Further Observations on Development of a Colony of Spontaneously Hypertensive Rabbits. ∗

Summary

(1) Two new generations of spontaneously hypertensive rabbits showed about the same incidence of elevated systolic pressures as their progenitors at 6 and 8 months of age, 58 and 71% respectively. At 4 months, mean systolic pressure in the 2 new generations was significantly higher than in their progenitors at same age. (2) Male rabbits of the new generations in all 3 age groups had higher mean systolic values than females and than their male or female progenitors. (3) Direct arterial pressure measurements in a group of spontaneously hypertensive rabbits showed average diastolic pressure to be 10 mm Hg higher and systolic pressure 30 mm Hg higher than in normo tensive stock rabbits. (4) Direct arterial recordings from unanesthetized animals demonstrated spontaneously hypertensive rabbits to have larger Traube-Hering waves than normotensives. (5) The presence of interstitial nephritis in normotensive as well as spontaneously hypertensive animals precludes it as an etiological factor in the development of spontaneous hypertension.