GENETIC-CHARACTERIZATION OF NOVEL STRAINS OF RATS DERIVED FROM CROSSES BETWEEN WISTAR-KYOTO AND SPONTANEOUSLY HYPERTENSIVE RATS, AND COMPARISONS WITH THEIR PARENTAL STRAINS

Two novel strains of rats have recently been generated from hybrid cro sses of spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) r ats, The breeding pairs chosen to create these strains were initially selected on the basis of two mutually exclusive phenotypic traits, so that the rats called WKHT are hypertensive but not hyperactive, wherea s the rats called WKHA are hyperactive but not hypertensive, These str ains have been refined by inbreeding on a strict brother-sister basis for more than 25 generations, To increase usefulness of these strains, we characterized them by use of genetic methods, including DNA finger printing and simple sequence length polymorphism (SSLP) analyses, We f ound that these two novel strains are more closely related genetically to either SHR or WRY rats than the degree to which the latter two str ains are related to one another; heterozygosities of SSLP marker allel es were extremely rare in WKHA and WKHT, indicating that these strains can be considered as truly inbred (in contrast to WKY rats from two s ources); and it was almost always possible to match the SSLP marker al leles found in WKHA and WKHT rats with similarly sized alleles in the parental SHR and WKY alleles, indicating that the WKHA and WKHT strain s constitute true mixes of the genomes of SHR and WKY rats, Furthermor e, immunogenetic analyses indicated that WW and WKHT rats belonged to the RT1 I haplotype, whereas SHR and WKHA rats belonged to the k haplo type, These results extend the usefulness of WKHA and WKHT rats for fu rther genetic and physiologic studies.