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

1. Activity of peripheral and central catecholaminergic neurons was studied in spontaneously hypertensive rats (SHR) and deoxycorticosterone (DOCA)-salt hypertensive rats. 2. In young SHR (4 weeks) the plasma values of bpth noradrenaline and dopamine-beta-hydroxylase activity were increased compared with those of normotensive rats of the Wistar/Kyoto strain. Total catecholamines (mostly adrenaline) were not significantly different. 3. In the adrenal glands of 2-weeks-old and 4-weeks-old SHR activities of tyrosine hydroxylase, dopamine-beta-hydroxylase, phenylethanolamine-N-methyl transferase were decreased, compared to Wistar/Kyoto rats. 4. The adrenaline-forming enzyme was elevated in the A1 and A2 regions of the brain stem of 4-weeks-old SHR and in the A1 region of adult DOCA-salt hypertensive rats. 5. In the adrenal glands of adult DOCA-salt hypertensive rats tyrosine hydroxylase activity was increased. 6. These results implicate peripheral noradrenaline-containing neurons and central adrenaline-containing neurons in the development of genetic and experimental hypertension in rats.
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PMID:Peripheral and central catecholaminergic neurons in genetic and experimental hypertension in rats. 1 56

The activities of monoamine biosynthetic enzymes were measured in brain regions of several hypertensive rat models at various ages. The types of hypertensive rats were the spontaneously hypertensive rat (SHR) and a stroke-prone substrain of the SHR as well as DOCA-salt and renal hypertensive rats. The genetically hypertensive rats had significantly elevated blood pressures as compared to the Wistar-Kyoto control rat after 5 weeks of age. During the early development of hypertension in the SHR, the activities of tyrosine hydroxylase in the hypothalamus and corpus striatum and of dopamine-beta-hydroxylase in the hypothalamus and pons-medulla were significantly higher than in the control rats. Tryptophan-hydroxylase was also elevated in the hypothalamus in SHR. From 3 to 8 weeks of age there appeared to be a significant correlation between hypothalamic dopamine-beta-hydroxylase activity and blood pressure in the hypertensive rats. In contrast, the activities of tyrosine hydroxylase and dopamine-beta-hydroxylase were slightly decreased in the DOCA-salt and renal hypertensive rats. It is suggested that noradrenergic or adrenergic neurons in the hypothalamus may participate in the initiation of elevated blood pressure in the genetic, but not in the DOCA-salt or renal hypertensive rats.
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PMID:Regional changes in the activities of aminergic biosynthetic enzymes in the brains of hypertensive rats. 1 54

The effects of acebutolol, a cardioselective beta-adrenoceptor blocking agent, on the systolic blood pressure and heart rate were investigated in conscious Kyoto Wistar normotensive rats (WKY), spontaneously hypertensive rats (SHR) and DOCA-NaCl hypertensive rats (DOCA rats) and the results compared with those of propranolol and practolol. In WKY and DOCA rats, the intraperitoneal administration of acebutolol, propranolol and practolol (0.5 approximately 20 mg/kg) produced a hypotensive action, however, these effects were observed only with restricted doses and there was no evidence of a dose-dependency. The heart rate was decreased by acebutolol and propranolol, but was increased by practolol which possesses an intrinsic sympathomimetic activity. In SHR, propranolol produced a dual action, a slight rise followed by a slight fall, the change not being significant, while practolol induced a slight hypertension. On the other hand, acebutolol in high doses induced a dose-dependent hypotensive action. The heart rate was markedly and dose-dependently decreased by these three agents. Thus, while propranolol and practolol produced hypotensive effects in WKY and DOCA rats, acebutolol produced hypotensive effects in WKY, SHR and DOCA rats. These results suggest that acebutolol is a beta-adrenoceptor blocking agent which possesses hypotensive activity in hypertensive rats.
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PMID:[Effect of acebutolol, a cardioselective beta-adrenoceptor blocking agent, on the blood pressure in rats (author's transl)]. 4 60

Swimming, if undertaken for 1 hr/day, 3 days/week for 6 weeks prior to treatment with DOCA, unilateral nephrectomy, and salt-loading, delayed the development of hypertension in rats. If the swimming were undertaken concurrently with or after initiation of treatment with the above hypertensive regime, then it was without effect on the level of blood pressure attained or the length of time required to attain a given blood pressure. Swimming in itself resulted in a significant increase in arterial blood pressure. Previous training, such as swimming, may delay the development of hypertension through an alteration in vascular structure or smooth muscle sensitivity. The increase in blood pressure noted in physically trained rats may be a consequence of the training regime itself acting as a stressor.
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PMID:Relationships between physical training and DOCA hypertension in rats. 13 Jun 37

