remnant lipoprotein levels both correlate with impaired coronary vascular endothelial function. Hyperinsulinemia induces abnormalities of lipid metabolism. However, the correlation among insulin resistance, remnant lipoproteins, and endothelial function has not been clinically elucidated.


OBJECTIVE
This study was designed to elucidate the correlation among insulin resistance, remnant lipoproteins, and acetylcholine (ACh)-induced coronary artery response.


METHODS
Forty-nine patients suspected of having ischemic heart disease, but without angiographically significant atherosclerotic coronary artery disease, underwent an ACh provocation test. Fasting venous blood was taken early in the morning on the day coronary angiography was performed. The insulin resistance index (IR) was determined from fasting plasma glucose and insulin concentrations, using the homeostasis model assessment (HOMA). Serum levels of remnant-like lipoprotein particle cholesterol (RLP-C) were measured.


RESULTS
Homeostasis model assessment IR was significantly higher (3.65 +/- 1.38 vs. 0.75 +/- 0.14, p < 0.05) and log-transformed HOMA (Log HOMA) was even more significantly higher (0.20 +/- 0.12 vs. -0.29 +/- 0.08, p < 0.001) in the ACh-positive group (n = 23) than in the ACh-negative group (n = 26). The serum RLP-C level was also higher in the ACh-positive group than in the ACh-negative group (4.37 +/- 0.63 vs. 2.52 +/- 0.18 mg/dl, p < 0.01). Log HOMA and RLP-C levels correlated with each other (R = 0.54, p < 0.001). Multiple regression analysis indicated that only the RLP-C level was a dependent predictor of Log HOMA in various lipid profiles.


CONCLUSIONS
Both high insulin resistance and elevated remnant lipoprotein levels correlated and might have a crucial role in the impairment of coronary vascular endothelial function, even in patients without angiographically significant coronary artery disease.
Inoue
Teruo
T
Department of Cardiology, Koshigaya Hospital, Dokkyo University School of Medicine, Saitama, Japan. inouet@dokkyomed.ac.jp
Uchida
Toshihiko
T
Kamishirado
Hirotoshi
H
Sakuma
Masashi
M
Sakai
Yoshihiko
Y
Takayanagi
Kan
K
Hayashi
Terumi
T
Morooka
Shigenori
S
D000109:Acetylcholine; D001786:Blood Glucose / Q000032:analysis; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D017023:Coronary Angiography; D003331:Coronary Vessels / Q000187:drug effects / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005215:Fasting / Q000097:blood; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D014665:Vasodilator Agents
D001786:Blood Glucose; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D007328:Insulin; D014665:Vasodilator Agents; D000109:Acetylcholine