Biochemical characterization of peptide alpha-amidation enzyme activities of human neuroendocrine lung cancer cell lines

Peptide alpha-amidation is a posttranslational modification of approximately half of all endocrine and neuroendocrine peptide hormones, including several hormones with mitogenic effects for tumor cells, and is typically essential for complete hormonal bioactivity. alpha-Amidated peptide hormones have been reported to be autocrine growth factors for small cell lung cancer cells. We report here that a variety of human lung tumor cell lines express both enzymes required for the two-step conversion of inactive glycine-extended peptides into their active COOH-terminal alpha-amide analogues. Human tumor cell peptidylglycine alpha-amidation enzymes are present in multiple molecular forms. Both proteins are metalloenzymes which are present at highest concentrations in secretory granules in neuroendocrine cell lines. The expression of these enzymes is positively correlated with expression of other markers of the neuroendocrine phenotype, such as DOPA decarboxylase. Peptidylglycine alpha-amidating enzyme-specific activities are approximately 50-fold higher in extracts of endocrine cell lines (lung small cell and carcinoid) than of nonendocrine lines. Biochemical characterization of the peptidylglycine alpha-amidating enzymes will enable development of tools for detection of endocrine processes in the early stages of neoplasia and for interruption of autocrine stimulation pathways in tumor cells.

Chromosomal assignment of human and rat hypertension candidate genes: type 1 angiotensin II receptor genes and the SA gene

OBJECTIVE

The chromosomal location of candidate genes for a disease, especially if the disease is multifactorial, is an important datum. The objective of the present study was to determine the chromosomal location of candidate hypertensinogenic genes, both in humans and in the rat, a species widely used for animal models of human hypertension. The type 1 angiotensin II receptor (AT1) genes are obvious hypertension candidate genes, whereas the SA gene has recently been shown to cosegregate with hypertension in the rat.

DESIGN

The chromosomal location of the relevant genes was determined using somatic cell hybrids segregating either human chromosomes or rat chromosomes. The presence of the human or rat genes was determined by the Southern blot method, using rat probes.

RESULTS

A single AT1 gene (AT1) was detected in the human genome, and was assigned to chromosome 3, whereas two non-syntenic genes were detected in the rat genome, corresponding to the previously identified A and B subtypes. They were assigned to the rat chromosome 17 (At1a) and 2 (AT1b). The Sa gene was assigned to human chromosome 16 and rat chromosome 1, disclosing a new synteny group retained on rat chromosome 1 and human chromosome 16.

CONCLUSIONS

These chromosomal assignments should be useful for linkage analyses of genes controlling blood pressure. The genes that we studied, and the chromosomes that we identified, deserve special attention in such linkage analyses.

Scientific basis for cancer prevention. Intermediate cancer markers

Promising cancer clinical trials results involving the disruption of early stages of cancer with intervention agents such as tamoxifen or retinoids have led to significant new research interest in developing preventative strategy for the control of epithelial cancers. Key to the efficient progress in this field is a clear understanding of the complex biology of the early stages of cancerization that proceed on the epithelial surface. Systematic analysis of the biology of strategic targets such as growth factors is one approach to this problem. Gastrin-releasing peptide is an autocrine growth factor for certain types of lung cancer cells. Mechanisms involved in the production and activation of this peptide are discussed as an example of how rational approaches to neutralization of cancer promotion biology can be achieved. The tools to monitor the success of this type of intervention also emerge from the understanding of the biology of growth factors, and intermediate end point markers that determine the presence or effects of a growth factor are attractive candidates for evaluation. Additional biologic tools reflecting the early stages of the cancer process need to be validated for use in serially evaluating the status of the relevant epithelium so that the ongoing success of a cancer intervention procedure can be established. Through this type of translational research, important applications of molecular biology may greatly improve the success of preventative strategies for cancer control.

[Criteria for clinical evaluation of antibiotics in pediatrics. The purpose and process for establishing the criteria]

This paper describes the purpose and process for establishing "Criteria for Clinical Evaluation of Antibiotics in the Pediatric Field", which was reported in the Japanese Journal of Antibiotics Vol. 46, May, 1993. The Criteria Committee was organized in November 1991. Four meetings were held to establish the draft criteria. The criteria were applied to the evaluation of oral cephem S-1108 and parenteral cephem SCE-2787. When the criteria were compared with the conventional criteria, the results indicated that no difference was obtained in the efficacy rate as a whole, the sum of "Good" and "Excellent" cases, but there was a difference in the cases judged to be "Excellent". Partial alteration was made to the draft criteria and the Committee produced the final version of the criteria. However, the criteria are far from complete, so it will be subjected to further revision it accordance with future advance in chemotherapy.

