Original Article

Journal of Human Hypertension (2006) 20, 867–873. doi:10.1038/sj.jhh.1002015; published inline 6 April 2006

Collagen type-I degradation is related to arterial stiffness in hypertensive and normotensive subjects

M McNulty1, A Mahmud1,2, P Spiers2 and J Feely1,2

  1. 1Department of Pharmacology and Therapeutics, St James's Hospital, Dublin, Ireland
  2. 2Trinity College Dublin and Hypertension Clinic, St James's Hospital, Dublin, Ireland

Correspondence: Dr A Mahmud, Department of Pharmacology and Therapeutics, Trinity College Dublin and Hypertension Clinic, Trinity Centre for Health Sciences, St James's Hospital, Dublin 8, Ireland. E-mail: mahmuda@tcd.ie

Received 1 February 2006; Accepted 14 February 2006; Published online 6 April 2006.

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Abstract

Although arterial stiffness is an independent cardiovascular risk factor associated with both aging and hypertension, relatively little is known regarding the structural changes in the vessel wall that occur with vessel stiffening. We determined if collagen type-I metabolism is related to arterial stiffening in both hypertensive and normotensive subjects. Arterial stiffness was assessed by aortic pulse wave velocity (PWV) and augmentation index (AIx) in 46 subjects (48.7plusminus2 years, 32 hypertensives) and related to circulating markers of collagen type-I turnover. Collagen synthesis was assessed by the measurement of carboxy-terminal peptide of procollagen type-I (PIP) and collagen degradation by the measurement of carboxy-terminal telopeptide of collagen type-I (ICTP), by quantitative immunoassay. Matrix metalloproteinase-1 (MMP-1) and the tissue inhibitor of metalloproteinase-1 (TIMP-1) were also quantified by immunoassay. The ratio of collagen type-I synthesis to degradation was negatively correlated with both PWV (P<0.05) and AIx (P<0.05), whereas plasma MMP-1 levels displayed a positive correlation with both PWV (P<0.01) and AIx (P<0.01), after adjustment for age and mean arterial pressure. The relationship between collagen type-I turnover and arterial stiffness was similar in both the normotensive and hypertensive subjects. Although circulating markers of collagen synthesis were increased in the hypertensive subjects, this was not related to arterial stiffness. Collagen type-I degradation is increased in relation to collagen type-I synthesis in subjects with stiffer arteries. Matrix metalloproteinase-1, the enzyme responsible for collagen type-I degradation, is positively related to both large elastic and muscular artery stiffness in normotensive and hypertensive subjects.

Keywords:

arterial stiffness, collagen turnover, matrix metalloproteinases, pulse wave velocity

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