Biomedical subjects

J Hao

Publications and source records attributed to J Hao.

At least 19 recordsLinked to original sources

PubMed2000

Intracerebroventricular infusion of nerve growth factor induces pain-like response in rats.

New strategies have recently been developed where infusion of neurotrophic factors into the brain can rescue different neuronal populations. However, negative side effects have been observed in clinical trials infusing nerve growth factor (NGF) into the lateral ventricle in man, namely pain. Little is known about pain behavior in animals after intracerebroventricular (i.c.v.) neurotrophic injections. Thus, we have examined the effects of i.c.v. infusion of NGF for 2 weeks on the behavioral response of rats to mechanical, cold and heat stimulation. Seven micrograms/day of NGF elicited a significant decrease in vocalization threshold to mechanical stimulation and a significantly increased response to cold and heat stimuli as compared with control. The concentration of NGF in cerebrospinal fluid (CSF) was significantly increased as compared with non-allodynic rats. The enhanced responses to mechanical and heat, but not to cold, stimulation were significantly reduced by CP-99994, a selective antagonist to tachykinin NK-1 receptors. When NGF was infused into the brain parenchyma (striatum, cortex and septum) no allodynic nor hyperalgesic responses could be detected. These results indicate that in rats i.c.v. but not intraparenchymal infusion of NGF induce mechanical and cold allodynia as well as heat hyperalgesia, which is mediated, at least in part, by activation of NK-1 receptors.

Animals↗

PubMed2000

Soft-mode hardening in SrTiO3 thin films

Understanding the behaviour of the dielectric constant in ferroelectric thin films remains a challenging problem. These ferroelectric materials have high static dielectric constants, and so are important for their applications in high-storage-density capacitor structures such as dynamic random access memory (DRAM). But the dielectric constant tends to be significantly reduced in thin films, thereby limiting the potential benefit of ferroelectrics for memory devices. Extensive studies have shown that this phenomenon could be caused by a 'dead layer' of very low dielectric constant between the ferroeletric film and the electrode. And, although very few direct measurements are in fact available, it has been recognized that the lattice dynamical properties in the thin films should also play a key role in the reduction of the dielectric constant. Here we report far-infrared ellipsometry and low-frequency dielectric measurements in SrTiO3 thin films, which demonstrate that the Lyddane-Sachs-Teller relation between the optical-phonon eigenfrequencies and the dielectric constant is fully maintained, as is the case in the bulk material. This indicates that the dramatic reduction of the dielectric constant is a consequence of a profound change of the lattice dynamical properties, in particular of the reduced softening of its lowest optical-phonon mode. Our results therefore provide a better understanding of the fundamental limitations of the dielectric constant values in ferroelectric thin films.

Journal Article↗

PubMed2000

Critical loads of acidity for surface waters in China.

For further control of acid rain and sulphur dioxide pollution, the Chinese government has designated the Acid Rain Control Zone and the Sulphur Dioxide Pollution Control Zone for those areas that are, or could become, affected by acid deposition or ambient sulphur dioxide concentrations. One of the most important principles for designating the Acid Rain Control Zone is that the critical load is exceeded by the sulphur deposition. Through the steady-state water chemistry method (SSWC), critical loads of acidity for surface waters were mapped based on available data. Results show that surface waters sensitive to acid deposition, i.e. surface waters with low critical loads, are mainly found in north-east China, on the Tibetan Plateau, and in north-west China. Compared with the critical loads of soils, critical loads of surface waters are usually higher in almost all areas in China. The reason for very low critical loads of surface waters in some regions dominated by soils geologically not sensitive to acid deposition may be attributed to the low temperature, high altitude and low runoff. In contrast, surface waters in south China are not susceptible to acid deposition, and so far acidification of surface water has not been found in spite of the heavy acid rain. As can be seen from the critical load exceedance map, nearly 10% of the surface waters are subject to risk of acidification in 1995.

Acid Rain↗

PubMed2000

Increased interleukin-8 (IL-8) expression is related to aseptic loosening of total hip replacement.