An immunohistochemical study of neurofilament and microtubule-associated Tau protein in the enteric innervation in Hirschsprung's disease

The distribution and localization of neurofilament (NF) and microtubule-associated tau protein (Tau) in the colon from Hirschsprung's disease were examined by immunohistochemistry. Specimens of the normoganglionic, oligoganglionic, and aganglionic segments of colons from nine patients with Hirschsprung's disease were used in this study. Normal colon specimens obtained at the time of colostomy closure from two patients with anorectal malformations were also examined as controls. In normoganglionic segments, anti-NF-H and anti-NF-M immunoreactivity appeared within the nerve fibers of both the myenteric and submucosal plexuses. These findings were also observed in the oligoganglionic segments. In the aganglionic segment, hypertrophic nerve fascicules and the nerve fibers in circular muscle were positively stained with anti-NF-H and anti-NF-M antibodies. Anti-Tau staining appeared in the ganglion cell bodies of both myenteric and submucosal plexuses and in nerve fibers distributed among the circular muscles of the normal control colons, and the normoganglionic and oligoganglionic Hirschsprung's specimens. Nerve fibers in the circular muscle layer of aganglionic segments were also stained with anti-Tau serum, although the hypertrophic nerve fascicules in the intermuscular and submucosal layers did not stain. The so-called nerve fascicules distributed in the subserosal layer also did not stain with anti-Tau. These results suggest that Tau may be used as a specific marker to identify ganglion cells and intrinsic nerve fibers in colons affected by Hirschsprung's disease.

Lymphatic drainage of adrenal neuroblastoma

The lymphatic drainage of adrenal neuroblastoma (NB) was investigated in 11 patients using intraoperative vital staining with carbon particle suspension. Carbon staining was most frequent in the nodes at the origin of the renal artery and next most frequent in the interaorticovenous nodes. The staining was characteristically noted in the paraaortic nodes and the nodes around the hemiazygos vein in cases of left adrenal NB, and in the paracaval nodes and the nodes around the azygos vein in cases of right adrenal NB. Histological evaluation confirmed a correlation with lymph node metastases and carbon staining. These findings suggest that the primary regional nodes of adrenal NB are the nodes at the origin of the renal artery, those around the hemiazygos vein in left adrenal NB, and those around the azygos vein in right adrenal NB. The secondary regional nodes are the interaorticovenous nodes, the paraaortic nodes in left adrenal NB, and the paracaval nodes in right adrenal NB. The topography of lymphatic drainage of adrenal NB should be considered in the management of this tumor.

Biofeedback therapy for fecal incontinence after surgery for anorectal malformations: preliminary results

Eight patients with fecal incontinence after surgery for anorectal malformations received one to four sessions of biofeedback therapy. The physiologic status of the anorectum before and after biofeedback therapy was investigated by anorectal manometry and electromyography of the external sphincter. The effectiveness of biofeedback treatment and the indications for its use in patients with fecal incontinence were investigated. Three of the four patients responded well to biofeedback therapy following three or four training sessions. However, in the other five patients who had only one or two sessions, a good response to the therapy was not obtained. Anorectal manometry and electromyography recordings of the external sphincter showed that biofeedback therapy improved voluntary sphincter function. The three good responders had an adequate and resting pressure both before and after biofeedback therapy and had good electrical activity of the external sphincter after therapy. In the presence of adequate resting and pressure, biofeedback therapy should be attempted for the treatment of fecal incontinence after correction of anorectal malformations before resorting to further surgical intervention. However, biofeedback therapy may not be suitable if the sphincters are markedly hypoplastic, or do not surround the anal canal after an inappropriate pull-through operation.

