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

The chronic administration of high doses of guanethidine to rats produces complete destruction of the peripheral sympathetic nervous system. In a study of the effect of guanethidine-induced sympathectomy on the development of hypertension is spontaneous hypertensive rats (SHR, Okomoto strain), only a partial sympathectomy could be produced as assessed by biochemical parameters (tyrosine hydroxylase activity in ganglia and tissue norepinephrine concentrations) and by evaluation of response to stimulation of vasomotor outflow in pithed rat preparations. Other strains of rats (Sprague-Dawley, American Wistar, Kyoto Wistar) were uniformly sensitive to guanethidine sympathectomy. The resistance to guanethidine was not due to a lower accumulation of guanethidine in the neurons of SHR. Addition to the guanethidine treatment of low doses of antibody to nerve growth factor (NGF), which itself produced only a modest sympathectomy, resulted in an almost complete sympathectomy. SHR did not become hypertensive when sympathectomized by combined guanethidine-anti NGF. These results show that the sympathetic neurons of SHR differ from those of other strains with respect to sensitivity to guanethidine cytotoxicity and suggest the possibility of a role for NGF in that altered responsiveness.
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PMID:Unique resistance to guanethidine-induced chemical sympathectomy of spontaneously hypertensive rats: a resistance overcome by treatment with antibody to nerve growth factor. 3 37

Daily intraperitoneal injection of cadmium chloride (1 mg/kg) for 45 days significantly increased adrenal weights and augmented the levels of adrenal norepinephrine and epinephrine as well as the activity of adrenal tyrosine hydroxylase. Discontinuation of the heavy metal treatment for 28 days, in rats previously injected with cadmium for 45 days, restored the activity of tyrosine hydroxylase as well as the amount of norepinephrine and epinephrine. In contrast, adrenal weights were restored only partially following the withdrawal of cadmium treatment. Evidence indicates that the changes in adrenal catecholamine metabolism may be the result of stress induced by chronic exposure to this heavy metal. In addition, some of the untoward effects such as hyperglycemia and arterial hypertension seen during cadmium toxicity might be related to increased synthesis of epinephrine in adrenal glands.
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PMID:Effect of chronic cadmium treatment on rat adrenal catecholamines. 23 28

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.
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PMID:Dihydralazine and catecholamine-synthesizing enzymes in spontaneous hypertension. 49 52

Prevention of high blood pressure in uninephrectomized, DOCA-saline treated rats was observed after treatment with central tyramine precursors. We suggest that the high blood pressure is either due to relative lack of tyrosine, which might be caused by the hyperactivity of tyrosine hydroxylase, or to hypoactivity of the decarboxylase: in both cases the result is diminished tyramine synthesis.
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PMID:Central tyramine prevents hypertension in uninephrectomized DOCA-saline treated rats. 92 98

The noradrenaline (NA) metabolism rate was studied in discrete brain areas of young rats with inherited stress-induced arterial hypertension (ISIAH rats) in the period of rapid hypertension formation (4th week, 22nd-23rd days of life). The rate of metabolism was evaluated according to the NA concentration regression lines after inhibition of tyrosine hydroxylase oridopamine-beta-hydroxylase. The level of NA and the rate of its metabolism in the posterior hypothalamus, midbrain, and pons were higher in ISIAH rats than in normotensive Wistar rats. These parameters in the frontal cortex, anterior hypothalamus, and medulla oblongata were the same in the two rat strains. The possible role of NA metabolic changes in the development of inherited arterial hypertension is discussed.
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PMID:[Noradrenaline metabolism in the brain of young rats during formation of inherited stress-induced arterial hypertension]. 130 23