Aseptic loosening is an increasing problem in total hip replacement (THR). Chronic inflammatory reaction against implant wear particle results in collageno- and osteolysis, leading to loosening of the implant. Cytokines are known to play a major role in this particular inflammatory process. The aim of the present study was to examine interleukin-8 (IL-8) in the synovial-like interface membrane (SLIM) and pseudocapsular tissue of THRs and to compare it to normal knee synovial membrane. Eleven patients suffering from aseptically loosened THRs were included. All the SLIM and pseudocapsular tissue samples were obtained during revision operations. Ten control samples of normal synovium were collected per arthroscopy from the superior recessus of the knee. For immunohistochemical IL-8 detection, polyclonal mouse anti-human immunoglobulin (Ig)G1 IL-8-primary antibody was used with the alkaline phosphatase anti-alkaline phosphatase (APAAP) method. Results were quantitated using the Vidas image analysis system. The highest count levels (mean +/- SEM) were detected in SLIM tissue (386+/-82 cells/mm2). The difference was statistically significant compared with pseudocapsular tissue (193+/-36 cells/mm2) and control samples (18+/-5 cells/mm2). Count levels in control tissue were on average 5% of the SLIM tissues values. The present study determines for the first time the cellular origin of IL-8 in aseptically loosened THRs and also quantitates the IL-8-producing cells in the periprosthetic tissue. The results reveal a high rise in IL-8 concentration in SLIM and in synovial tissues. This finding moves us one step forward in solving the complex network of multiple factors affecting loosening of hip implants.

Adult↗

PubMed2000

Effect of chronic AT(1) receptor blockade on cardiac Smad overexpression in hereditary cardiomyopathic hamsters.

OBJECTIVE: As the pharmacological suppression of angiotensin has been associated with cardioprotective effects in cardiomyopathy, our primary aim was to determine whether the expression of Smad protein components of the cardiac TGF-beta signaling cascade is modulated by chronic AT(1) receptor blockade. Furthermore, we examined the relationship between cardiac Smad protein expression and altered collagen turnover in the cardiomyopathic heart. METHODS: Male UM-X7. 1 cardiomyopathic (CMP) Syrian hamsters at early (65 days) and late (200 days) stages of cardiomyopathy were subjected to 4 week losartan (15 mg/kg/day) treatment. Expression of left ventricular (LV) receptor-activated (Smad 2) and common-mediator (Smad 4) Smads from control (F1-beta strain) hamsters, non-treated cardiomyopathic (CMP), and losartan-treated CMP animals was assessed. Collagen turnover, including fibrillar collagen synthesis/accretion and cardiac MMP activity was assessed. RESULTS: Elevated mRNA abundance of fibrillar collagens and ANF were present in cardiomyopathic hearts and these trends were normalized in the early stage losartan-treated group. 4-Hydroxyproline and zymographic assays confirmed fibrosis and elevated MMP-1 and -2 activities in CMP hearts. Losartan treatment was associated with a modest reduction of cardiac 4-hydroxyproline concentration, and a significant reduction of both MMP-1 and MMP-2 activities. While TGF-beta(1) mRNAs were elevated in both CMP groups vs. controls, total TGF-beta protein content was not different in CMP vs. controls. In LV preparations containing nuclear extract, elevated Smad 2 and Smad 4 protein expression was noted in cardiomyopathic hearts vs. controls. Losartan treatment of late-stage CMP hamsters was associated with a significant reduction in Smad 2 and a modest reduction of Smad 4 protein expression vs. untreated CMP samples. CONCLUSIONS: Altered cardiac Smad expression, present in both early and late stage cardiomyopathy, is positively correlated with the occurrence of cardiac fibrosis and elevated collagen turnover in failing CMP hearts. Four week AT(1) blockade is associated with normalized expression of cardiac Smad 2 proteins, and these changes occur in parallel with some aspects of collagen turnover in failing cardiomyopathic hearts.

Analysis of Variance↗

PubMed1999

Genetic studies on a family with acute myelogenous leukemia.

Seven cases of myelogenous leukemia--two acute erythroleukemia (AEL), four acute myelogenous leukemia (AML), and one acute myelomonocytic leukemia (AMMoL)--were found in 22 members of three consecutive generations of a family in the past 16 years (1973-1989). By using cytogenetic, hematologic, and biochemical analyses of those surviving in this family, we also found four members who might develop leukemia in the future. Southern blot analysis of one of the four members and her father (an acute leukemia patient) with a v-ERBB probe showed that the gene abnormalities consisted of a c-ERBB rearrangement (hereditary) and a rearrangement/amplification of the same gene.

Blotting, Southern↗

PubMed1999

Elevation of expression of Smads 2, 3, and 4, decorin and TGF-beta in the chronic phase of myocardial infarct scar healing.

