Expression of neuronal nitric oxide synthase and renin in dysplastic kidneys of young dogs

Abstract

Renin and neuronal nitric oxide synthase in the kidney control the renin-angiotensin and tubuloglomerular feedback systems. The present study investigated the expression of renin and neuronal nitric oxide synthase in the dysplastic kidneys of three young dogs. Renin-immunoreactivity, which occurs in the juxtaglomerular and tubular cells of dysplastic kidneys, did not differ from that in the normal kidneys of young dogs. Macula densa cells in the normal kidneys showed neuronal nitric oxide synthase -immunoreactivity, but those in the dysplastic kidneys showed no apparent signals. This observation may be correlated with the pathological mechanisms of renal failure in young dogs.

Keywords: chronic kidney disease; dysplastic kidney; immunohistochemistry; neuronal nitric oxide synthase; renin.

Fig. 1.

Immunohistochemistry for renin in a dysplastic canine kidney. A: Renin-positive signals were observed in the juxtaglomerular cells near the vascular poles and some glomerular cells (arrows). Bar: 50 µm. B: A different region of the section shown in panel A. Tubules in the unidentified nephron segment show renin-immunoreactivity. Bar: 50 µm.

Fig. 2.

Immunohistochemistry for neuronal nitric oxide synthase in a dysplastic kidney. The tubular cell macula densa region (arrow) shows no apparent positive immunoreactivity. Bar: 50 µm.

Fig. 3.

Immunohistochemistry for neuronal nitric oxide synthase in a dysplastic kidney. In this case, many dilated and flattened tubules show clear positive signals. Bar: 100 µm.

Fig. 4.

Immunohistochemistry for neuronal nitric oxide synthase in a normal kidney from a young dog. The neuronal nitric oxide synthase-positive signals were observed in the macula densa regions (arrows) of the thick ascending limbs. Bar: 50 µm.