Cerebral infarction after middle cerebral artery occlusion in progenies of spontaneously stroke-prone and normal rats.

A differential outcome results from rapid middle cerebral artery (MCA) occlusion in young normotensive Wistar (NW) rats as compared to the spontaneously hypertensive stroke-prone (SHRSP) rat. The SHRSP invariably infarcts; the NW usually does not. To determine if segregation at a single autosomal locus explains the difference between strains, a NW male was crossed with several SHRSP females to produce F1 rats. The segregation of the strain difference was studied in the F2 and backcrosses to the NW and SHRSP parental strains. The relative frequency of infarcting and noninfarcting animals in the segregating progenies supported a single locus recessive model of inheritance for susceptibility to infarction after sudden occlusion of the MCA. Mean infarct size was largest for SHRSP and proportional to the SHRSP gene dosage in the segregating progenies. Variation in the size of the infarct within segregating classes may be attributable to the segregation of polygenes and/or environmental influences during the initial formation of the cerebral anastomoses.