Background:Segregation studies using genomic polymorphisms on F2progeny obtained from hypertensive rat models showed that a putative hypertensive gene is located close to the angiotensin converting enzyme (ACE) gene. However, it was suggested that additional major genes should contribute to the pathogenesis of hypertension.Methods:F2rats were obtained from stroke-prone spontaneously hypertensive rats (SHRSP) and Wistar-Kyoto (WKY) rats of Izumo colony. Blood pressure was measured with a photoelectronic oscillometric tail-cuff method before and during salt loading. Genomic DNA was extracted from livers and digested with Haelll or Rsal. DNA fingerprinting was performed with 26 32P-labelled human variable number of tandem repeats markers.Results:Eighty-seven fingerprint bands polymorphic between SHRSP and WKY were obtained. When the distribution of these bands in the F2progeny was studied, one fingerprint band (1/MCT96.1) showed a distorted distribution between the high- and low-blood pressure subpopulations of the F2rats, suggesting that the band cosegregated with blood pressure. When blood pressure was compared between the F2rats with [( + ) rats] and without [( - ) rats] the 1/MCT96.1 band, it was found that (-) rats had significantly higher basal and salt-loaded blood pressures than ( + ) rats. The 1/MCT96.1 locus was also shown to have no positive linkage with the ACE locus.Conclusion:The present study showed that examination of the allele distribution between subpopulations with extreme phenotype can be used in the screening of loci cosegregating with blood pressure. Furthermore, a locus not in the ACE region, showing cosegregation with blood pressure in F2progeny from SHRSP and WKY rats, was found.