Regulation of vascular angiotensin release

To investigate the regulatory mechanism of the vascular renin-angiotensin system, we perfused isolated rat hind legs with plasma-free buffer and quantified angiotensin peptides in the perfusate. Angiotensin release from hind legs was increased in rats pretreated with losartan (DuP 753) and rats fed a low sodium diet with subsequent furosemide and was decreased in nephrectomized rats and rats given dexamethasone, ethynylestradiol, and triiodothyronine. Using these models, we have attempted to identify which step or component of angiotensin metabolism determines angiotensin release level. Changes caused by these manipulations in plasma renin concentration and basal angiotensin release from hind legs were almost parallel, whereas plasma angiotensinogen concentration and the angiotensin release changed in opposite directions. Infusion of renin in hind legs caused a marked increase in angiotensin release and continued even 1 hour after cessation of renin infusion. Infusion of angiotensinogen did not alter the angiotensin release. Angiotensin clearance and angiotensin I conversion were not affected by either nephrectomy or losartan pretreatment. Aortic renin messenger RNA level was extremely low and not increased by nephrectomy or losartan pretreatment, although kidney renin messenger RNA level was increased by losartan pretreatment. These results provide evidence that plasma renin of kidney origin is the major source of vascular functional renin and plays the determining role in the regulation of vascular angiotensin release. Plasma-derived or locally produced angiotensinogen, locally produced renin, converting enzyme, and angiotensin clearance are not considered to be the primary determinant in the regulation of vascular angiotensin release in these acute and subacute experimental models.

Cellular localization of angiotensin type 1 receptor and angiotensinogen mRNAs in the subfornical organ of the rat brain

The cellular localization of angiotensin type 1 receptor (AT 1) and angiotensinogen mRNA expression in the subfornical organ (SFO) of the rat brain has been studied by means of non-radioactive in situ hybridization combined with immunocytochemistry for glial fibrillary acidic protein (GFAP) and Neutral red staining. The AT 1 receptor mRNA expression is shown to be within putative nerve cells without any association with the glial fibrillary acidic protein (GFAP)-immunoreactive (IR) cells. In contrast the angiotensinogen cRNA expression is associated predominantly with GFAP-IR cells. The results demonstrate that a neuronal AT 1 receptor mediates the actions of circulating angiotensin II on the SFO and that the angiotensinogen mRNA is predominantly expressed in the SFO astroglial cells.

Angiotensin II receptors: cloning and regulation

Angiotensin II subtype 1 (AT1) receptor cDNA was cloned by expression cloning from bovine adrenal cortical cells. Human AT1 receptor was also cloned. These receptors were found to have a seven transmembrane structure. The receptor seems to interact with more than one type of G-proteins. AT1 consists of subtypes. cDNA for AT1A was cloned from rat kidney and that for AT1B was cloned from rat adrenal by plaque hybridization. They have similar base sequences in the coding region but are different in non-coding regions. Their functional implication is not clear. The regulation of the receptors occur at many stages. Expression of mRNA is studied in cultured rat mesangial cells. It was down regulated by angiotensin II and cAMP. On the other hand in whole body experiments, chronic infusion of angiotensin II was shown to upregulate adrenal AT1, and bilateral nephrectomy or losartan (CAS 124750-99-8) administration reduced AT1 mRNA expression. In addition to AT1 and AT2 the presence of a new subtype AT3 has been shown.

Biliary tract complications in patients with hypoganglionosis and chronic idiopathic intestinal pseudoobstruction syndrome

The biliary tract system was studied in two patients with hypoganglionosis and chronic idiopathic intestinal pseudoobstruction syndrome (CIIPS) to evaluate manifestations of these diseases, especially as for underlying motility disorder. In a 3-year-old boy with hypoganglionosis, cholelithiasis was diagnosed and the gallbladder specimen showed a markedly hypoplastic neural plexus on histopathology as was found in his total alimentary tract. In a 2-year-old girl with CIIPS, echo-guided gallbladder wall motility testing demonstrated an impaired response to a ceruletide diethylamine stimulation. These clinical experiences in two patients suggest that these pathological entities may be frequently associated with biliary tract complications not only due to a consequence of total parenteral nutrition, but also due to a possible intrinsic involvement of biliary tract dysmotility.

Identification of a candidate gene responsible for the high blood pressure of spontaneously hypertensive rats

OBJECTIVE

We have recently isolated a gene, designated as the SA gene, which is more than 10 times more abundantly expressed in the kidneys of spontaneously hypertensive rats (SHR) than in those of Wistar-Kyoto (WKY) rats. To address the issue whether the SA gene is one of the genes responsible for the hypertension of SHR, a genetic cosegregation analysis of the blood pressure values with the genotypes in an F2 rat population was undertaken in this study.

METHODS AND DESIGN

Male F2 rats were bred from SHR and WKY rats. The genotypes of the SA gene of the F2 rats were determined by utilizing the StuI restriction fragment length polymorphism of the SA gene between SHR and WKY rats. The blood pressure values were determined by the tail-cuff method. The effect of the genotype of the SA gene on the blood pressure of the F2 rats was analysed by one-way analysis of variance.

