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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the involvement of peripheral catecholamines in the development of Dahl-Iwai salt-sensitive (DIS/Eis) hypertension, we performed immunohistochemical staining of tyrosine hydroxylase (TH) in the superior cervical ganglia (SCG) of DIS/Eis rats and Dahl-Iwai salt-resistant (DIR/Eis) rats, and in situ hybridization histochemistry for demonstration of TH mRNA localization in the SCG of these rats. DIS/Eis and DIR/Eis rats were fed on a high (8%) salt diet or on a low (0.3%) salt diet for 4 weeks. Nerve cells in the SCG of DIS/Eis high salt rats exhibited more intense TH-immunoreactivity (P < 0.01) and hybridization signals (P < 0.01) than those of the other experimental groups. These findings suggest that activation of peripheral sympathetic nerves may account for hypertension in DIS/Eis rats on a high salt diet.
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PMID:Effect of dietary NaCl on tyrosine hydroxylase in the superior cervical ganglia of Dahl rats. 762 44

Dahl-Iwai salt-sensitive (S) and salt-resistant (R) rat strains were established as inbred strains at Brookhaven National Laboratory, NY, and were introduced into Eisai Co., Ltd., Japan, and designated DIS/Eis and DIR/Eis. To examine whether there are different allele distributions among the substrains of inbred Dahl S and R rats, we determined biochemical and immunological alleles of DIS/Eis and DIR/Eis, and SS/Sea and SR/Sea, which were derived from SS/Jr and SR/Jr, which were developed by Rapp and Dene. Several differences of allele distribution were observed, indicating that the substrains have different genetic backgrounds. The phenotypic differences between the substrains, such as the severity of the hypertension induced, could be ascribed to the different genetic backgrounds.
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PMID:Genetic profiles of newly inbred Dahl/Iwai salt-sensitive and salt-resistant rats. 916 Jul 89

GENETIC DISEASE MODELS: A certain proportion of hypertension cases are due to renal disease. Recent advances in genetics has improved our knowledge of the pathophysiological mechanisms involved in certain rare diseases including apparent overproduction of mineralocorticoids, Liddle syndrome and Gitelman syndrome, and to hypothesize on the mechanism of primary hypertension. EFFECT ON PROGNOSIS: Onset of renal disease in hypertensive patients, whether expressed by proteinuria or the early stages of renal failure, worsens cardiovascular prognosis. FREQUENCY OF RENAL DISEASE: Renal disease is relatively rare in hypertensive patients, but as the general hypertensive population becomes older, there is a considerable rise in the prevalence of hypertensive renal disease as the underlying cause leading to dialysis. The risk of progressing to renal failure appears to be related to the level of the blood pressure, especially systolic pressure, at disease onset. Hypertension black subjects have a higher risk of developing chronic renal failure. THERAPEUTIC BENEFIT: Several studies have shown that lowering blood pressure with antihypertensive drugs lowers the risk progressing with primary hypertension.
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PMID:[Renal involvement in essential arterial hypertension]. 920 91

ALTERATIONS OF THE ENDOTHELIUM: Because of its anatomic position between circulating blood and smooth muscle cells, the vascular endothelium is a prime target for cardiovascular diseases such as hypertension, hypercholesterolemia, diabetes or ischemia. The morphological changes occurring in the endothelium have been known for many years, but it was only recently that the functional alterations have been described. IMPACT OF NO: Under physiological conditions, the vascular endothelium plays a protective role by secreting relaxation factors. In the disease state, the synthesis and release of NO may be reduced or even abolished. The exact significance of endothelium-dependent vasodilatation disorders remains a topic of research, but the properties of NO strongly suggest it is involved in several diseases. For some diseases it is still a question as to whether the observed anomalies are the cause or the consequence of the underlying disease. DISEASE-SPECIFIC CHANGES: NO is known to be reduced in atherosclerosis, either because of less synthesis or accelerated degradation. In different experimental modules of hypertension, the baseline level of NO release appears to be decreased. Conversely, NO release can be normal, reduced or increased in diabetes. In heart failure, there appears to be not only a permanent alteration in NO secretion, but also an increase in factors stimulating vascular contraction, contributing to an altered capacity for vascular adaptation in these patients.
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PMID:[Nitric oxide (NO), vascular protection factor. NO related cardiovascular diseases]. 976 31

