P6 ARTERIAL STRUCTURE AND COAGULATION IN AGEING NAKED MOLE RATS

Abstract

Vascular stiffening and a prothrombotic state consistently increase with age. Naked mole rats (NMRs) among rodent species have a maximum lifespan exceeding 30 years. Arterial stiffness assessed by pulse wave velocity and arterial pressure have been shown not to increase with age in NMRs (Grimes et al. AJP). The objective of this work was to study the relation between functional and structural arterial changes and plasma thrombin generation changes in young (2-year-old) and adult (9-year-old) NMRs. Collagen and elastin contents, vascular smooth muscle cell density and intimal thickening have been analyzed in the thoracic aorta, whereas plasma thrombin generation was assessed by calibrated automated thrombography associated with dosage of coagulation factors and endothelial markers.Our results showed no difference in collagen, elastin and vascular smooth muscle cell (VSMC) content between 2 (n = 5) and 9-year-old (n = 5) NMRs. There was no elastin degradation nor intimal thickening in NMRs at 9-years-old compared to 2-years-old. We showed no increase in plasma thrombin generation up to 9 years of age and no change in coagulant fibrinogen and factor VIII both known to increase normally with age. The expression of Endothelial Protein C Receptor (EPCR) and Thrombomodulin were similar at both ages. In conclusion, young and adult NMRs do not show structural changes of the vascular wall in accordance with the absence of arterial stiffening. The conservation of an intact structure of the vascular wall and no change in endothelial markers during the first third of lifetime is compatible with the lack of a prothrombotic state.