RESULTS AND CONCLUSION

The blood pressure of the F2 rats inheriting two SHR alleles of the SA gene was significantly higher than that of the F2 rats inheriting two WKY alleles. This indicates that the SA gene, or a gene closely linked to it, has a capacity to influence the blood pressure values of the F2 rat population. Further studies to identify functions of the SA gene products will be necessary.

Molecular genetics of the SA-gene: cosegregation with hypertension and mapping to rat chromosome 1

OBJECTIVES

The SA-gene shows markedly higher levels of expression in the kidneys of spontaneously hypertensive rats (SHR) than in their non-hypertensive reference strain, the Wistar-Kyoto (WKY) rat. Based on the important role of the kidney in blood pressure regulation, the possibility has been raised that this gene, the translational product of which remains unknown, may participate in the pathogenesis of primary hypertension. The present study was conducted to test this hypothesis and to ascertain the chromosomal localization of the SA-gene.

DESIGN

A cosegregation study was performed using an F2 intercross between stroke-prone SHR (SHRSP) and WKY rats, and a previously described restriction fragment length polymorphism of the SA-gene for characterization of genotype. Mapping of the SA-gene was accomplished by screening a somatic cell-hybrid panel and by linkage group analysis.

RESULTS

A statistically significant difference in systolic blood pressure was found after sodium loading, but not under basal conditions between groups of rats defined by zygosity at the SA locus, consistent with a hypertensive effect of the SHRSP allele. No effect of SA genotype on diastolic blood pressure was observed. The SA-gene was localized on rat chromosome 1.

CONCLUSIONS

This study establishes the SA locus on chromosome 1 as a region in which a gene or genes contributing to blood pressure regulation in this model are localized, and provides further evidence for a possible role of the SA-gene in the pathogenesis of hypertension.

[Pharmacokinetic study on oral antibiotics in pediatrics. III. A pharmacokinetic study on cefprozil in pediatrics]

The absorption and excretion were studied in the field of pediatrics, and pharmacokinetic analyses were performed. 1. Influence of food: Cefprozil (CFPZ, BMY-28100) was given to 6 school children in a before and after meal cross over design. With before meal administration, Tmax was 1.11 +/- 0.08 hours, Cmax was 5.08 +/- 0.27 micrograms/ml, T 1/2 was 0.77 +/- 0.09 hour, and urinary recovery rate (0-8 hours) was 55.2 +/- 4.7%. With after meal administration, these values were 1.31 +/- 0.04 hours, 3.98 +/- 0.38 micrograms/ml, 0.72 +/- 0.03 hour and 46.3 +/- 9.0%, respectively. A shorter Tmax value was, obtained higher Cmax and more or less higher urinary recovery rate when the drug was administered before meal, hence the food was considered to influence the absorption of the drug. 2. Dose effect: CFPZ was given on empty stomach to 6 school children in doses of 7.5 mg/kg and 15.0 mg/kg in the cross over design. With the lower dose Cmax was 6.19 +/- 0.36 micrograms/ml and AUC was 14.90 +/- 1.02 micrograms.hr/ml, and with the higher dose they were 12.38 +/- 1.29 micrograms/ml and 28.56 +/- 1.79 micrograms.hr/ml. Dose effects appeared to exist for CFPZ. A higher urinary recovery rate was obtained at the dosage of 7.5 mg/kg (82.1 +/- 6.4%) compared to the dosage of 15.0 mg/kg (51.1 +/- 7.1%). 3. Influence of age: CFPZ was given on empty stomach to 17 school children, 19 younger children and 5 infants. Tmax were 1.07 +/- 0.09, 1.06 +/- 0.07, and 1.40 +/- 0.09 hours, respectively for the 3 groups, hence significantly longer Tmax was observed in infants. Cmax were higher in older children and they were 5.62 +/- 0.38, 4.72 +/- 0.53 and 4.05 +/- 0.33 micrograms/ml, in the 3 age groups, respectively. T 1/2 were 0.73 +/- 0.04, 0.78 +/- 0.09 and 0.98 +/- 0.12 hour, respectively, it was longer in infants. The AUCs were not different among the 3 groups, but different urinary recovery rates were obtained with higher recovery in school children, with values of 64.1 +/- 4.3, 44.3 +/- 3.8 and 51.6 +/- 3.3%, respectively.

