Differential Stiffness between Resistance Microvessels and Conduit Arteries in the Coronary Circulation of Ossabaw Swine with Metabolic Syndrome

The aim of the current study was to determine whether coronary resistance microvessels (CRMs) undergo differential remodeling compared to coronary conduit arteries in metabolic syndrome (MetS). Ossabaw pigs were fed either normal (n=7; Lean) or atherogenic diet (n=7; MetS) for 6 months after which CRM pressure myography and intravascular ultrasound of coronary conduit arteries were performed. MetS CRMs exhibited inward hypertrophic remodeling as shown by reduced luminal diameter and increased wall thickness. Both incremental modulus of elasticity (IME, Lean: 3.6×10 6 ± 0.7×10 6 vs. MetS: 1.1×10 6 ± 0.2×10 6 , p < 0.001) and beta stiffness index (BSI, Lean: 10.3 ± 0.4 vs. MetS: 7.3 ± 1.8, p < 0.001) were decreased in MetS CRMs, while CRM distensibility was augmented (Lean: 0.1 ± 0.004 vs. MetS: 0.18 ± 0.03, p < 0.05). In contrast, BSI was increased (Lean: 4.7 ± 0.8 vs. MetS: 6.7 ± 0.3, p < 0.05) and distensibility was reduced (Lean: 0.36 ± 0.05 vs. MetS: 0.17 ± 0.01, p < 0.01) in MetS coronary conduit arteries. Molecular analysis revealed reduced col1a1/elastin and col3a1/elastin mRNA ratios in MetS CRMs, while these ratios remained unchanged in the coronary conduit arteries. These data suggest that differential remodeling between CRMs and conduit arteries may reflect differential extracellular matrix expression. Support: NIH T32HL098039 to AJT; NIH HL056046 , NCH to PAL; NIH HL062552 , UL1 RR025761 , Purina TestDiet to MS.