Studies in Experimental Hypertension and the Renin-Angiotensin System

Blood pressure, angiotensin II and renin content were measured in unanaesthetized two-kidney, one clip hypertensive rats at 1 and 2 days, at weekly intervals up to 10 weeks and at 15 and 20 weeks after clipping. Blood pressure was elevated at 1-2 days and remained at this level until 2 weeks when there was a further progressive rise reaching a plateau at 5-6 weeks after which time hypertension was sustained up to 20 weeks. Compared with values in sham-operated rats angiotensin II and renin were initially increased at 1-2 days but were then supressed between 2 and 4 weeks to levels similar to those found in the sham-operated rats. Between 5 and 20 weeks angiotensin II and renin increased again to high levels. There was a significant correlation between angiotensin II and blood pressure in acute rats 1-2 days after clipping (p<0.05) and in chronic rats 8-20 weeks after clipping (p