We have previously shown that non-myocytes present in healed 8-week infarct scar overexpress transduction proteins required for initiating the elevated deposition of structural matrix proteins in this tissue. Other work suggests that TGF-beta 1 may be involved in cardiac fibrosis and myocyte hypertrophy. However, the significance of the altered TGF-beta signaling in heart failure in the chronic phase of post-myocardial infarction (MI), particularly in the ongoing remodeling of the infarct scar, remains unexplored. Patterns of cardiac TGF beta 1 and Smad 2, 3, and 4 protein expression were investigated 8 weeks after MI and were compared to relative collagen deposition in border tissues (containing remnent myocytes) and the infarct scar (non-myocytes). Both TGF-beta 1 mRNA abundance and protein levels were significantly increased in the infarct scar v control values, and this trend was positively correlated to increased collagen type I expression. Cardiac Smad 2, 3, and 4 proteins were significantly increased in border and scar tissues v control values. Immunofluorescent studies indicated that Smad proteins localized proximal to the cellular nuclei present in the infarct scar. Decorin mRNA abundance was elevated in border and infarct scar, and the pattern of decorin immunostaining was markedly altered in remote remnant heart and scar v staining patterns of control sections. Expression of T beta RI (53 kDa) protein was significantly reduced in the scar, while the 75 kDa and 110 kDa isoforms of T beta RII were unchanged and significantly increased in scar, respectively. These results indicate that TGF-beta/Smad signaling may be involved in the remodeling of the infarct scar after the completion of wound healing per se, via ongoing stimulation of matrix deposition.

Activin Receptors, Type I↗

PubMed1999

Expression of Gi-2 alpha and Gs alpha in myofibroblasts localized to the infarct scar in heart failure due to myocardial infarction.

OBJECTIVE: Patients surviving large transmural myocardial infarction (MI) are at risk for congestive heart failure with attendant alteration of ventricular geometry and scar remodeling. Altered Gi-2 alpha and Gs alpha protein expression may be involved in cardiac remodeling associated with heart failure, however their expression in scar tissue remains unclear. METHODS: MI was produced in Sprague-Dawley rats by ligation of the left coronary artery. Gi-2 alpha and Gs alpha protein concentration, localization and mRNA abundance were noted in surviving left ventricle remote to the infarct, in border and in scar tissues from 8 week post-MI hearts with moderate heart failure. RESULTS: We observed a 4.5- and 5.0-fold increase in immunoreactive Gi-2 alpha protein concentration occurs in the border and scar regions vs. control values, respectively, in 8-week post-MI rat hearts. Similarly, immunoreactive Gs alpha protein concentration was increased 3.4- and 8.2-fold, respectively, in these tissues vs. controls. Double-fluorescence labeling and phenotyping studies revealed that both Gi-2 alpha and Gs alpha proteins were localized to myofibroblasts in the infarct scar and to viable myocytes bordering the scar. Northern analysis revealed that the Gi-2 alpha/GAPDH ratio was increased in both viable and scar regions (1.24- and 1.85-fold respectively) from experimental hearts when compared to sham-operated control values when compared to noninfarcted left ventricle, the value of this ratio in scar tissue was elevated approximately 1.5 fold. The Gs alpha/GAPDH ratio was significantly increased (1.28-fold) only in the scar region vs. control. CONCLUSION: Our results indicate a marked increase in the expression of Gi-2 alpha and Gs alpha from myofibroblasts of the infarct scar as well as remnant myocytes bordering the scar in 8-week post-MI rat hearts. We suggest that these changes may be associated with ongoing remodeling in the infarct scar in chronic post-MI phase of this experimental model.

Analysis of Variance↗

PubMed1998

Antiproliferative and antifibrotic effects of mimosine on adult cardiac fibroblasts.

