A mechanistic collagen recruitment model can explain passive property differences in resistance arteries from salt sensitive, fawn hooded and brown norway rats on low salt diets

Abstract

A mechanistic model for collagen recruitment and passive response was developed which predicts the stress of elastin and collagen fibers in middle cerebral arteries based on available pressure‐diameter data for salt sensitive (SS/JrHsdMcwi, n=8), fawn hooded (FHH/EurMcwi, n=11) and brown norway (BN/NHsdMcwi, n=10) male rats, all maintained on a low salt (0.4% NaCl) diet. In this model, which describes total vessel wall stress as a sum of elastin and collagen stresses, a Weibull distribution function is assumed to describe gradual recruitment of collagen fibers in the vessel wall. It was found that the peak recruitment strain parameter for collagen was relatively invariant within each rat strain based on independent analysis of the experimental data. Subsequently with the peak recruitment strain parameter fixed, the remaining parameters describing ratios of cross sectional elastin and collagen area to total vessel wall area and shape of the recruitment distribution can be determined by fitting the model to experimental data. Applying this model to SS, BN and FH rat data shows that average elastin tension is 2.91 N/m for BN, 2.9 N/m for FH and 3.2N/m for SS and average collagen tension is 49.3 N/m for BN, 76.0 N/m for FH and 86.0 N/m for SS. Therefore we can conclude that cerebral arteries of the SS rat have stiffer passive properties than those of FH and BN rats, even before onset of any difference in hypertensive phenotype.