Strain differences in neointimal hyperplasia in the rat

We performed an initial screen of 11 rat strains by use of a standard ballo on injury to the left iliac artery to observe whether genetically determine d differences existed in the development of neointimal hyperplasia. Neointi mal hyperplasia was assayed 8 weeks after the vascular injury on coded micr oscopic sections. Statistically significant differences in the percentages of the vascular wall cross-sectional areas composed of intima (percentage i ntima) secondary to neointimal hyperplasia were noted among the different r at strains (P<0.02), with the Brown-Norway (BN), Dark Agouti, and Milan nor motensive strain rats having the highest and the spontaneously hypertensive rats (SHR) having the lowest percentages of intima. In a separate experime nt, F-1 hybrids of SHRXBN strains and parental BN and SHR underwent the vas cular injury, and the parental strains again showed a statistically signifi cant difference from one another in the mean percentage of intima (P<0.0001 ) The F-1 hybrids showed an average percentage of intima intermediate betwe en those of the parental strains. The average lumen size of the injured BN vessels were significantly smaller than that of the noninjured control vess els (P=0.044), but this significance disappeared when the circular areas of these vessels were calculated without taking neointimal growth into consid eration (P=0.649). These results provide the groundwork for a genetic linka ge analysis to identify the genes that influence the development of neointi mal hyperplasia after vascular injury.