American Journal of Hypertension 2018 - Norman Pollock.pdf (536.76 kB)

Inactive Matrix Gla Protein, Arterial Stiffness, and Endothelial Function in African American Hemodialysis Patients

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journal contribution
posted on 05.03.2019 by Mary Ellen Fain, gaston kapuku, William Paulson, Celestine Williams, Anas Raed, Yanbin Dong, Marjo Knapen, Cees Vermeer, Norman K. Pollock

Abstract

BACKGROUND:

Matrix Gla protein (MGP) is a vascular calcification inhibitor dependent upon vitamin K for activation. Evidence suggests that elevated plasma inactive MGP levels (desphospho-uncarboxylated MGP, dp-ucMGP; indicating poorer vascular vitamin K status) are associated with greater cardiovascular disease (CVD) risk. Despite African Americans experiencing highest rates of kidney failure and CVD events, relationships between dp-ucMGP and CVD risk markers have not been examined in this population. We investigated vascular vitamin K status (via plasma dp-ucMGP) between African American hemodialysis (HD) patients and healthy controls, and the associations of dp-ucMGP with arterial stiffness and endothelial function in HD patients only.

METHODS:

In 37 African American HD patients and 37 age- and race-matched controls, plasma dp-ucMGP was measured by enzyme immunoassay as a marker of vascular vitamin K status. Carotid-femoral pulse wave velocity (PWV; arterial stiffness measurement) and brachial artery flow-mediated dilation (FMD; endothelial function measurement) were assessed by applanation tonometry and ultrasound, respectively, in HD patients only.

RESULTS:

Mean dp-ucMGP levels were 5.6 times higher in HD patients vs. controls (2,139 ± 1,102 vs. 382 ± 181 pmol/l, P < 0.01). Multiple linear regression, adjusting for age, sex, dialysis vintage, diabetes mellitus, CVD history, body mass index, and blood pressure, revealed that dp-ucMGP was independently related to PWV (standardized β = 0.49) and FMD (standardized β = -0.53) (both P < 0.01).

CONCLUSIONS:

Our data suggest that the higher plasma dp-ucMGP concentrations found in African American HD patients may be associated with greater arterial stiffness and endothelial dysfunction.

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16GRNT31090037

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