Methods for detection of MDR1 mRNA expression on acute myelogenous leukemia cells

Overexpression of the human multidrug resistance gene (MDR1) on acute myelogenous leukemia (AML) correlates with poor prognosis. We evaluated several methods for mRNA estimation to standardize simple and reliable techniques for identifying MDR1 positive leukemia among untreated AMLs in large scale studies. Northern blot detection of MDR1 mRNA suffered from low signal-to-noise ratio under the conventional conditions, that was improved mainly by removing unincorporated radioactivity. The amount of MDR1 transcripts on positive cells was estimated less than 10% of that of constitutive mRNA species. A modified method seemed useful in estimating the total amount of the MDR1 mRNA in a whole leukemic cell population, and suitable to study stock samples or for large prospective clinical trials. RT-PCR was more sensitive in detecting MDR1 mRNA than Northern blot analysis, and the very feature made it virtually impossible to exclude contamination with normal hematopoietic cells. This procedure showed that FAB M3 leukemias were essentially MDR1 negative, and there existed frequently myelodysplastic syndrome subpopulation which had excessive MDR1 transcripts. In situ hybridization of the mRNA with a FITC-labeled phosphorothioate oligonucleotide probe was visualized using flowcytometry or con-focus lightmicroscopy, enabled us to recognize the difference between multidrug resistant K562/ADM and its wild type.

Impaired coronary flow reserve immediately after coronary angioplasty in patients with acute myocardial infarction

OBJECTIVE

To examine coronary flow reserve immediately after emergency coronary angioplasty in patients with acute myocardial infarction.

DESIGN

A 3 F coronary Doppler catheter was used to measure coronary blood flow velocity in the infarct artery and in the non-infarct artery. Maximal hyperaemia was produced by 10 mg of intracoronary papaverine and coronary flow reserve was calculated.

PATIENTS

11 patients with acute myocardial infarction undergoing both emergency coronary angioplasty (4.7 (3.6) h after the onset of chest pain (mean (SD))) and at follow up catheterisation 16 (4) days after angioplasty.

SETTING

Hiroshima City Hospital.

RESULTS

There was no stenosis of > or = 50% in the coronary artery of interest. Immediately after coronary angioplasty the mean (1 SD) coronary flow reserve of the infarct artery was significantly less than that of the non-infarct artery (1.4 (0.4) v 2.8 (0.8), p < 0.001). At follow up catheterisation the coronary flow reserve of the infarct artery increased almost to the value of the non-infarct artery (2.8 (1.2) v 3.1 (0.8) p = NS).

CONCLUSION

The coronary flow reserve in the infarct region was severely impaired immediately after reperfusion, even with a widely patent infarct artery. This could restrict the beneficial effects of reperfusion therapy, especially when there is a severe residual stenosis.

Quantitation of human immunodeficiency virus type 1 infection kinetics

Tissue culture infections of CD4-positive human T cells by human immunodeficiency virus type 1 (HIV-1) proceed in three stages: (i) a period following the initiation of an infection during which no detectable virus is produced; (ii) a phase in which a sharp increase followed by a peak of released progeny virions can be measured; and (iii) a final period when virus production declines. In this study, we have derived equations describing the kinetics of HIV-1 accumulation in cell culture supernatants during multiple rounds of infection. Our analyses indicated that the critical parameter affecting the kinetics of HIV-1 infection is the infection rate constant k = Inn/ti, where n is the number of infectious virions produced by one cell (about 10(2)) and ti is the time required for one complete cycle of virus infection (typically 3 to 4 days). Of particular note was our finding that the infectivity of HIV-1 during cell-to-cell transmission is 10(2) to 10(3) times greater than the infectivity of cell-free virus stocks, the inocula commonly used to initiate tissue culture infections. We also demonstrated that the slow infection kinetics of an HIV-1 tat mutant is not due to a longer replication time but reflects the small number of infectious particles produced per cycle.