[Clinical study on cefprozil in pediatrics]

Clinical efficacy and safety of cefprozil (CFPZ, BMY-28100), a newly developed oral cephalosporin, were studied in our pediatric department. Clinical effectiveness, bacteriological effectiveness and side effects were studied in 116 pediatric patients with ages ranging 4 months to 11 years. CFPZ was given 4.6-14.1 mg/kg daily in 3 times for 3-10 days. Clinical efficacies were evaluated in 112 patients, and the therapeutic effectiveness were excellent in 1 and good in 6 for 7 patients with acute pharyngitis, excellent in 24 and good in 26 for acute purulent tonsillitis, excellent in 3, good in 8 and fair in 1 for acute bronchitis, excellent in 21, good in 7, fair in 1 and poor in 1 for acute pneumonia, excellent in 1 acute purulent parotitis, excellent in 2 and good in 7 for acute UTI, good in 1 impetigo, fair in 1 periproctal abscess and good in 1 acute enteritis. The effectiveness rate was 96.4%. Bacteriologically, 4 strains of Staphylococcus aureus (beta-lactamase producing strains), 1 strain of Staphylococcus epidermidis (beta-lactamase producing strain), 2 strains of Streptococcus pneumoniae, 2 strains of Streptococcus agalactiae, 4 strains of beta-Streptococcus, 1 strain of Klebsiella pneumoniae (beta-lactamase producing strain) and 1 strain of Salmonella C2 were all disappeared, and of 22 strains of Streptococcus pyogenes, 20 strains were disappeared, 1 was decreased and 1 was unknown, of 5 strains of Escherichia coli (3 beta-lactamase producing strains), 4 were disappeared and 1 was decreased, of 29 strains of Haemophilus influenzae (14 beta-lactamase producing strains), 14 were disappeared, 11 were decreased, 3 persisted and 1 was unknown and of 2 strains of Haemophilus parainfluenzae (1 beta-lactamase producing strain), 1 was disappeared and 1 persisted. The bacteriological eradication rates for Gram-positive bacteria and Gram-negative bacteria were 97.1% and 56.8%, respectively, and the drug was especially effective against Gram-positive bacteria. No side effects nor refusal of ingestion were observed. As abnormalities in laboratory test results, 3 cases of elevation of eosinophil counts and 1 of elevation of platelet counts were observed. In conclusion, CFPZ was considered to be a safe and highly effective antibiotic in pediatric infections.

Further evidence of the SA gene as a candidate gene contributing to the hypertension in spontaneously hypertensive rat

We have recently reported that the allele of the SA gene of the Spontaneously hypertensive rat (SHR) has a capacity to influence blood pressure in a F2 rat population prepared from SHR and Wistar-Kyoto rat. In the present study, we have undertaken a similar genetic co-segregation analysis of the F2 rat population prepared from SHR and Lewis rat. The result indicated that, although overall effects of the SA gene genotypes on blood pressure were not significant, a correlation of the genotypes of the SA gene with blood pressure was significantly observed in the female rats of this population. The present results further strengthen our hypothesis that the SA gene, or a gene closely linked to this gene, has a capacity to influence blood pressure.

Differential regulation of rat AT1a and AT1b receptor mRNA

Rat type 1 angiotensin II receptor has two subtypes, namely type 1a and type 1b. The regulation of the expressions of these two subtype receptor mRNAs was studied by using a competitive polymerase chain reaction method. The expression of the type 1a mRNA in the liver was negatively and that of the type 1b mRNA in the adrenal was positively modulated by bilateral nephrectomy. In the ventricle of 16 week old Spontaneously hypertensive rat, the expression level of the AT1b receptor mRNA was higher than that in the ventricle of the age-matched Wistar-Kyoto rat, while the expression levels of the AT1a mRNA in the ventricle were almost similar between the two strains at this age. Although type 1a and type 1b have almost similar functional properties, the expressions of their mRNAs were differentially regulated.

