RENAL MEDULLA AND BRADYKININ DURING THE DEVELOPMENT OF HYPERTENSION IN SHR

1. The long-term reduction in blood pressure following ACE inhibitor t reatment in young spontaneously hypertensive rats (SHR) appears to dep end on both the kidney and bradykinin. 2. The aim of this experiment w as to examine the effects of ACE inhibition and bradykinin on renal mo rphology and blood pressure in SHR. 3. Between 6 and 10 weeks of age m ale SHR received one of four treatments: water (n = 26), ramipril (1 m g/kg per day; n = 24), ramipril (1 mg/kg per day) plus Hoe 140 (0.5 mg /kg per day; n = 25) or Hoe140 (0.5 mg/kg per day; n = 25). 4. Renal m edullary and cortical volumes were determined stereologically at 10 an d 20 weeks of age. 5. After 4 weeks of treatment, ramipril reduced the size of the renal medulla while Hoe 140 increased medullary volumes c ompared to control. Ten weeks after treatment was stopped the renal me dulla of the ramipril group had returned to normal, however, there was a persistent increase in medullary volume of both Hoe 140 treated gro ups. 6. Our results imply that bradykinin may influence the size of th e renal medulla which may have important effects on the development of hypertension in SHR.