To investigate the effects of ascorbic acid deficiency on the pathogenesis of hypertension and/or its complications, we established a rat strain with both genetic hypertension and a defect of ascorbic acid biosynthesis. The od gene (L-gulono-gamma-lactone oxidase gene) of the ODS (Osteogenic Disorder Shionogi) rat, which is a rat mutant unable to synthesize ascorbic acid, was introduced into spontaneously hypertensive rats (SHR), and a novel congenic strain, SHR-od, was established. SHR-od showed scurvy when fed an ascorbic acid-free diet. Systolic blood pressure of male SHR-od began to increase at 9 weeks of age and reached 190-200 mmHg at 20 weeks of age. In 25-week-old SHR-od, ascorbic acid deficiency when fed an ascorbic acid-free diet for 6 weeks caused a remarkable reduction of blood pressure to lower than 110 mmHg. The wall to lumen ratio of the testicular artery in ascorbic acid-deficient SHR-od was lower than that of the control rats. When rats were fed a diet supplemented with ascorbic acid (300 mg/kg), ascorbic acid concentration in SHR-od was lower in the serum and liver than that in ODS rats. These results indicate that ascorbic acid could be closely related to the development of hypertension in SHR-od. We believe that SHR-od will be a useful model for experimental studies on hypertension and its complications, since all of them suffer from hypertension spontaneously and the level of ascorbic acid deficiency in these rats could be controlled at will both in concentration and duration.
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PMID:A newly established strain of spontaneously hypertensive rat with a defect of ascorbic acid biosynthesis. 1169 68

Clinical and experimental evidence suggest an involvement of dopamine systems, mainly the mesocorticolimbic one (MCL), in Attention-Deficit Hyperactivity Disorder (ADHD). However, it remains to be ascertained whether the systems are hyper- or hypo-functioning, for the implications of the functional state. Indeed, differential functional states of the MCL branches are suggested to be the neural substrate of different ADHD variants. This review covers published and unpublished data from the Naples-High Excitability (NHE) rat, an animal model of ADHD, featuring its main aspects, with no hypertension. Therefore, a multiple approach based on morphological studies of dopamine, norepinephrine, glutamate, acetylcholine and GABA systems, synaptic (Calcium/Calmodulin kinase II) and extrasynaptic (chondroitin sulphates) environments, and molecular biology and pharmacological studies on the dopamine system has been carried out. Morphological findings suggest dopamine neurons in the Ventral Tegmental Area (VTA) to be hypertrophic in NHE rats. The mesostriatal and mesolimbic dopamine branches appear to be normal in basal conditions. However, the striatal interface is probably defective following activation. Conversely, the prefrontal cortex, which represents the second main target of VTA dopamine neurons, has many alterations at the basal level. Therefore, the emerging picture is the association of a hyperinnervating and hyperfunctioning mesocortical branch of the dopamine system. Thus, the evidence gathered so far might improve our understanding of the neural substrates of neuropsychiatric disorders such as ADHD, schizophrenia and drug addiction.
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PMID:Behavioural, pharmacological, morpho-functional molecular studies reveal a hyperfunctioning mesocortical dopamine system in an animal model of attention deficit and hyperactivity disorder. 1462 12

Symptoms of balance disorders including 'unsteadiness', 'dizziness and vertigo' are common in the elderly and commonly found in general practice in medicine. There are many causes of balance disorders and vary from one person to another. Disorder of the internal ear or vestibular end-organ type is one cause. Unsteadiness of somato-sensory or proprioception is common in the elderly so is degenerative disorder of central control in brain. The elderly are prone to many chronic illnesses or disorders which are causes of balance disorder or give rise to more rapid degeneration of the central nervous system i.e. high blood pressure, diabetes mellitus, heart disease, proprioception and joint problems, arthritis and muscular weakness due to lack of good health and exercise. The objectives of this research study were to find the etiologies of balance disorders and how Balance Exercises and the 'National Health Service' can be of benefit in helping to prevent them. 1565 elderly inhabitants (age > or = 60 years) of 20 communities adjacent to Siriraj Hospital were selected for study. Among these, 625 persons had a history of balance disorders. Among those, 256 had symptoms during the week selected for examination. The average age was 66 years old, women outnumbered men with a ratio of 2.4:1. The common underlying causes were hypertension in 32.4%, diabetes mellitus 13.8%, arthritis 8.1%, and heart disease 4.4% respectively. All are still taking one or more types of drug. The subjects were randomly divided into two groups for the study purpose of effectiveness of balance exercise. Group 1 did not perform the head balance exercise and Group 2 performed the head balance exercise. Audiometric testing showed impaired hearing in 90% of the subjects. The majority slowed hearing loss in high frequencies. Testing of middle ear function found 75% of Group 1 to have normal middle ear function 77% of Group 2. Brainstem Electrical Response Audiometry (BERA) showed normal response latencies of in 96% of group 1 and 94% of Group 2. Poor morphology of waveform was found in 12% of Group 1 and 16% of Group 2. Doppler sonography for intra-cranial blood flow measurement showed abnormal flow of the ICA in 17.6% of group 1 and 20.16% of group 2. Basilar arterial abnormal flow was found in 77.6% of Group 1 and 80.6% of Group 2 respectively. The flow of ICA was improved after 8 weeks in both groups. The measurement of balance by Posturography showed 86.7% abnormality in Group 1 and 83.5% abnormality in Group 2 (and the majority due to inner ear problems but many cases had a mixture of joints and CNS problems too). Results of the self-evaluation (by questionaires) showed the elderly to have symptoms of light headedness in 51% and loss of balance in 29%, Vertigo with rotation occurred in 23.6%. 49% of the symptoms were intermittent, 56.4% experienced a 'fall". On questioning about the benefit and performance of Head and Neck Exercises, 82.8% found the exercises were easy to perform, 56.4% said the results were very beneficial.
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PMID:Balance disorders in the elderly and the benefit of balance exercise. 1556 Jul 2

