HIGH BLOOD-PRESSURE AND METABOLIC DISORDERS ARE ASSOCIATED IN THE LYON HYPERTENSIVE RAT

Objective: A large population of F2 rats, obtained from a cross betwee n male Lyon hypertensive (LH) rats and female Lyon normotensive (LN) r ats, was studied in order to assess the relationship between increased body weight, hyperlipidaemia and high blood pressure which characteri ze LH rats. Methods: Mean arterial pressure (MAP) was recorded in male , conscious, freely moving LH, LN, F1 and F2 rats aged 30 weeks. Plasm a total cholesterol, high-density lipoprotein-, low-density lipoprotei n- and very low-density lipoprotein-cholesterol, phospholipids, trigly cerides, insulin and glucose were measured. Results: In the F2 cohort it was observed that high MAP was a recessive trait that depends on se veral genes and was unrelated to body weight. The left ventricular wei ght, corrected for tibia length, was correlated with MAP. Plasma total and high-density lipoprotein-cholesterol and phospholipids concentrat ions were lower in the F1 rats than in the LN rats, suggesting an over dominance of the LN alleles. In the F2 rats MAP was related to total, high-density lipoprotein- and low-density lipoprotein-cholesterol. Pla sma triglycerides, insulin and the insulin:glucose ratio, which were h igher in the LH rats than in the LN rats, were also correlated with MA P in the F2 cohort. Using stepwise multiple regression analysis, MAP r emained correlated with plasma total cholesterol, insulin and the insu lin: glucose ratio, but not with triglycerides. Conclusions: Hypertens ion in LH rats' is a recessive trait that is independent of body weigh t. In addition, the cosegregation of blood pressure with plasma choles terol and, to a lesser degree, with insulin levels, which was observed in the present study provides the first direct evidence that these ph enotypes are associated and are not due simply to genetic drift in the Lyon model.