[S-phase fraction and malignant potential in DNA diploid colorectal cancer]

Patients with DNA diploid tumor have a significantly longer survival than those with DNA aneuploid in colorectal cancer, but some patients with diploid tumor show poor survival. For assessing malignant potential in diploid colorectal cancer, flow cytometric analysis of S-phase fraction (SPF) was investigated using paraffin-embedded materials from 79 carcinoma patients who had been treated from 1971 to 1989. There was no significant correlation between SPF and clinicopathological factors (such as sex, tumor size, tumor location, macroscopical type, depth of invasion, node metastasis, peritoneal dissemination, liver metastasis and clinical stage). Mean SPF was significantly higher in poorly differentiated type carcinomas than in well differentiated type carcinomas. Patients with higher SPF had a tendency to poorer survival than those with lower SPF. From these results, it was concluded that SPF represents histological differentiation and that SPF may be a prognostic indicator, in diploid colorectal cancer.

Tissue inhibitor of metalloproteinase 1 is a negative regulator of the metastatic ability of a human gastric cancer cell line, KKLS, in the chick embryo

Tissue inhibitors of metalloproteinases (TIMPs) are the negative regulators of matrix metalloproteinases that degrade extracellular matrix. We examined the regulatory role of TIMP-1 in the metastatic activity of human gastric cancer cell lines in chick embryos because unregulated matrix metalloproteinase activities are believed to be essential during metastatic processes. One of the nine cell lines examined, KKLS cells, formed metastatic colonies in the chick livers. These cells expressed undetectable levels of TIMP-1, and this was not inducible by 12-O-tetradecanoylphorbol 13-acetate. Derivatives of KKLS cells with different levels of TIMP-1 expression were prepared by transfection of the human TIMP-1 complementary DNA controlled by a simian virus 40 early promoter. Metastatic abilities were suppressed by almost 70% in the transfectants expressing high levels of TIMP-1. In contrast, no suppression was observed in the control transfectants or in cells expressing the transfected TIMP-1 gene at low levels. These data indicate that a reduced expression of TIMP-1 in KKLS cells is responsible for their consequent metastatic potential. Moreover, it suggests that matrix metalloproteinase enzymatic activities are a prerequisite for metastatic activity in this experimental model system.

[Possibility of lymphatic absorption of epidermal growth factor from intestine]

Epidermal growth factor (EGF) in the milk fat globule membrane (MFGM) emulsion enhanced the absorption of this factor from the intestine, especially to the intestinal lymph. Most of the radioactive EGF administered was degraded to small molecular weight materials. These degraded materials were absorbed and appeared in both the intestinal lymph and portal vein blood. However, a certain portion of EGF, although small, appeared in the lymph maintaining the original molecular mass. The MFGM emulsion used enhanced the lymphatic absorption of intact EGF, suggesting that this dosage form increased the absorption of EGF, protected the degradation of EGF in the intestine or promoted the absorption of intact EGF. The enhancing effect on the absorbed dose percentage of EGF recovered using MFGM emulsion was also observed in the portal vein plasma. However, the effect on the absorption of intact EGF was much larger in the lymph than in the portal vein.

[Evaluation of the right ventricular function in postoperative esophageal cancer patients]

We evaluated the right ventricular function in pre- and post-operative esophageal cancer patients who had no complications after surgery by measurement of cardiopulmonary hemodynamics, right ventricular ejection fraction (RVEF) and right ventricular end-diastolic volume index (RVEDVI) using Swan-Ganz catheter and the thermodilution technique. The measurement of RVEF, RVEDVI and other cardiopulmonary hemodynamics were performed from the preoperative day to the 3rd postoperative day. The values of RVEF were stable about 40% from preoperative day to 3rd. RVEDVI was varied at 93.6 +/- 26.3 ml/m2 (preoperative day), 83.6 +/- 15.0 ml/m2 (after surgery), 70.2 +/- 10.6 mg/m2 (morning of the 1st POD), 95.6 +/- 19.4 ml/m2 (evening of the 1st POD), 103.2 +/- 17.9 m/lm2 (morning of the 2nd POD), 1108.3 +/- 14.2 ml/m2 (evening of the 2nd POD) and 112.4 +/- 31.0 ml/m2 (morning of the 3rd POD). The values of RVEDVI on the morning of the 1st POD were statistically lower than those at other times (p < 0.05). The values of RVEDVI were not correlated with mean pulmonary arterial pressure and pulmonary arteriolar resistance which were the afterload of the right ventricle. These data suggest that the right ventricular function of the patients who underwent esophagectomy with no complication does not change and that the changes of RVEDVI are influenced by the preload of the right ventricle.

