Distribution and content of renin and renin mRNA in remnant kidney of adult rat.

To determine whether kidney hypertrophy secondary to reduction of renal mass affects the intrarenal distribution and concentration of renin mRNA and its protein, adult male Sprague-Dawley rats were studied 4 wk after sham operation (Sham, n = 10), uninephrectomy (UNX, n = 14), or five-sixths nephrectomy (5/6 NX, n = 12). Left kidney weight-to-body weight ratio (x10(3)) was higher in 5/6 NX (6.6 +/- 0.2) than in UNX (4.5 +/- 0.2) or Sham (3.8 +/- 0.1) groups (P < 0.001). The percentage of juxtaglomerular apparatuses (%JGA) containing renin was lower in 5/6 NX (32 +/- 5) than in UNX (56 +/- 2, P < 0.001) or Sham (50 +/- 1, P < 0.05) groups. Renal renin mRNA concentrations (pg renin mRNA/microgram total RNA) detected by radiodensitometric renin mRNA dot-blot assay were lower in 5/6 NX (1.8 +/- 0.3) than in UNX (13.2 +/- 1) or Sham (14.2 +/- 1.1, P < 0.001). In situ hybridization histochemistry demonstrated that in all groups of rats renin mRNA was confined to the JGA. However, the hybridization signals (grains/JGA) were less intense in 5/6 NX (211 +/- 24) than in UNX (486 +/- 35) or Sham (541 +/- 40) groups (P < 0.001). Renal renin concentration (ng angiotensin I.mg protein-1.h-1) tended to be lower in 5/6 NX (20 +/- 15) than in UNX (44 +/- 7.8) or Sham (60.8 +/- 10) groups. In addition, plasma renin activity (ng.ml-1.h-1) was lower in 5/6 NX (3.8 +/- 0.6) than in UNX (8.8 +/- 1.8, P < 0.05) or Sham (14.3 +/- 2, P < 0.001) groups.(ABSTRACT TRUNCATED AT 250 WORDS)