Prolyl 4-hydroxylase catalyzes the hydroxylation of collagen pro-alpha chains for the deposition of cardiac collagen. The effect of prolyl 4-hydroxylase on synthesis and degradation of collagen was studied in cultured adult cardiac fibroblasts using mimosine, a prolyl 4-hydroxylase inhibitor. Mimosine inhibited [3H]thymidine incorporation in cultured fibroblasts in a dose-dependent manner (100-600 microM). Immunofluorescence in fibroblasts and biochemical detection of mature type I collagen in culture serum revealed a strong inhibition of synthesis and secretion of mature collagens, respectively, in the presence of 200 microM mimosine. Western blot analysis for procollagen was carried out in cultured fibroblasts, and 200 microM mimosine treatment was associated with increased intracellular accumulation of procollagen from 4.14+/-0.27 to 10. 19+/-0.37 (arbitrary units). Immunofluorescence studies confirmed a marked increase of intracellular procollagens in fibroblasts treated with mimosine, which suggests a loss of coordinated monomeric procollagen synthesis and secretion of triple helical mature collagens. Modest inhibition of collagen type I mRNA abundance was observed in mimosine-treated fibroblasts, whereas no effect was noted for mRNAs of collagen type III, alpha-prolyl 4-hydroxylase or beta-prolyl 4-hydroxylase when compared to untreated control values. Treatment of fibroblasts with 200 microM mimosine was associated with elevation of matrix metalloproteinase (MMP)-9 activity. The cytotoxicity of mimosine treatment was found minimal at the concentrations indicated above. Thus the antifibrotic effects induced by mimosine on cultured adult cardiac fibroblasts was associated with inhibition of prolyl 4-hydroxylase and diminished extracellular secretion of procollagen, despite the reactive elevation of intracellular procollagen synthesis. We suggest that specific inhibition of prolyl 4-hydroxylase may provide a novel therapeutic approach for the modulation of cardiac fibrosis.

Animals↗

PubMed1998

Visualization of penicillin-binding proteins during sporulation of Streptomyces griseus.

We used fluorescein-tagged beta-lactam antibiotics to visualize penicillin-binding proteins (PBPs) in sporulating cultures of Streptomyces griseus. Six PBPs were identified in membranes prepared from growing and sporulating cultures. The binding activity of an 85-kDa PBP increased fourfold by 10 to 12 h of sporulation, at which time the sporulation septa were formed. Cefoxitin inhibited the interaction of the fluorescein-tagged antibiotics with the 85-kDa PBP and also prevented septum formation during sporulation but not during vegetative growth. The 85-kDa PBP, which was the predominant PBP in membranes of cells that were undergoing septation, preferentially bound fluorescein-6-aminopenicillanic acid (Flu-APA). Fluorescence microscopy showed that the sporulation septa were specifically labeled by Flu-APA; this interaction was blocked by prior exposure of the cells to cefoxitin at a concentration that interfered with septation. We hypothesize that the 85-kDa PBP is involved in septum formation during sporulation of S. griseus.

Anti-Bacterial Agents↗

PubMed1997

Determination of Association Constants for Cyclodextrin-Surfactant Inclusion Complexes: A Numerical Method Based on Surface Tension Measurements

Inclusion complexes of beta-cyclodextrin (beta-CD) with sodium octyl sulfonate (C8As), sodium dodecyl sulfonate (C12As), and sodium hexadecyl sulfonate (C16As) in aqueous solutions are studied by surface tension measurement at the air/water interface at different temperatures. At fixed concentrations of the surfactants, the surface tension increases with an increase in beta-CD concentration to a maximum value, at which it holds. The surface tension curves of the surfactants in the presence of beta-CD are higher than those in the absence of beta-CD. The curves rise higher with the increase in beta-CD concentration for each surfactant. The apparent critical micelle concentrations (CMC*) of the surfactants vary linearly with beta-CD concentration. The CMC* and surface tension values (including those after the CMC*) for the same system decrease with increase in temperature. A numerical method based on surface tension measurements is developed to determine the association constants for 1:1 inclusion complexes. This method is very reliable and easy to perform. The results demonstrate that the longer the hydrophobic tail of the surfactant, the greater the association constant with beta-CD, and that for the same surfactant the association constant is higher at lower temperatures.

Journal Article↗

PubMed1997

Mineralized nodule formation by human dental papilla cells in culture.

Human dental papilla cells were enzymatically separated from deciduous tooth germs of an 8-month-old embryo legally aborted. The second passage cells were cultured up to 35 days in 3 groups. The beta-GP group was cultured in the Dulbecco MEM containing ascorbic acid and beta-glycerophosphate supplemented with 15% fetal bovine serum. The Dex group was in the same medium, in addition containing dexamethasone. The control group contained none of the 3 chemicals. Mineralized nodules were formed after 15 days in the beta-GP and Dex groups. Only in the presence of ascorbic acid and organic phosphate did they mineralize. The addition of dexamethasone caused a significant increase in the number of nodules. By electron microscopy, the nodules contained needle-shaped crystals associated with a network of collagen fibrils. Calcium and phosphorus were detected by energy-dispersive X-ray microanalysis in the nodules. Furthermore, the crystalline material exhibited a pattern consistent with hydroxyapatite and dentin when examined by X-ray diffractometry. Cells showed high levels of alkaline phosphatase activity, which was increased 2-3 times in the presence of the 3 chemicals. These results indicated that human dental papilla cells have the ability to form dentin in culture. The formation of mineralized nodules by human dental papilla in vitro provides a useful model for studying the morphogenesis and differentiation of dental papilla ectomesenchyme.