Torsion of the human semicircular canals and its influence on their angular relationships

We used a computer-aided three-dimensional reconstruction and measurement method to measure torsion of the the semicircular canals (SCCs) in 10 normal human temporal bones from 10 individuals (3 months to 76 years old). Torsion of each SCC was measured as the angle between the "standard line" (the line connecting the ampullated and nonampullated ends of the SCC) and the plane of greatest SCC torsion. Torsion was greatest for the anterior SCC (16.4 +/- 3.6 degrees), followed by the lateral SCC (9.5 +/- 6.7 degrees) and the posterior SCC (8.5 +/- 4.2 degrees). The angles between the overall plane described by each SCC and the other SCCs between the anterior and lateral, the anterior and posterior, and the posterior and lateral SCCs were also measured and were found to be 78.7 +/- 10.0, 107.9 +/- 5.5, and 87.3 +/- 6.9 degrees, respectively. Finally the angles between the torsion plane of each SCC and the others were measured and found to be 92.6 +/- 15.4, 95.8 +/- 11.2, and 90.9 +/- 8.3 degrees, respectively. These results indicate that on average torsion in the SCCs tend to bring the angle between pairs of SCCs close to a right angle. This tendency to have a right angle between SCCs is thought to promote optimal vestibular function. Speculation is offered regarding the etiology of the greater torsion of the anterior SCC.

Escape from redox regulation enhances the transforming activity of Fos

Fos and Jun form dimeric complexes that bind to DNA sequences containing activator protein 1 (AP-1) sites and regulate gene expression. The in vitro DNA-binding activity of these proteins is sensitive to reduction-oxidation (redox). Reduction of a single conserved cysteine residue, located in the DNA-binding domain, either by reducing agents or by a nuclear redox factor (Ref-1), is required for AP-1 DNA-binding activity. Replacing the critical cysteine with serine results in a protein that can bind to DNA in vitro even under oxidizing conditions. To determine whether redox control affects the function of Fos in vivo, we have constructed, and compared the properties of, retroviral vectors expressing either a truncated Fos protein (F118-211) or a truncated Fos protein in which the critical cysteine was replaced by serine (FC154S). In infected chicken embryo fibroblasts (CEFs), both vectors expressed similar levels of Fos protein, which formed heterodimers with Jun at equivalent efficiencies. However, extracts from cells expressing FC154S exhibited a threefold increase in AP-1 DNA-binding activity compared with cells expressing F118-211. Furthermore, this enhanced binding activity was resistant to treatment with the oxidizing agent diamide. Infection of CEFs by virus expressing FC154S resulted in increased numbers of transformed colonies and an increase in colony size compared with those obtained following infection by virus expressing Fos 118-211. These results suggest that redox regulation may limit the total level of functional Fos-Jun complexes in vivo and that escape from this control enhances transforming activity.

The prognostic significance of exercise-induced silent ST-segment depression in patients after myocardial infarction

To evaluate the prognostic value of exercise-induced silent ST-segment depression, 157 patients who had suffered myocardial infarction underwent symptom-limited exercise testing and coronary angiography. Patients were divided into 3 groups according to the presence or absence of ischemic ST-segment depression and angina during exercise testing. Group A patients had ST-segment depression without angina. Group B patients had both ST-segment depression and angina. Group C patients had neither ST-segment depression nor angina. All patients were followed without coronary artery bypass graft or percutaneous transluminal coronary angioplasty for an average of 36 months and the frequency of coronary events (cardiac death, recurrent myocardial infarction and unstable angina pectoris) was compared. Group A patients had less severe coronary artery disease, greater coronary reserve during exercise and exercised longer than group B. However, the prognosis of group A was similar to group B, and was worse than group C. Using the Cox proportional hazards model, ischemic ST-segment depression was the most useful index for predicting future coronary events among the baseline values, coronary angiographic and exercise testing variables. However, angina during exercise testing was not an independent predictor. Thus, post-infarction patients showing exercise-induced ST-segment depression should be treated carefully regardless of the presence or absence of angina.

Superoxide dismutase restores contractile and metabolic dysfunction through augmentation of adenosine release in coronary microembolization

BACKGROUND

This study was undertaken to test the hypothesis that administration of superoxide dismutase (SOD) restores the contractile and metabolic dysfunction in coronary microembolization and that these beneficial effects of SOD are attributable to the restoration of 5'-nucleotidase activity and subsequent augmentation of adenosine release.

