High lipoprotein(a) levels and small apolipoprotein(a) sizes are associated with endothelial dysfunction in a multiethnic cohort.
OBJECTIVE
This study sought to determine the effect of lipoprotein(a), or Lp(a), levels and apolipoprotein(a), or apo(a), sizes on endothelial function and to explore ethnic differences in their effects.


BACKGROUND
Although high levels of Lp(a) have been shown to confer increased cardiovascular risk in Caucasians, its significance in non-Caucasian populations is uncertain. The pathogenic role of the apo(a) component of Lp(a) is also unclear.


METHODS
The relationship of Lp(a) levels and apo(a) sizes to endothelial function was examined in a multiethnic cohort of 89 healthy subjects (age 42 +/- 9 years; 50 men, 39 women) free of other cardiac risk factors. Endothelium-dependent, flow-mediated dilation (FMD) and endothelium-independent, nitrate-induced dilation (NTG) were assessed by ultrasound imaging of the brachial artery.


RESULTS
Plasma Lp(a) levels were lowest in Caucasians (18.3 +/- 21.1 mg/dl, n = 40); intermediate in Hispanics (30.2 +/- 30.5 mg/dl, n = 21); and highest in African Americans (68.8 +/- 46.0 mg/dl, n = 28). Lipoprotein(a) levels were found to correlate inversely to FMD (r = -0.33, p < 0.005) but not to NTG (r = 0.06, p = 0.60). This association remained significant after adjusting for gender (p = 0.002). In addition, subjects with small apo(a) size of <or=22 kringle 4 repeats had significantly lower FMD than those with large apo(a) (2.23 +/- 2.37% vs. 6.26 +/- 4.29%, p < 0.0001), irrespective of Lp(a) levels.


CONCLUSIONS
These findings support an independent role of Lp(a) in atherogenesis, an effect that is particularly evident in African Americans. The proatherogenic property of Lp(a) can be attributed in part to its apo(a) component.
Wu
Henry D
HD
Department of Medicine, Columbia University, New York, New York 10032, USA. hdw1@columbia.edu
Berglund
Lars
L
Dimayuga
Clarito
C
Jones
Jeffery
J
Sciacca
Robert R
RR
Di Tullio
Marco R
MR
Homma
Shunichi
S
D000328:Adult; D001741:Black or African American; D001053:Apolipoproteins / Q000032:analysis*; D053241:Apoprotein(a); D001916:Brachial Artery / Q000503:physiopathology; D004108:Dilatation, Pathologic / Q000503:physiopathology; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D017270:Lipoprotein(a) / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D014463:Ultrasonography; D014652:Vascular Diseases / Q000208:ethnology* / Q000503:physiopathology; D044465:White People
D001053:Apolipoproteins; D017270:Lipoprotein(a); D053241:Apoprotein(a)