[Plasma renin activity and angiotensin converting enzyme of renal brush borders]

The present experiment was undertaken to examine the relationship between plasma renin activity and the concentration of angiotensin converting enzyme (ACE) in plasma and renal brush border of Wistar Kyoto rats. Different experimental models known to have opposite effects on plasma renin activity were used: changes in salt intake, the deoxycorticosterone acetate (DOCA) and DOCA-salt models and the two-kidneys one clip (2K1C) model. Two weeks after the start of these experimental series, the rats were killed. At this time, blood pressure did not differ from control group, even in the 2K1C and DOCA-salt groups. As expected, PRAs were highest in the 2K1C and depleted salt groups and lowest in the DOCA, DOCA-salt and high salt groups. No relationship between this wide variation in PRA and change of ACE activity in both plasma and renal brush border could be observed. In the plasma, ACE activity in sodium-depleted rats was slightly decreased whereas no change occurred in the other models. In the kidney, DOCA treatment led to increased ACE activity in the brush border only if the animals were maintained on a high salt intake. DOCA or NaCl alone failed to have this effect. In the 2K1C model, the clipped kidneys exhibited increased brush border ACE activity whereas the unclipped kidneys did not show any significant variation in ACE activity, when compared to sham operated rats. In summary, on one hand these findings show that variations in ACE activity were linked neither to hypertension nor to changes in PRA.(ABSTRACT TRUNCATED AT 250 WORDS)