METHODS AND RESULTS

In 78 dogs before and after an injection of microspheres (15 microns in diameter) into the left anterior descending coronary artery, regional coronary blood flow (CBF), fractional shortening (FS), and lactate extraction ratio (LER) were measured with and without administration of recombinant human SOD (50 micrograms/kg/min i.c.). In the untreated dogs (n = 6), both FS and LER decreased after coronary microembolization (2.0 x 10(5) microspheres per ml CBF [mL/min]). FS and LER decreased from 24.2 +/- 1.3% to 5.1 +/- 1.2% and from 23.0 +/- 1.1% to -10.5 +/- 2.9%, respectively. These ischemic changes were associated with coronary hyperemic flow (141 +/- 8 versus 92 +/- 1 mL/100 g/min) and adenosine release (5.8 +/- 0.5 versus 0.4 +/- 0.1 nmol/100 g/min). Pretreatment with SOD augmented the hyperemic flow to 164 +/- 4 mL/100 g/min and enhanced the release of adenosine (9.6 +/- 0.6 nmol/100 g/min) associated with improvement of functional and metabolic dysfunction (FS, 14.8 +/- 2.3%; LER, 15.1 +/- 3.1%). Administration of SOD at 10 minutes (n = 5) and 30 minutes (n = 5) after coronary embolization restored the contractile function and lactate metabolism (at 10 minutes: FS, 16.7 +/- 2.2% and LER, 16.7 +/- 3.9%; at 30 minutes: FS, 11.1 +/- 1.3% and LER, 7.2 +/- 3.1%). However, administration of SOD 60 minutes after coronary embolization (n = 6) did not restore the contractile and metabolic dysfunction. The restoration of the contractile and metabolic dysfunction by SOD treatment was blunted by adenosine receptor blockade with 8-phenyltheophylline (n = 5). Myocardial 5'-nucleotidase activity at 2 hours after embolization was restored with SOD treatment at 10 minutes (n = 5) and 30 minutes (n = 5) after embolization. However, SOD treatment at 60 minutes after embolization (n = 6) did not restore 5'-nucleotidase activity compared with the SOD pretreatment group. Furthermore, coronary submaximal vasodilation induced by papaverine (n = 5) and adenosine (n = 5) abolished the beneficial effects of SOD.

CONCLUSIONS

We conclude that 1) in sustained myocardial ischemia, SOD treatment attenuates ischemic injury caused by coronary microembolization by restoration of 5'-nucleotidase activity and augmentation of adenosine release; 2) this beneficial effect of SOD is observed even after coronary microembolization; and 3) the beneficial effects of SOD are attributable to coronary vasodilation produced by augmented adenosine release.

Cells of origin of the spinoparabrachial fibers in the rat: a study with fast blue and WGA-HRP

The internal lateral (IL) subnucleus of the parabrachial nucleus (PB), which is one of the seven lateral subnuclei of the PB, receives information from the spinal cord. The IL subnucleus perhaps relays nociceptive signals to the intralaminar nuclei of the thalamus, apparently being implicated in the motivational-affective component of pain reaction. However, cells of origin of spinal fibers to the IL subnucleus have not been investigated sufficiently. We intended to clarify these cells by injection of fast blue or wheat germ agglutinin-conjugated horseradish peroxidase into the IL subnucleus and/or other lateral subnuclei in the rat. When the tracer was injected into the IL subnucleus, many cells were labeled bilaterally in laminae I, V, and VII, and in the dorsolateral and dorsomedial parts of the lateral funiculus throughout the entire length of the spinal cord. A small number of labeled cells appeared ipsilaterally in laminae II-IV and VI in the upper cervical segments and contralaterally in laminae VIII and X throughout the spinal cord. Labeled cells in lamina I were more numerous ipsilaterally than contralaterally in the first two cervical segments but were more numerous contralaterally than ipsilaterally in the remaining spinal segments. Labeled cells were seen with a contralateral predominance in lamina VII, but with an ipsilateral predominance in lamina V and in the dorsolateral and dorsomedial parts of the lateral funiculus. With tracer injected into the lateral subnuclei of the PB, excluding the IL subnucleus, labeled cells were found primarily in lamina I throughout the entire length of the spinal cord. These results show that cells giving rise to spinoparabrachial fibers were more numerous and more widely distributed than previously reported.

