Variability of Arterial Pressure in Normotensive and Spontaneously Hypertensive Rats 1

Summary

Daily indirect systolic pressure was measured, without anesthesia, for 3 months to determine the relationship between variability and height of pressure in individual normotensive and spontaneously hypertensive (SHR) rats. Average systolic pressure correlated with its standard deviation indicating the higher the pressure the greater its variability. The empiric dividing line for hypertension in the rat of 150 mm Hg was reexamined and found appropriate. No SHR rat had an average weekly pressure less than 150 mm Hg and 28% of the controls had at least 1 weekly average above 150 mm Hg; we have termed these rats as “borderline hypertensives.” Daily variability of pressure of borderline hypertensives was greater than the remaining controls. Therefore, borderline hypertensives have greater lability of arterial pressure.

The authors gratefully acknowledge the statistical advice of Drs. John McCoy (of the Veterans Administration Southern Research Support Center, Little Rock, AR) and Donald Parker (of the University of Oklahoma Medical Center), the technical assistance of Mrs. Janice Pfeffer and Mr. Philip Barrett, and the secretarial work of Mrs. Irene Smith.