title: Compromised bioavailable IGF-1 of black men relates favourably to ambulatory blood pressure: The SABPA study.
abstract: OBJECTIVE
  Insulin-like growth factor-1 (IGF-1) has potent endothelial-protective, anti-platelet and anti-thrombotic activities, and also exerts mitogenic and proliferatory actions on vascular smooth muscle cells. Conflicting reports exist regarding the role of IGF-1 in vascular protection and atherogenesis. We therefore investigated the relationships of ambulatory blood pressure (BP) and carotid intima-media thickness (cIMT) with a range of components of the IGF-1 axis in a bi-ethnic population.
  
  
  METHODS
  We included black (N = 86) and white (N = 101) men and measured growth hormone, total IGF-1, insulin-like growth factor binding protein-3 (IGFBP-3), and pregnancy-associated plasma protein-A (PAPP-A) levels.
  
  
  RESULTS
  Ambulatory BP was almost 10 mmHg higher in black men (137/88 mmHg versus 128/80 mmHg; both p < 0.001), accompanied by an adverse profile of the IGF-axis for all measured components (all p < 0.01), including reduced bioavailable IGF-1 (IGF-1/IGFBP-3; p = 0.006) and tissue IGF-1 accessibility index as represented by IGF-1.PAPP-A/IGFBP-3 (p < 0.001). Single, partial and multiple regression analyses confirmed an independent inverse association between ambulatory systolic BP and bioavailable IGF-1 in black men (R(2) = 0.24; β = -0.22; p = 0.035). cIMT was similar in the ethnic groups (p = 0.34), and was negatively associated with bioavailable IGF-1 in white men (R(2) = 0.42; β = -0.17; p = 0.039) prior to adjustment for γ-glutamyl transferase (R(2) = 0.45; β = -0.10; p = 0.25).
  
  
  CONCLUSIONS
  Ambulatory systolic BP is inversely related to bioavailable IGF-1 in black men who displayed low IGF-1 concentrations. An inverse relation was found between cIMT and IGF-1 in white men, which disappeared after correction for γ-glutamyl transferase - opposing reports of a detrimental role of IGF-1 in the early stages of atherogenesis.
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa. Electronic address: Alta.Schutte@nwu.ac.za.
authors: A E
authors: AE
authors: Schutte
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: R
authors: R
authors: Schutte
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: W
authors: W
authors: Smith
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: H W
authors: HW
authors: Huisman
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: C M C
authors: CM
authors: Mels
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: L
authors: L
authors: Malan
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: C M T
authors: CM
authors: Fourie
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: N T
authors: NT
authors: Malan
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: J M
authors: JM
authors: Van Rooyen
authors: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors: R
authors: R
authors: Kruger
authors: Cardiovascular and Thoracic Department, Sapienza University of Rome, Italy.
authors: E
authors: E
authors: Conti
mesh_terms: D000328:Adult; D050197:Atherosclerosis / Q000097:blood; D001682:Biological Availability; D044383:Black People; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory; D059168:Carotid Intima-Media Thickness; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D011266:Pregnancy-Associated Plasma Protein-A / Q000378:metabolism; D044465:White People
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D007334:Insulin-Like Growth Factor I; D011266:Pregnancy-Associated Plasma Protein-A
keywords: African; Ambulatory blood pressure; Atherosclerosis; Black; Growth hormone; Insulin-like growth factor binding protein-3; Insulin-like growth factor-1; Pregnancy-associated plasma protein-A