Immunohistochemical distributions of tyrosine hydroxylase and calmodulin in the rat forebrain were analyzed quantitatively as a possible model for the hypertension mechanism. The brain slices of spontaneously hypertensive rats (SHR) at 12 weeks of age were stained immunohistochemically for tyrosine hydroxylase and for calmodulin, and the distributions and amounts of these proteins were measured at 40-microns intervals by a fluorescence microphotometry system in comparison with those in normotensive control, Wistar Kyoto rats (WKY, the parent strain of SHR). Tyrosine hydroxylase levels in the neostriatum, nucleus accumbens, nucleus septi lateralis and tractus diagonalis, and calmodulin levels in the medial part of the neostriatum of SHR were lower than those in WKY. We reported previously that the decrease of the serum calcium level in SHR causes a decrease of the dopamine levels in the neostriatum and nucleus accumbens regions through a calmodulin-dependent system, and subsequent low levels of dopamine in the brain which may produce an increase in blood pressure. Combining this finding and our previous reports, we also suggest that the lower dopamine levels seen in the neostriatum and nucleus accumbens regions of SHR may result from the decrease in tyrosine hydroxylase and/or calmodulin levels in these regions in addition to the abnormality of calcium metabolism, and low levels of dopamine may produce an increase in blood pressure through functions of cerebral dopaminergic neurons and peripheral sympathetic nerves.
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PMID:Quantitative immunohistochemical distributions of tyrosine hydroxylase and calmodulin in the brains of spontaneously hypertensive rats. 136 39

An 8-year-old boy developed severe systemic hypertension during resection of an intramedullary tumor. The histological, ultrastructural and immunocytochemical characteristics of the tumor are those of a gangliocytoma. Based on the demonstration of tyrosine hydroxylase in neuronal tumor cells, it is postulated that catecholamine secretion was responsible for the systemic hypertension.
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PMID:Intramedullary secretory gangliocytoma. 176 34

Rats on calcium-deficient diets developed hypocalcemia, hyperparathyroidism and hypertension and showed an increase in plasma catecholamines. Adrenal gland catecholamines were decreased while tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) were found to be increased, as compared to controls. In contrast, no significant differences were found between controls and parathyroidectomized rats in plasma catecholamines, and catecholamines, TH and DBH of the adrenal gland. These findings seem to indicate that the genesis of hypertension in rats on a low calcium diet is secondary to hyperparathyroidism caused by a low calcium diet. Furthermore, some relation between catecholamines and parathyroid hormone seems to exist in the regulation of blood pressure in rats.
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PMID:Dietary calcium deprivation increased the levels of plasma catecholamines and catecholamine-synthesizing enzymes of adrenal glands in rats. 196 34

Despite recommended preoperative preparation with alpha-adrenergic blockers, severe hemodynamic instability may occur during operations to resect pheochromocytoma. We combined the alpha-blocker phenoxybenzamine with the tyrosine hydroxylase inhibitor metyrosine in an attempt to better manage the hypertension of patients with pheochromocytoma undergoing surgical resection. This report reviews the cases of 25 consecutive patients undergoing surgery for known intra-abdominal pheochromocytoma. Each patient had elevated serum or urine levels of catecholamines or their metabolites. Nineteen patients were prepared before operation with phenoxybenzamine and metyrosine and six patients were given phenoxybenzamine alone. There were no significant differences in maximum, minimum, or mean blood pressure before or after tumor resection between patients who received metyrosine and those who did not. However careful review suggested that those who received metyrosine had more severe disease as judged by biochemical criteria. Study of selected patients matched for age and severity of disease suggested that the intraoperative blood pressure management of patients prepared with phenoxybenzamine and metyrosine was facilitated. In addition metyrosine-prepared patients lost less blood and required less volume replacement during surgery than did non-metyrosine-prepared patients. There were no apparent differences in postoperative fluid requirements. Although the study is not a prospective randomized trial, a retrospective review of patients managed with the combination of phenoxybenzamine and metyrosine suggests that surgery to resect pheochromocytoma can be better performed with both drugs than with phenoxybenzamine alone. The combination regimen appears to result in better blood pressure control, less blood loss, and the need for less intraoperative fluid replacement than does the traditional method of single-agent alpha-adrenergic blockade.
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PMID:Surgical management of pheochromocytoma with the use of metyrosine. 197 40

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.
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PMID:Organization of peptidergic and catecholaminergic efferents from the nucleus of the solitary tract to the rat amygdala. 198 Nov 74


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