Hypertension in Page (cellophane-wrapped) kidney is due to interstitial nephritis

Cellophane wrapping of the kidneys (Page kidney) induces perinephrits and hypertension, assumed to be due to renal ischemia resulting from parenchymal compression by the fibrous hull surrounding the kidneys. We investigated if interstitial nephritis, rather than plasma angiotensin activity, played a role in the development of hypertension in the Page kidney model.

We followed for 7 weeks rats with bilateral cellophane wrapping of the kidneys that received 20 mg/kg/day of the immunosuppressive antiproliferative drug mycophenolate mofetil (MMF) (two-kidney wrap/MMF) (N = 10) or vehicle (two-kidney wrap) (N = 10), and sham-operated rats (N = 10).

The two-kidney wrap group had progressive increment in blood pressure, inflammatory damage occupying 25% to 50% of the renal tubulointerstitial region and increased number of angiotensin II-positive cells, angiotensin II content, and oxidative stress in the kidney. MMF treatment prevented the development of hypertension and renal inflammation without modifying the perinephritic hull or the increment it induced in the intrarenal pressure. The plasma levels of angiotensin II were similar in the two-kidney wrap group, the two-kidney wrap/MMF group and the sham-operated animals and unchanged from baseline, despite the blood pressure increase in the two-kidney wrap group.

Our results indicate that renal wrap hypertension is unrelated to plasma angiotensin II levels and related to the inflammatory damage caused by the external compression of the kidney.