Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

By repeated inbreeding, 2 strains of spontaneously hypertensive and normotensive rats have been simultaneously selected. The activities of tyrosine hydroxylase and phenylethanolamine-N-methyltransferase were determined in various central catecholaminergic nuclei (C1, C2, A6 and A9) and in two peripheral tissues (adrenal glands and superior cervical ganglion). These assays were performed on rats belonging to the normotensive or the hypertensive strain at 3 ages which characterize the development of hypertension (5, 9 and 21 weeks). Except for a decrease in the C1 region of 9-week-old rats, no significant change in tyrosine hydroxylase activity occurred in central or peripheral structures of the spontaneously hypertensive rats when compared to the normotensive rats. In contrast, the activity of the phenylethanolamine-N-methyltransferase (PNMT), was increased in the C2 adrenergic group of the medulla oblongata in young spontaneously hypertensive rats: +43% (P less than 0.001) at 5 weeks of age and +32% (P less than 0.001) in 9-week-old rats. However, there was no significant difference between the 21-week-old rats. No modification of the PNMT activity was found in the C1 adrenergic group of the medulla oblongata. PNMT activity was increased significantly in the adrenal glands of 5-week-old hypertensive rats (+22%, P less than 0.001). By 9 weeks, the difference in PNMT activity in the adrenals was no longer significant. Thus, in young rats of the hypertensive strain, there was an increase in the capacity to synthetize adrenaline in the C2 area of the medulla oblongata and in the adrenal glands. While the enzymatic change present in the adrenals seems to be specific to this new strain of hypertensive rats, the elevation of PNMT activity in a specific region of the medulla oblongata (C2 group) is a characteristic common to at least two independently derived strains of genetically hypertensive rats.
 ...
PMID:Early increase in phenylethanolamine-N-methyltransferase activity in a new strain of spontaneously hypertensive rats. 3 64

Dihydralazine treatment which lowered blood pressure in young rats from the Lyon Hypertensive Strain (LHS), did not change phenylethanolamine-N-methyltransferase (PNMT) activity, but decreased tyrosine hydroxylase and dopamine-beta-hydroxylase activities in the C2 medullary region. These data suggest that the increase in PNMT activity, previously described for this strain, is not a consequence of the developing hypertension and that hypotensive treatment could inactivate some catecholaminergic neurons of the medulla oblongata.
 ...
PMID:Dihydralazine and catecholamine-synthesizing enzymes in spontaneous hypertension. 49 52

The activity of the adrenaline-forming enzyme, phenylethanolamine-N-methyltransferase (PNMT) and the levels of the catecholamines dopamine, noradrenaline and adrenaline were determined during the development of the DOCA-salt hypertension in selective areas of the rat brain stem and hypothalamus. Increases in PNMT activity were restricted to the A1 area and locus coeruleus after 2 weeks of DOCA-salt treatment and were extended to the A2 area after 9 weeks of treatment. Adrenaline concentrations were higher in these areas only after 9 weeks of treatment. Noradrenaline levels did not change, except in the nucleus tractus commissuralis. Dopamine levels were unchanged at all times and in all structures studied. These results implicate brain stem adrenaline neurons in the central response which occurs during the DOCA-salt experimental hypertension.
 ...
PMID:Brain catecholamines during development of DOCA-salt hypertension in rats. 50 25

The central noradrenaline (NA) and adrenaline (A) turnover in 15--16-week-old stroke prone, spontaneously hypertensive (sp-SH) female rats in an advanced stage of hypertension was found to differ from that of normotensive Wistar-Kyoto (WKy) control rats. The catecholamine (CA) levels were measured after inhibition of dopamine-beta-hydroxylase (DBH) or phenylethanolamine-N-methyltransferase (PNMT). in the hypertensive rats the dopamine (DA) and NA levels and the NA turnover were reduced in the hypothalamus, while in the dorsal part of the caudal medulla oblongata NA levels and A turnover were reduced. Changes in hypothalamic DA and NA mechanisms and in A mechanisms in medulla oblongata may therefore be of importance in the blood pressure regulation of sp-SH rats.
 ...
PMID:Catecholamine turnover changes in hypothalamus and dorsal midline area of the caudal medulla oblongata of spontaneously hypertensive rats. 53 May 33

