Effects of graded renal artery constriction on blood pressure, renal artery pressure, and plasma renin activity in Goldblatt hypertension

W R Murphy, T G Coleman, T L Smith, K A Stanek
1984 Hypertension  
One-kidney, one clip (1K1C) and two-kidney, one clip (2K1C) Goldblatt hypertension was produced in rats by placing 0.30, 0.25, or 0.20 mm silver clips on the left renal artery. Mean arterial pressure (MAP) and plasma renin activity (PRA) were measured in conscious rats 24 to 28 days after clipping. The MAP in control rats (n = 38) was 116 ± 1 mm Hg (mean ± SEM). The 0.30, 0.25, and 0.20 mm clips produced MAPs of 133 ± 2,161 ± 5, and 189 ± 5 mm Hg, respectively, in 1K1C rats, and 123 ± 2, 129 ±
more » ... and 123 ± 2, 129 ± 3, and 172 ± 5 mm Hg in 2K1C rats (n = 17-20). When 1K1C and 2K1C groups were compared, MAP was significantly greater in 1K1C rats at all clip sizes. No treatment group's PRA was different than control (4.8 ± 0.4 ng Al/ml/hr), except for the 0.20 mm 2K1C rats (16.2 ± 3.1 ng Al/ml/hr). Renal artery pressure (RAP) was measured in another series of experiments and was not different from control in all but the 0.20 mm 1K1C rats. With identical clip sizes, 2K1C rats showed smaller pressure gradients than 1K1C across the clips: 0.30 mm, 8.5 ± 1.7 vs 10.7 ± 1.9 mm Hg; 0.25 mm, 16.5 ± 1.2 vs 42.1 ± 7.5 mm Hg; 0.20 mm, 51 ± 5.3 vs 79.1 ± 5.7 mm Hg (n = 8-12). Therefore, both the increase in MAP and the pressure gradient across the clip were greater in the 1K1C rats at every clip size. In total, these data indicate that RAP is controlled to maintain a normal pressure in both models of Goldblatt hypertension. In 1K1C rats, RAP is normalized in conjunction with a rise in MAP. In the 2K1C rats, we propose that an increase in the clipped kidney's renal vascular resistance, secondary to renal atrophy, acts to increase RAP without hypertension. With severe renal artery clipping in 2K1C animals, renal atrophy alone may not fully restore RAP; in this case the hypertension is required to normalize RAP. (Hypertension 6:68-74, 1984) KEY WORDS • Goldblatt hypertension • two-kidney, one clip renal artery pressure * one-kidney, one clip and then select only those rats with pronounced hypertension. The 2K1C animals that do develop significant hypertension often enter into a malignant phase of hypertension; 3 this transition to malignant hypertension does not occur as readily in 1K1C animals. Renal artery constriction has different effects on the renin-angiotensin system in each of the two Goldblatt hypertension models. Initially following renal artery constriction, plasma renin activity (PRA) increases in the 1K1C model, but returns to normal in the established phase of hypertension. 4 Blockade of the reninangiotensin system does not prevent 1K1C hypertension in the rat, but does affect the final level of hypertension by 10 to 15 mm Hg.' 2 In 2K1C animals, PRAs are also acutely elevated following renal artery constriction." Some investigators have found that PRAs remained elevated in the chronic phase of 2K1C hypertension, 1 -2 -8 while others have reported that PRAs returned to normal. 6 7 The importance of the renin-angiotensin system in 2K1C Goldblatt hypertension is underscored by the fact that chronic converting-68 by guest on July 19, 2018 http://hyper.ahajournals.org/ Downloaded from
doi:10.1161/01.hyp.6.1.68 pmid:6363282 fatcat:h727um4nfrfejortvzvg2br6vm