Alkaline Phosphatase↗

PubMed1997

[Reoperations on prosthetic heart valves: an analysis of 64 cases].

During the period of Fabruary 1988 to May 1996, 64 reoperations were performed for prosthetic valve malfunction. Degeneration of bioprosthesis occurred in 46 patients, failure of mechanical prosthesis in 9, and periprosthetic leakage without evidence of infection in 9. In accordance with the status of cardiac function, 9 patients with acute dysfunction of mechanical prosthesis received emergency operations, and the remaining 55 patients with bioprosthetic valve failure or periprosthetic leakage received selective operation. There were 8 early deaths with a overall hsopital mortality rate of 12.5%. Three of the deaths occurred among the 55 selective procedures for a mortality of 5.3% and 3 of the deaths occurred among the 9 emergence procedures for mortality of 33.3%. The 56 long-term survivors were followed up from 3 months to 7 years (mean 2.1 years). There were 3 late deaths (5.3%). Forty-eight patients have been living more than 1 year. Their cardiac function after reoperation was class I (42 patients), class II (5), and class III (1). The timing of reoperation and surgical technique were discussed.

Adult↗

PubMed1997

[Clinical study on myxoma and chordoma in the skull base].

OBJECTIVE: The clinical manifestation, neuroimaging properties, and pathologic changes of myxoma and chordoma were studied. METHODS: Their neuroimaging properties and pathologic changes of myxoma 7 cases and chordoma 13 cases were analyzed. RESULTS: (1) Clinical manifestation: the injury of oculomotor nerve and exorbitism is dominant in myxoma, but the injury of posterior cranial nerves is dominant in chordomas. (2) Plain skull X-ray film: local irregular punctate calcification and osseous necrosis were common in myxoma. Clivus invasion moruloid calcification and cauliflower-like calcification are always seen in chordoma. (3) CT and MRI: Location of the tumor and their relations with the adjacent structure were clear. (4) Pathologic changes: Cells are punctately arranged in myxoma, and vesicularly arranged in chordoma. CONCLUSION: The clinical study of myxoma and chordoma is not only useful for their differiental diagnosis, but can provide valuable clues for their surgical approach as well.

Adolescent↗

PubMed1997

Differential expression of cytokeratin mRNA and protein in normal prostate, prostatic intraepithelial neoplasia, and invasive carcinoma.

The expression of cytokeratin (CK) mRNA for CK5, -8, -14, -16, and -19 was investigated in normal prostate, prostatic intraepithelial neoplasia (PIN) lesions, and invasive carcinoma using in situ hybridization. Protein localization was carried out in adjacent sections using immunohistochemistry and correlated with mRNA expression. Snap-frozen human prostate samples including 22 examples of normal glands, 20 cases of PIN lesions, and 12 cases of invasive carcinoma were examined. CK5 and -14 mRNA and protein were prominently expressed only in the basal cells of normal glands and PIN lesions. CK14 mRNA was absent in the luminal cells of the most of the PIN lesions but was seen at a low level in some PIN lesions. CK14 protein was not detected in any PIN lesion, suggesting that, if the cell that makes up the PIN lesions is derived from a basal cell, CK14 translation is depressed although a low level of CK14 mRNA may persist. CK8 mRNA and protein were constitutively expressed in all epithelia of normal and abnormal prostate tissues. CK19 mRNA and protein were persistently expressed in both basal and luminal cells of the tubular portion of normal glands as well as PIN lesions, but were expressed heterogeneously in both basal and luminal cells of normal alveoli. CK16 mRNA was expressed in a similar pattern as CK19, but CK16 protein was not detected either in normal or in abnormal prostate tissues. In conclusion, the expression of CK19 in PIN lesions is similar to its tubular expression and would support an origin of PIN lesions from this structure rather than the alveolar portion of the glands. The similar cytokeratin expression between PIN lesions and invasive carcinoma further supports the concept that PIN is a precursor lesion of invasive carcinoma.

Carcinoma↗

PubMed1997

[Studies on GBV-C infection in blood donors in four provinces of China].