Regulatory mechanism of 92 kDa type IV collagenase gene expression which is associated with invasiveness of tumor cells

92-kDa Type IV collagenase, a member of matrix metalloproteinases, is believed to play a critical role in physiological tissue-remodeling processes and also in many pathological conditions such as tumor invasion. We analyzed the 5'-flanking sequence of the 92 kDa type IV collagenase gene that controls the expression of the gene by ligating it to the chloramphenicol acetyltransferase gene. Deletion and mutation analysis revealed that three motifs, homologous to the binding sites for AP-1, NF-kappa B, and Sp-1 proteins, contributed positively to induction by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and tumor necrosis factor alpha (TNF alpha). The AP-1 site was indispensable but not sufficient for the induction and required synergistic cooperation with either the kappa B or the Sp-1 site. In OST cells, a nuclear factor which bound to Sp-1 was constitutively expressed, and those bound to AP-1 and kappa B elements were rapidly induced by TNF alpha treatment. Comparison of the findings with those for the promoters of other TPA-inducible matrix metalloproteinases, interstitial collagenase and stromelysin 1, revealed that the signal to the AP-1 sites is common for the TPA-inducibility of the genes but that the signals to the kappa B or Sp-1 sites, which are not present in interstitial collagenase and stromelysin 1 promoters, are the unique determinant for the inducibility of the 92 kDa type IV collagenase gene.

Double t(1;7)(p36;p11) in a megakaryocytic crisis of chronic myelogenous leukemia with variant t(5;9;22)

A 56-year-old man with chronic myelogenous leukemia (CML) who presented with a variant Ph chromosome, t(5;9;22)(q13;q34;q11), developed a unique additional chromosomal change of a double reciprocal t(1;7)(p36;p11) during the accelerated phase. A minor clone that had two copies of 1p+ and a copy of 7p- with a normal chromosome 7 was observed simultaneously. The patient underwent a megakaryocytic crisis. Surface marker of the blasts was positive for CD13, CD33, HLA-DR, CD41a, and CD42b, and negative for CD14 and lymphoid markers. Sequential chromosome analysis suggests that the double t(1;7) was caused by a multistep event consisting of duplication of both derivative chromosomes accompanied by loss of normal chromosomes 1 and 7. This may be the first report of a double reciprocal chromosomal translocation in a hematopoietic neoplasm.

Localization of apolipoprotein(a) and B-100 in various renal diseases

Recently it has become clear that abnormalities of lipid metabolism play a large role in the progression of renal diseases. To investigate the relationship between lipids and kidney tissue, we employed an immunofluorescent technique to determine the localization pattern of apolipoprotein(a) [apo(a)], apoB-100, and low-density lipoprotein receptor in the glomeruli, and analyzed the relationship between their presence and the clinical and histological findings of a total 92 patients with glomerular diseases. Immunostaining showed co-localization of apo(a) and apoB-100 in glomeruli. The patients were divided into three groups, as follows: both apo(a) and apoB-100 positive (Group 1; 38 cases), apo(a) positive only (Group 2; 19 cases) and apo(a) negative (Group 3; 35 cases). Group 1 had more severe proteinuria, higher levels of lipoprotein(a) [Lp(a)], and lower total protein levels than Group 3. Group 1 had a higher prevalence of glomerulosclerosis and interstitial changes than Group 3. Group 2 had more severe proteinuria and a higher prevalence of glomerulosclerosis than Group 3. Although apo(a) and apoB-100 are almost absent in normal controls, these apoproteins [and presumably lipoproteins Lp(a)] are present in the glomeruli of patients with glomerular diseases. The data support the view that these apoproteins play a significant role in progressive renal diseases.

[Genetic defect of the hyperbilirubinemic Gunn rat, a model for Crigler-Najjar syndrome type I]

The hyperbilirubinemic Gunn rat lacks hepatic UDP-glucuronosyltransferase (UDPGT) activity toward bilirubin and has been used as an animal model for human Crigler-Najjar syndrome type I. Rat liver bilirubin UDPGT cDNA was isolated. The cDNA shared an identical 913-bp sequence (corresponding to the C-terminal 247 amino acid residues) with that for phenol UDPGT whose activity was also deficient in the Gunn rat. The bilirubin UDPGT gene was mapped at the position of 37 on mouse chromosome 1 by analyzing restriction endonuclease fragment length variations using the rat bilirubin UDPGT cDNA as a probe. The genetic defect of bilirubin UDPGT in the mutant rat was proved to be a -1 frameshift mutation. The mutation was found not only to be located in the region where the cDNA for bilirubin UDPGT shared the identical sequence with that for phenol UDPGT but also to occur in the same position in the two cDNAs from the mutant.