Motility and sensation of the rectosigmoid and the rectum in patients with anorectal malformations

Motility of the rectosigmoid and rectum and reservoir function of the rectum after surgery for anorectal malformations were investigated in 32 patients (17 with high type, 6 with intermediate type, and 9 with low type anomaly) aged 5 to 16 years. All 32 patients were examined manometrically as well as with a newly devised myoelectrical method. Manometry showed that the values of maximum anal pressure and anorectal pressure difference in the high type were significantly lower than those in the low type. However, the incidence of contractile activity of the rectosigmoid was not significantly different between these two groups. The threshold sensation pressure and the maximum tolerable pressure in the high type were significantly higher than those in the low type, and the rectal compliance in the high type was significantly lower than that in the low type. Electromyography was recorded at 8 cm and 5 cm from the anal verge. Two types of slow waves were observed, a faster rhythm and a slower rhythm. Their frequency was similar in the three groups. However, the numbers of spike bursts in the high type and intermediate type were significantly higher than those in the low type. These results indicate that in addition to an inadequate anal resting pressure a loss of optimal rectal sensation or rectal reservoir function might be associated with fecal incontinence in the high type and that increased spike bursts might play some role in rectal motility.

[Laboratory and clinical evaluation of meropenem in pediatric field]

We performed laboratory and clinical evaluation of meropenem (SM-7338, MEPM), a new carbapenem antibiotics, in pediatric field. Pharmacokinetics of MEPM was examined with 5 patients, at a dose of 10 mg/kg via 30 minutes drip infusion. Mean plasma concentrations at 30 minutes, 1, 1.5, 2.5, 3.5 and 5.5 hours after dose were 18.8, 6.97, 3.62, 1.14, 0.43 and 0.12 micrograms/ml, respectively, with a half life of 0.96 hour. The urine recovery rate in 6 hours was 70.4%. Clinical efficacy of MEPM was evaluated in 36 patients with various infectious diseases. MEPM was administered at doses ranging 9.5 to 30.6 mg/kg/dosage, 3 to 4 times a day, 21/3 to 10 days. Clinical effects were excellent in 24, good in 11, fair in 1, with an efficacy rate of 97.2%. Bacteriologically, all causative organisms except one each of Haemophilus influenzae and Salmonella enteritidis were eradicated, an eradication rate for Gram-positive and Gram-negative bacteria were 100% and 93.3%, respectively. No side effects were observed. Elevations of GOT and/or GPT were noted in 2 patients. From the above results, we believe that MEPM is a highly effective and safe drug for patients with various infectious diseases in pediatric fields.

Thermography in a child with varicocele

A 12-year-old boy with a left-sided varicocele (Grade 3) was assessed preoperatively and followed postoperatively by computer-assisted infrared thermography. The temperature of the left scrotum was 35.4 degrees C before surgery which was 4 degrees C higher than that of the right scrotum. After ligation of the left internal spermatic vein and removal of the varicocele, scrotal thermograms 39 days and 12 months after operation were normal. Therefore, it seems that thermography is very valuable in the evaluation of testicular function in children with varicocele, in whom semen analysis is impossible.

The distribution of angiotensin II AT1 receptor subtype mRNA in the rat brain

The present study demonstrates the existence and regional distribution of angiotensin II AT1 receptor subtype mRNA expression in the rat brain by the use of in situ hybridization and RNase protection assay. Substantial expression levels in the brain have only been detected in certain distinct areas, such as the subfornical organ, the parvocellular part of the paraventricular hypothalamic nucleus, and the median preoptic nucleus. The results give further evidence for the involvement of the angiotensin II AT1 receptor subtype in the classical functions of central angiotensin II, like blood pressure control, body fluid homeostasis and in corticotropin-releasing factor (CRF) secretion.

Quantitative analysis of renin gene expression in extrarenal tissues by polymerase chain reaction method

OBJECTIVE

To evaluate the significance of locally synthesized renin in the pathogenesis of hypertension, we investigated modulation of the renin gene expression in extrarenal tissues.

DESIGN

Expression levels of renin messenger (m)RNA in various tissues were determined in the genetically hypertensive rats and their control strains. Effects of salt, captopril and clonidine upon renin gene expression were also investigated.

METHODS

Due to the very low expression level of renin mRNA in extrarenal tissues, a competitive polymerase chain reaction method of assessment was applied. Total RNA from various tissues combined with a synthetic deletion-mutated renin RNA were reverse-transcribed and the resultant complementary DNA mixtures were amplified in one reaction in which the same primers were used.

RESULTS

Expression levels of the renin mRNA in various parts of the central nervous system of 4-week-old spontaneously hypertensive rats were approximately twofold higher than those of age-matched Wistar-Kyoto rats and expression levels in the brain were positively modulated by the administration of either captopril or clonidine.

CONCLUSIONS

The importance of the brain renin angiotensin system in the pathogenesis of hypertension in spontaneously hypertensive rats was strongly suggested.