Catecholamines and catecholamine-synthesizing enzymes have been examined in specific brain areas during the development of spontaneously (genetic) hypertensive (SH) rats. Changes in catecholamine metabolism were localized to regions of the brain implicated in the regulation of blood pressure. Norepinephrine levels and dopamine-beta-hydroxylase (DBH) activities were decreased in specific nuclei of the hypothalamus and in the nucleus interstitialis striae terminalis ventralis, in both young and adult rats. The decrease in the formation of norepinephrine can result in a reduced activation of central alpha-adrenergic receptors which may be related causally to the onset of hypertension. The activity of the epinephrine-forming enzyme, phenylethanolamine-N-methyltransferase (PNMT), was increased in the A1 and A2 areas of the brainstem in young SH rats, but it was normal in adult hypertensive animals. These results implicate adrenergic neurons in the brainstem and noradrenergic neurons in the hypothalamus in the development of spontaneous (genetic) hypertension in rats.
 ...
PMID:Changes in central catecholaminergic neurons in the spontaneously (genetic) hypertensive rat. 63 Jun 70

The potential role of adrenaline, both circulating and in the central nervous system, in the maintenance of high blood pressure was examined in stroke-prone spontaneously hypertensive rats (SHRSP). alpha-Monofluoromethyldopa, a long-lasting inhibitor of dopa decarboxylase, was used to induce rapid depletion of central and peripheral catecholamine stores. Subsequent inhibition of phenylethanolamine-N-methyltransferase (PNMT) allowed the gradual restoration of dopamine and noradrenaline but not adrenaline, resulting in a greater relative depletion of adrenaline. Adrenaline was almost totally depleted in the circulation and peripheral tissues. The resting level of blood pressure, however, was unaffected, excepting after administration of a vasopressin (AVP) antagonist. Moreover, there was no reduction in the magnitude of acute pressor responses to electrical stimulation of the rostral ventrolateral medulla oblongata (C1 area), despite extensive loss of adrenaline from the brainstem and spinal cord. The results suggest that adrenaline contributes to the resting level of blood pressure but that its loss can be offset by the pressor activity of AVP. Thus neither central nor peripheral adrenaline stores appear to be essential for the maintenance of hypertension or for centrally-evoked vasoconstriction in adult SHRSP.
 ...
PMID:Effects of depleting central and peripheral adrenaline stores on blood pressure in stroke-prone spontaneously hypertensive rats. 194 21

Previous studies have focused on the role of the central nucleus of the amygdala (CeA) in cardiovascular and other amygdaloid functions. The combined retrograde tracing/immunohistochemical method was used to test for the presence of enkephalin, neurotensin, neuropeptide Y, and catecholamine neurons within the nucleus of the solitary tract that send efferents to the CeA. After injections of retrograde tracer into the CeA, retrogradely labeled neurons were observed within the caudal, medial nucleus of the solitary tract. Most CeA-projecting neurons were located ipsilaterally within the medial nucleus of the solitary tract at the level of the area postrema. Retrogradely labeled enkephalin- and neurotensin-immunoreactive neurons were found within the medial nucleus of the solitary tract at this level, while retrogradely labeled neuropeptide Y-immunoreactive neurons were found within the medial nucleus of the solitary tract rostral to the area postrema. About 60-74% of CeA-projecting cells were also immunoreactive for tyrosine hydroxylase. Approximately 9% of retrogradely neurons were phenylethanolamine-N-methyltransferase immunoreactive. The results provide evidence that within the nucleus of the solitary tract, peptidergic CeA-projecting neurons have a topographic distribution. In addition, noradrenergic neurons within the A2 group, rather than adrenergic neurons of the C2 group, provide the bulk of catecholaminergic input to the CeA from the nucleus of the solitary tract. Cell counts indicate that each of these peptides may be colocalized (to varying extents) within catecholamine-producing neurons. Also the catecholaminergic and enkephalinergic contribution to the ascending pathway from the nucleus of the solitary tract to the CeA distinguishes it neurochemically from the descending pathway. Thus, although there are afferent and efferent connections between the nucleus of the solitary tract and CeA, their peptidergic/neurotransmitter connections are not necessarily reciprocal. Input from nucleus of the solitary tract peptidergic and catecholaminergic neurons to the CeA may be important in the etiology of a number of pathophysiological conditions including hypertension, gastric ulcers, and schizophrenia.
 ...
PMID:Organization of peptidergic and catecholaminergic efferents from the nucleus of the solitary tract to the rat amygdala. 198 Nov 74