Renal histology in two adult patients with type I glycogen storage disease

Two adult patients with type I glycogen storage disease (I-GSD) had chronic renal disease with heavy proteinuria. Renal biopsies showed focal glomerular sclerosis, interstitial fibrosis, tubular atrophy or vacuolation, and prominent arteriosclerosis. Marked glomerular hypertrophy was demonstrated histometrically. Oil red O staining in one patient revealed numerous lipid deposits in the glomerular mesangium, tubular epithelial cells and interstitium. Electron microscopy in the other patient revealed diffuse thickening of the glomerular basement membrane (GBM) and lipid droplets within the mesangium. The glomerular hypertrophy, thickening of the GBM, and subsequent sclerosis were similar to those in insulin-dependent diabetes mellitus. These findings may explain the similarities between the natural histories of renal involvement in the two disorders. Particularly, glomerular hypertrophy may be a key step leading to glomerular sclerosis, which is the predominant finding I-GSD. Hyperlipidemia, which is commonly seen in I-GSD, may also accelerate the glomerular sclerosing process.

Reperfusion after brief ischemia disrupts the microtubule network in canine hearts

Histological changes in the stunned myocardium are believed to be minimal. This study examined whether cytoskeletal structures of microtubules are disrupted in the stunned myocardium. In 38 dogs, the left anterior descending coronary artery was occluded for 15 minutes and reperfused to produce the stunned myocardium. Microtubules were stained immunohistochemically. In intact myocardium, microtubules appeared as a filamentous network throughout the cytoplasm and encircled the nucleus. This pattern was not affected by 15 minutes of ischemia. One hour of reperfusion, however, disrupted microtubular structure substantially (disruption score in the endocardium, 53.4 +/- 6.0%) although actin filaments remained intact. Microtubular structures were reconstituted 1-3 days after reperfusion, showing supernormal immunoreactivity. Five days after reperfusion, the pattern of microtubular staining was normal. In another protocol, the role of Ca2+ during reperfusion in microtubular disruption was examined. When intracoronary infusion of EDTA (1.67 mumol/kg body wt per minute) was performed during the initial 10 minutes of reperfusion, myocardial stunning was attenuated. The fractional shortening in the perfused area after 1 hour of reperfusion was 20.1 +/- 1.2% versus 11.5 +/- 0.5% in the control condition (p < 0.05), and the microtubular disruption score was lower (12.6 +/- 1.4%). Although intracoronary infusion of calcium chloride (9 mumol/kg body wt per minute) for 10 minutes in nonischemic hearts increased contractile function (fractional shortening, 25.3 +/- 2.0%), it severely disrupted microtubular networks (microtubular disruption score, 64.0 +/- 10.6%). We conclude that microtubules supporting the structural integrity of myofibrils and other organelles are reversibly disrupted by reperfusion after brief ischemia probably through calcium overload.

A case of secondary aldosteronism similar to Bartter's syndrome with no abnormality in renal chloride reabsorption

We had a 20-year-old male patient of secondary aldosteronism similar to Bartter's syndrome, which had proved to be evident after the remission of nephrotic syndrome. In the patient, hypokalemic alkalosis and hyperreninemic hyperaldosteronemia were observed, although the blood pressure was normal. Hyperplasia of juxtaglomerular cells was observed and no abnormalities indicating either glomerulonephritis or renal artery stenosis were found; the pressor response to intravenously infused angiotensin (ang) II was markedly decreased; urinary prostaglandin (PG) E2, kallikrein and kinin excretion were elevated. The inhibition of PG synthesis with indomethacin decreased renal PG production and partially corrected both hypokalemia and pressor responsiveness to ang II. Thus, this case is considered to be a case of Bartter's syndrome. Contrary to the previously reported observations, the effective fractional chloride reabsorption rate in the renal distal tubules was normal (> 80%) and not changed by PG inhibition. Plasma atrial natriuretic peptide level was normal. An interaction between renin-angiotensin and PG systems appears to play a prior role in this case. To explain the pathophysiology, we have hypothesized an abnormal function of ang II receptor signal transduction which excessively stimulates PLA2, resulting in overproduction of PG synthesis in tissues.