Rats harboring the mouse Ren-2 transgene develop hypertension despite low levels of plasma renin activity. We tested the hypothesis that these rats exhibit an increase in vascular angiotensin formation caused by the presence of the transgene. We measured the release of angiotensins I and II from isolated perfused hindquarters by high-performance liquid chromatography and radioimmunoassay. Female rats heterozygous for the transgene had significantly elevated mean arterial pressure compared with control rats (189.3±9.5 versus 110.0±5.4 mm Hg, p<0.05). Plasma angiotensin II was significantly decreased in transgenic rats. Transgenic rat hindquarters released more angiotensin I (121±37 versus 39±12 fmol/30 min, n=7 each) and more angiotensin II (210±21 versus 62±12 fmol/30 min,/?<0.05, n-1 each) than control rat hindquarters. Captopril increased angiotensin I release and decreased angiotensin II values in both transgenic and control rat hindquarters. Bilateral nephrectomy 24 hours before hindquarter perfusion greatly reduced angiotensin release from control rat hindquarters but not from transgenic rat hind limbs. We also tested for the presence of Ren-2 messenger RNA in mesenteric and aortic tissue by RNase protection assay and Northern blot analysis. We found that Ren-2 messenger RNA was present in mesenteric and aortic tissue of transgenic but not of control rats. We conclude that the Ren-2 transgene is expressed in vascular tissue of transgenic rats and may be responsible for substantial increases in vascular angiotensin formation. (Hypertension 1992; 19:687-691) KEY WORDS • transgenic animals • renin • hind limb • converting enzyme inhibition R ecently, Mullins et al 1 were successful in producing rats transgenic for the mouse Ren-2 gene. These rats develop severe hypertension; however, they exhibit low, rather than elevated, plasma levels of renin and circulating angiotensin II (Ang II) despite the expression of the Ren-2 gene in several tissues.1 Nevertheless, the hypertension in these rats is readily responsive to low doses of angiotensin converting enzyme inhibitors.1 However, no evidence has been published that Ang II production is increased in these animals.During the past decade, attention has been drawn to local renin and angiotensin formation. Such systems have been described in the brain, heart, adrenal gland, and walls of blood vessels.2 " 5 However, the role of local Ang II production in the regulation of vascular tone remains unclear. We and others have used the isolated perfused rat hindquarter to demonstrate the activity of the vascular renin system by measuring local formation of angiotensin peptides. 5 -7 In the current study, we tested the hypothesis that rats transgenic for the mouse Ren-2 gene exhibit an increased formation of angiotensin peptides within the walls of blood vessels. We examined angiotensin release from isolated perfused rat hindquarters and demonstrated the expression of the transgene within the vessels of these rats. Our results provide direct evidence for increased blood...

1 Features of glomerulonephritis are expression of the inducible form of NO synthase (iNOS) as well as expression of the secretory group IIA-phospholipase A 2 (sPLA 2 ) in mesangial cells. Interleukin 1b (IL-1b) induces both enzymes with a similar time course resulting in an increase in nitrite production and sPLA 2 -IIA activity. In this study we investigated the relationship between the formation of NO and sPLA 2 -IIA induction in rat renal mesangial cells. 2 Incubation of mesangial cells with the NO-donor, spermine-NONOate, for 24 h induced sPLA 2 -IIA mRNA expression and activity, whereas S-nitroso glutathione alone had only a small stimulatory e ect. Stimulation of cells with IL-1b caused a marked increase in sPLA 2 -IIA mRNA and activity that were potentiated 3 fold by both NO donors. 3 Coincubation of cells with IL-1b and the NOS inhibitor, L-N G monomethylarginine (L-NMMA), caused a dose-dependent inhibition of cytokine-induced sPLA 2 -IIA mRNA expression and activity. 4 sPLA 2 -IIA activity was not stimulated by 8-bromo-cyclic GMP indicating that NO-induced sPLA 2 -IIA induction is independent of cyclic GMP-mediated signal transduction. 5 These data show that NO contributes to the expression by cytokines of sPLA 2 -IIA and establishes a novel type of interaction between iNOS and sPLA 2 -IIA in mesangial cells. This cross-talk between in¯ammatory mediators may help to promote and sustain an in¯ammatory state in the kidney.

We developed a novel method to stimulate the sympathetic innervation of the isolated, perfused rat hind limb to investigate whether a subpressor concentration of angiotensin II (Ang II) facilitates noradrenergic transmission in the vascular bed to skeletal muscle. We electrically stimulated the lumbar sympathetic trunk while perfusing the preparation with artificial medium. Seventy-five percent of the resulting frequency-dependent increases in perfusion pressure were mediated by

1 CGP-43182 has been described as a potent inhibitor of group IIA secreted phospholipase A 2 (group IIA sPLA 2 ) activity in vitro. In rat mesangial cells, inhibition of group IIA sPLA 2 activity by CGP-43182 results in a 70% reduction of cytokine-stimulated prostaglandin E 2 biosynthesis, suggesting that group IIA sPLA 2 participates in arachidonic acid release and eicosanoid formation. Under these conditions the cytosolic phospholipase A 2 is not aected. 2 In mesangial cells, in addition to inhibition of catalytic activity, the membrane-permeant CGP-43182 completely blocked interleukin 1b (IL1b)-stimulated group IIA sPLA 2 gene expression. 3 A further action of CGP-43182 was a complete inhibition of cyclo-oxygenase-2 gene expression, resulting in a drastic reduction of prostaglandin formation in mesangial cells. 4 Moreover, CGP-43182 completely blocked IL1b-induced gene expression of the inducible nitric oxide synthase, leading to an inhibition of cytokine-stimulated nitric oxide formation. 5 In contrast, the stimulatory eect of the cell-permeant cyclic AMP-analogue, dibutyryl-cAMP, on the induction of these enzymes was not inhibited by CGP-43182. These data indicate that CGP-43182 interferes with IL1b-but not cyclic AMP-activated transcriptional regulation. 6 By studying components of the upstream transcription machinery, we observed an inhibition of NFkB activation by CGP-43182 in IL1b-treated cells. Moreover, we observed that CGP-43182 prevented the phosphorylation and proteolytic degradation of the endogenous NFkB inhibitor, IkB, a process necessary for NFkB activation. 7 From our data, we propose that CGP-43182 is a potent anti-in¯ammatory drug useful for preventing the consequences of a concerted action of cytokine-stimulated pro-in¯ammatory genes mediated by NFkB.

Objective: The role of non-invasive tests for the detection of renovascular hypertension is still a matter of controversy. The 'captopril test' is widely used; its clinical usefulness, however, remains questionable. The aim of the current study was therefore to report our own experience and to review the published data on the diagnostic significance of the test. Patients and methods: Data from 485 hypertensive patients who underwent a captopril test in consecutive order at our institution were analysed retrospectively. After a 30-min resting period in the supine position 50 mg of captopril was given orally. Blood was collected before and 90 min after dosage for the determination of plasma renin concentration (normal range 3.5-8.0 ng/ml/h). An increase by 100% or more of the baseline value was considered a positive response. Blood pressure was recorded at baseline and at 90 min.