GENETIC-FACTORS REGULATE THE RISE IN BLOOD-PRESSURE IN F2 GENERATION CROSSED BETWEEN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS AND WISTAR-KYOTO RATS

1. There was no significant difference between the systolic blood pressure (SBP) of offspring derived from SHRSP mother and WKY father and the SBP of offspring derived from WKY mother and SHRSP father at the developing stage (5-13 weeks of age). 2. The degree of genetic determinations of SBP in stroke-prone spontaneously hypertensive rat (SHRSP) at 5, 7, 10 and 13 weeks of age, determined by genetic crosses between SHRSP and WKY, was 73.9, 70.8, 50.2 and 55.3% respectively. 3. Significant correlations between SBP at 5 and 7 weeks, 7 and 10 weeks, 10 and 13 weeks, also at 5 and 13 weeks of age in F2 generation crossed between SHRSP and WKY were observed. SBP falling at or above the 80th percentile group in F2 generation at 5 weeks of age were constantly higher than SBP falling at or below the 20th percentile group from 7 weeks of age onwards. 4. These results indicate that there exists 'tracking phenomenon of SBP in SHRSP' and that genetic factors regulate the rise in SBP. Tracking of SBP in F2 generation gives us new methodological insight into hypertensive mechanism in SHR.