To determine whether leukocytes express the angiotensinogen gene, we subjected circulating rat leukocytes and murine bone marrow cells to Northern blot analysis and hybridization with homologous angiotensinogen complementary DNA. Angiotensinogen messenger RNA sequences were detected in circulating adult rat leukocytes, in murine-irradiated and nonirradiated bone marrow stromal cells, and in an adherent stromal cell line (preadipocyte). Western blot analysis of rat leukocyte homogenate showed that rat leukocytes contain two main angiotensinogen isoforms with approximate molecular weights of 46.5 and 53.9 kd. Synthesis and release of angiotensinogen protein by rat leukocytes was confirmed by immunoprecipitation of radiolabeled angiotensinogen from cell lysate and media of rat leukocytes that were metabolically labeled with M S-L-methionine. In addition, the angiotensinogen protein present in media of rat leukocytes was enzymatically cleaved by hog renin, resulting in generation of angiotensin I (305±47 pg angiotensin I per milliliter of media per hour). We conclude that circulating rat leukocytes express the angiotensinogen gene and synthesize and release angiotensinogen with the capability to generate angiotensin. Expression of angiotensinogen by leukocytes may provide a mobile angiotensingenerating system of potential importance in the regulation of local inflammatory responses, tissue injury (i.e., myocardial infarction), and arterial hypertension.

Angiotensin is generated within the kidney, but the precise loci for the formation of angiotensin I (ANG I) and angiotensin II (ANG II) have not been demonstrated. We performed electron microscopy immunocytochemistry in kidney sections of 10-day-old (newborn) and adult Wistar-Kyoto (WKY) rats using specific antibodies to renin, ANG I, ANG II, and angiotensinogen (AO). Renin, ANG I, ANG II, and AO were present in juxtaglomerular (JG) cells. Renin was largely confined to cytoplasmic granules; ANG I and ANG II were colocalized to these granules but also were present in the cytoplasm; AO was distributed throughout the cytoplasm. AO also was present in a renal cortical distribution in proximal tubular cells. Northern blot analysis demonstrated AO mRNA in total kidney and liver but not in renal microvessels. Using the reverse hemolytic plaque assay, we demonstrated release of ANG I and renin from individual renocortical cells of adult WKY rats. Under control conditions, the number of releasing cells was 11 +/- 1 for ANG I and 10 +/- 1 for renin. Addition of rat renin inhibitor (RI) (1 x 10(-5) M), which inhibited renin activity in the medium from 37 to 9 pg ANG I.ml-1.h-1, did not alter ANG I plaque number. Addition of rat AO increased ANG I plaque number to 17 +/- 2 (P less than 0.05). Incubation with both RI and AO prevented the increase in ANG I plaque number obtained with AO alone. Enalapril treatment (7 days; n = 5) increased the number of plaque-forming cells to 22 +/- 2 for ANG I (P less than 0.0005) and to 39 +/- 7 for renin (P less than 0.001). The results suggest an intracellular location for AO and angiotensin and release of renin and ANG I by renal cortical cells and suggest that released angiotensin is produced intracellularly and that secretion of ANG I is augmented by converting enzyme inhibition.

Nephropathic cystinosis, a rare autosomal recessive storage disease characterized by intracellular storage of free cystine due to a defect in lysosomal cystine transport, is the most common cause of Fanconi syndrome in childhood. Although manifestations of extrarenal organ involvement during the course of the disease are diverse, the spectrum of gastrointestinal (GI) problems has not yet been examined. In responses to a questionnaire from 70 (35%) of the 200 registered members of the Cystinosis Foundation, we found that GI symptoms are more common, more diverse, and occur at a younger age in patients with cystinosis than previously recognized. Ninety-three percent of interviewed subjects had GI symptoms at initial presentation, and the overall lifetime prevalence of GI problems in this group was 100%. Thirty percent have received gastric/jejunal tube feedings, and 7% required continuous or intermittent total parenteral nutrition. Fifty percent have been formally tested for GI abnormalities, and among these 77% have documented functional abnormalities (reflux/dysmotility, pseudo-obstruction, swallowing dysfunction). Early recognition and aggressive therapy of GI problems in cystinotic patients may ameliorate or prevent the development of disabling symptoms.

To determine whether Cyclosporine A (CsA) alters the intrarenal expression of the renin and type 1 angiotensin II receptor genes, male adult Sprague-Dawley rats were given 25 mg/kg/day CsA s.c. for three weeks (CsA, N = 20) and were compared to pair-fed vehicle treated rats (Con, N = 20). The intrarenal distribution of renin and its mRNA was assessed by immunocytochemistry and in situ hybridization. In addition, kidney renin and type 1 angiotensin II (AT1) receptor mRNA levels were determined by Northern blot analysis. The percentage of juxtaglomerular apparatuses containing renin was higher in the CsA (84 +/- 5.5%) than in the Con (61 +/- 6.7%) group, (P < 0.05). The length of renin immunostaining along afferent arterioles was higher in the CsA (74 +/- 4.5 microns) than in the Con (37 +/- 5.1 microns) group, (P < 0.05). In contrast, neither renin mRNA levels nor its intrarenal distribution were altered by chronic CsA administration. Kidney AT1 receptor mRNA levels were lower in the CsA group than in the Con group. We conclude that chronic CsA: (1) induces recruitment of renin containing cells along the afferent arteriole, (2) causes no changes in intrarenal renin mRNA levels or distribution, suggesting that post-transcriptional events may be responsible for the persistence and/or uptake of renin by the preglomerular vasculature, (3) promotes a downregulation of AT1 receptor gene in the kidney, suggesting that local angiotensin II may control AT1 receptor gene expression by a negative feedback.