In experimental hypertension, phenylethanolamine-N-methyltransferase (PNMT) activity and adrenaline levels are elevated in brainstem centers involved in cardiovascular regulation. Known PNMT inhibitors used to lower blood pressure have invariably shown alpha adrenergic activity as a side effect. A search for new inhibitors disclosed that CGS 19281A (4,9-dihydro-7-methoxy-3H-pyrido[3,4b]indole) inhibits PNMT (IC50, 2.7 x 10(-6) M) without interacting with the alpha-1 or alpha-2 adrenergic receptors. CGS 19281A (20 mg/kg i.v.) reduced PNMT activity (60% decrease; P less than 0.001) and adrenaline concentration (38%; P less than .025) in the brainstem of normal rats. In conscious deoxycorticosterone acetate-salt rats and spontaneously hypertensive rats, CGS 19281A (20 mg/kg i.v.) decreased blood pressure (50 mm Hg; P less than .001) and heart rate (26-36%; P less than .001) for 3 hr. Elevated brainstem adrenaline levels in deoxycorticosterone acetate-salt rats were decreased by CGS 19281A (42%; P less than .005) whereas i.c.v. administration of CGS 19281A (845 nmol/rat) to conscious spontaneously hypertensive rats decreased blood pressure (20 mm Hg; P less than .010) and heart rate (84 beats/min; P less than .001) as well. Therefore, CGS 19281A may be useful for the study of the function of PNMT and adrenaline in the central nervous system.
 ...
PMID:Antihypertensive effects of CGS 19281A, an inhibitor of phenylethanolamine-N-methyltransferase. 215 96

Levels of triiodothyronine, thyroxine, insulin, glucose and free fatty acids in the blood; contents of adrenaline, noradrenaline in adrenals and glycogen in the liver; activity of phenylethanolamine-N-methyltransferase in adrenals, hexokinase and glucose-6-phosphatase in the liver were studied in male Wistar rats and rats with inherited stress-induced arterial hypertension /ISIAH/. It was found that genetically caused rise of hypophyseal-thyroid systems activity in ISIAH-rats leads to a decrease of insulin blood level, activation of lipolysis and breach of glucose tolerance.
 ...
PMID:[Endocrine-metabolic relations in rats with genetic arterial hypertension]. 216 74

Catechol and indole metabolism in rostral ventrolateral medulla (RVLM or C1) was studied in response to changes in blood pressure across different rat strains. Sprague-Dawley, Wistar Kyoto normotensive and spontaneously hypertensive rats were anesthetized with urethane and had a 250 mu carbon paste in vivo electrochemical electrode implanted in RVLM area. Two electrochemical peaks were detected in this region. The first was at 0.12 V and the second at 0.28 V. To identify the electrochemical peaks, inhibitors of monoamine metabolism were administrated. alpha-Methylparatyrosine (tyrosine hydroxylase inhibitor), fusaric acid (dopamine-beta-hydroxylase inhibitor), pargyline (monoamine oxidase inhibitor) and LY 134046 (phenylethanolamine-N-methyltransferase inhibitor) showed that the first peak measured in the RVLM is likely to have multiple components including epinephrine, norepinephrine and 3,4-dihydroxyphenylacetic acid. The second peak most likely represents 5-hydroxyindole acetic acid. Phenylephrine or nitroprusside was infused to increase or decrease the blood pressure. Phenylephrine-induced hypertension reduced the catechol peak and increased the indole peak. By contrast, nitroprusside-induced hypotension produced reciprocal results. Hypotension led to an increase in the catechol peak and a reduction in the indole peak. The same pattern was observed in all three rat strains. We conclude that catechol and serotonin metabolism in RVLM changes in close relation to changes in blood pressure.
 ...
PMID:Catechol and indole metabolism in rostral ventrolateral medulla change synchronously with changing blood pressure. 272 47


1 2 3 4 5 Next >>