Plasma antibody against GBV-C (anti-GBV-C) and GBV-C RNA were detected with enzyme immunoassay (EIA) and reverse transcription nested polymerase chain reaction (RT-nPCR) in blood donors to study the prevalence of GBV-C infection in blood donors. Positivity of anti-GBV-C was 4.92 percent in 1,200 plasma donors (59/1,200), and that of GBV-C RNA was 64.41 percent in those with positive anti-GBV-C (38/59). Positivity of anti-GBV-C was 2.86 percent in 350 whole blood donors (10/350) and that of GBV-C RNA was 60.00 percent in those with positive anti-GBV-C (6/10). Positive rate of anti-GBV-C in those who donated blood for more than 10 years was higher than in control group. It suggests that infection with GBV-C was more often in plasma and blood donors. There were blood donors with positive GBV-C RNA but normal ALT activities and those both positive in GBV-C RNA and HCV RNA. It is urgent to detect the markers of GBV-C infection in blood donors as soon as possible.

Adolescent↗

PubMed1996

Differential expression of laminin 5 (alpha 3 beta 3 gamma 2) by human malignant and normal prostate.

Laminin 5 is an extracellular matrix protein integral to the formation of the hemidesmosomes that attach normal basal cells to the underlying basal lamina. We have shown that these hemidesmosomal complexes are lost in prostate carcinoma, possibly allowing malignant cells to detach from the anchoring structures and then to invade and migrate through the adjacent tissue. Our previous immunohistochemical studies of normal and malignant human prostate tissue demonstrated that the laminin subchains alpha 1, alpha 2, beta 1, beta 2, gamma 1, and gamma 2 were all expressed as normal components of the basal lamina surrounding prostate glands. Although most of these subchains were also expressed by the de novo basal lamina synthesized by prostate carcinoma, the gamma 2 subchain of laminin 5 was not detected. In an effort to investigate the role laminin 5 plays in the tumorigenesis of prostate carcinoma, the protein expression of the three subchains of laminin 5 (alpha 3, beta 3, and gamma 2) was compared in normal prostate, prostatic intraepithelial neoplasia, and invasive carcinoma using immunohistochemistry. The results showed that the protein for the alpha 3 subchain of laminin 5 is retained by both normal prostate epithelium and prostate carcinoma, but the beta 3 and the gamma 2 subchains were not detected in invasive carcinoma. Despite the absence of the gamma 2 protein, however, the carcinoma cells continued to express substantial amounts of the gamma 2 mRNA. Although it is unclear how the gene for the gamma 2 subchain of laminin 5 is regulated, results of this study suggest that there is a post-transcriptional defect in the expression of the gamma 2 subchain that occurs during the progression from a premalignant lesion to invasive carcinoma. As laminin 5 is a component of the anchoring filaments, the failure to express the gamma 2 subchain may contribute to the failure to form anchoring filaments and hemidesmosomes. This failure of hemidesmosome formation results in a less stable epithelial-stromal junction, which may allow malignant cells more potential to invade and spread through adjacent structures.

Blotting, Northern↗

PubMed1996

Differences in pituitary expression of proopiomelanocortin in Dahl salt-resistant and salt-sensitive rats on a high salt diet.

The Dahl strain of genetically salt resistant (R) and salt sensitive (S) rats affords an opportunity to explore mechanisms for salt resistance and sensitivity. Because of the evidence that opioid peptides and their receptors can be involved in cardiovascular regulation, the objective of this study was to test the hypothesis that proopiomelanocortin (POMC), the precursor of beta-endorphin, is involved in the development of hypertension, through the determination of POMC mRNA in the pituitary. Three-week-old inbred Dahl R and S rats were maintained on a high salt diet (8% NaCl) or low salt diet (0.4% NaCl) for 6 weeks. POMC mRNA and for comparison preproenkephalin A (preproENK) mRNA were examined from tissues of Dahl R and S rats as determined by Northern blot analysis using beta-actin as an internal standard. POMC mRNA was abundant in the pituitary tissues. There was more POMC mRNA in the pituitary tissue of R rats compared with that of S rats on the high salt diet. Differences in POMC mRNA in the pituitary were not observed between R and S on the low salt diet. There were no differences in the levels of preproENK mRNA in the pituitary tissues of R and S rats on high or low salt diet. From these data, we propose that inefficient production of POMC mRNA is a characteristic of the Dahl S rat on a high salt diet.

Animals↗