Plasma ascorbic acid is decreased in women with the pregnancy disorder preeclampsia. We used a mutant strain of rats (Osteogenic Disorder Shionogi), dependent on dietary sources of vitamin C, to investigate whether reduced intake of the vitamin would differentially affect vascular function in late-pregnant (day 19) and age-matched virgin rats. The animals were given either 1 mg/mL of ascorbic acid ad libitum in drinking water [fully supplemented (FS)] or 0.25 mg/mL [marginally supplemented (MS)]. Fetal weights were 21% lower in MS than FS rats, whereas mean maternal weights and pup numbers did not differ. Small mesenteric arteries (diameter, 268+/-7 microm) were mounted in a pressurized arteriograph. Myogenic reactivity (contractile response to step increases in intraluminal pressure) was increased in arteries from MS pregnant compared with FS pregnant rats to levels observed in virgin rats. Ascorbic acid intake did not affect myogenic responses of arteries from virgin rats. Hence, the normal pregnancy-induced reduction in myogenic reactivity was abrogated in MS pregnant animals. Inhibition of nitric oxide synthase had no effect on the myogenicity of arteries from virgin or MS pregnant rats but increased myogenicity of FS pregnant rats to the level of MS pregnant rats. Free radical scavengers reversed the accentuated myogenicity of MS pregnant rats without affecting FS pregnant or virgin rat arteries. These data indicate that moderate ascorbate deprivation increases mesenteric artery myogenic responsiveness during pregnancy. This increase may result from a decrease in nitric oxide-mediated modulation of the myogenic contractile response.
Hypertension 2006 Mar
PMID:Moderate ascorbate deficiency increases myogenic tone of arteries from pregnant but not virgin ascorbate-dependent rats. 1643 38

This review summarises the role of the endothelium in the regulation of the vascular tone, emphasizes the importance of nitric oxide and endothelin at the vasodilator and vasoconstrictor physiological processes. Mainly, the nitric oxide is responsible for the basal tone of the vasculature, but plenty of modifying factors (endothelin, angiotensin-II, prostacyclin) have also important effects. Endothelial dysfunction observable in hypertension, which characterised by disorder of the endothelium-dependent relaxation, and predominance of the vasoconstrictor processes. Disorder of synthesis, decreased biological activity and increased degradation of the nitric oxide could play a role in the fall of the basal vasodilator tone, as well as other factors influencing the production of nitric oxide. Due to a relaxation disorder, the vasoconstrictor endothelin come to the front, following morphological changes of the vessels, afterwards. Endothelial dysfunction of the medium size arteries lead to thickening of the intima, what can follow by non-invasive measurements at the common carotid arteries. It is unambiguous in hypertensive patients that augmenting the tone of the resistance vessels, the peripheral vascular tone increases. It is proved in hypertensive adults that damaged function of the cerebral arterioles results in decrease of the vasoreactivity following a hypo- or hypercapnic stimuli. The imbalance of the nitric oxide-endothelin system is not only a process what helps to partly explain the pathophysiology of hypertension, but also a therapeutic aim preventing the process of atherosclerosis.
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PMID:[The role and clinical importance of nitric oxide-endothelin system in hypertension]. 1706 98

The interaction between genes and environment seems to be relevant for the development of Attention Deficit/Hyperactivity Disorder (ADHD), one of the most prevalent childhood psychiatric diseases. The occurrence of ADHD is typically associated with poor academic performance, probably reflecting learning difficulties and/or cognitive impulsiveness. The inbred Spontaneously Hypertensive Rats (SHR) strain has often been considered as an animal model of ADHD, since they 'naturally' display the main ADHD symptomatology. Although pharmacological agents improve SHR's cognitive deficits, little is known about the involvement of environmental factors in SHR disabilities and to what extent 'protective' non-pharmacological factors may be considered as strategy for ADHD prevention. Here we investigated whether the rearing environment during neurodevelopment may counteract later cognitive deficits presented by adult SHR. Wistar (WIS) rats were also used to investigate whether the putative effects of environmental enrichment depend on a specific genetic background. The animals were reared in enriched environment (EE) or standard environment (SE) from the post-natal day 21 until 3 months of age (adulthood) and tested for cognitive and non-cognitive phenotypes. EE improved SHR's performance in open field habituation, water maze spatial reference, social and object recognition tasks, while non-cognitive traits, such as nociception and hypertension, were not affected by EE. Response of WIS rats was generally not affected by the present EE. These results show that the general low cognitive performance presented by SHR rats strongly depends on the rearing environment and they may suggest modifications of the familial environment as a putative preventive strategy to cope with ADHD.
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PMID:Environmental enrichment improves cognitive deficits in Spontaneously Hypertensive Rats (SHR): relevance for Attention Deficit/Hyperactivity Disorder (ADHD). 1954 50


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