Young and adult uninephrectomized male rats (aged 25 and 87 days respectively) were exposed to an increased salt intake (1% saline as the only drinking fluid) either alone or in combination with DOCA-treatment for 25 and 46 days respectively. Age dependent differences of interrelationships between saline intake (SI), blood pressure (BP) and kidney weight (KW) were studied during development of salt and DOCA-salt hypertension to specify possible factors involved in the higher susceptibility of the young rats to these regimes. Correlation analysis was employed using the step-wise regression procedure. Only in the young rats did saline treatment induce an increase in KW, which preceded the development of mild hypertension. This age group also responded to DOCA-saline treatment with a more pronounced increase in both BP and KW. SI was higher in the young than adult rats exposed to either saline or DOCA-saline treatment. This, however, does not account by itself for the higher hypertensive response of the young rats, since there was no primary relationship between SI and BP in the hypertensive groups. Increase in KW accompanying development of hypertension was dependent on BP in the young rats and on SI in adult rats. This indicates that saline and DOCA-saline treatment renders the kidneys of young rats more sensitive to damaging effects of BP, which play a part in the more pronounced hypertensive response.
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PMID:Age differences in interrelationships between saline consumption, blood pressure and kidney weight in salt hypertension in the rat. 14 81

Young, unilaterally nephrectomized, female Sprague-Dawley rats were given daily sc injections of 19-nor-deoxycorticosterone acetate (19-nor-DOCA) in oil at a dosage of 100 micrograms/day for 21 days and twice that amount for a further 11 days. One group drank distilled water and another drank 1% NaCl solution. Comparable control groups received oil injections. Another group received DOCA at the same steroid dosage and drank saline. Both 19-nor-DOCA-treated groups rapidly became hypertensive and developed cardiac hypertrophy, as did those given DOCA and saline. Saline consumption was greater in rats receiving 19-nor-DOCA, than in those given DOCA. Rats injected with 19-nor-DOCA and given water to drink showed enhanced growth and developed thymus enlargement and displayed hypokalemia and a reduction in both serum renin activity and corticosterone concentration. Plasma sodium concentration was not affected by any form of treatment. Clearly, 19-nor-DOCA is a potent mineralocorticoid and hypertensogenic agent. Since the parent steroid is known to be present abundantly in the urine of rats with regenerating adrenal glands, although circulating amounts have not yet been ascertained in that circumstance, it may be etiologically involved in adrenal regeneration hypertension, which such rats are prone to develop.
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PMID:Influence of 19-nor-deoxycorticosterone on blood pressure, saline consumption, and serum electrolytes, corticosterone, and renin activity. 15 70

1 Prolonged infusion (11 h) of both saralasin and angiotensin-converting enzyme inhibitor (SQ20881) gradually lowered BP in two-kidney hypertensive rats to levels similar to that in normotensive rats infused with dextrose. 2 Saralasin did not lower BP in DOCA-salt hypertensive rats. 3 These observations support the notion that in chronic renal hypertension, angiotensin II may maintain hypertension by a slowly developing action. 4 Plasma angiotensin II in rats infused with SQ20881 was suppressed relative to renin, but was not eliminated. 5 Chromatography of angiotensin II extracts from dogs infused with converting enzyme inhibitor (SQ14,225) showed that the very high levels of angiotensin I achieved after treatment with SQ14,225 can lead to falsely high estimated angiotensin II levels as a result of angiotensin I cross-reacting with the angiotensin II assay.
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PMID:Inhibitors of the renin-angiotensin system in experimental hypertension, with a note on the measurement of angiotensin I, II and III during infusion of converting-enzyme inhibitor. 22 15

The development of experimental deoxycorticosterone-salt (DOCA-salt) and renal artery clip hypertension in rats is associated with alterations in the sensitivity of the myocardium to adrenergic stimulation. We studied beta-adrenergic receptors and isoproterenol-stimulated adenylate cyclase in myocardial membranes from hypertensive rats to determine whether this altered sensitivity is associated with any change in beta-adrenergic receptors. The specific binding of the beta-adrenergic antagonist, 125I-iodohydroxybenzylpindolol, was used to measure numbers and affinities of receptors in myocardial membrane preparations. Cardiac membranes from both DOCA-salt and renal hypertensive rats showed significantly fewer beta-receptors than did membranes from control, normotensive rats. Receptor affinity remained unchanged. This decrease was from 110 +/- 19 to 49 +/- 5 fmol/mg protein for DOCA-salt hypertension and from 110 +/- 18 to 75 +/- 16 fmol/mg protein for renal artery clip hypertension. Isoproterenol-stimulated adenylate cyclase activity also was lower in membranes from hypertensive rats, whereas basal and fluoride-stimulated activities were unchanged.
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PMID:Decreased cardiac beta-adrenergic receptors in deoxycorticosterone-salt and renal hypertensive rats. 22 57

High calcium diet induces an hypertension lasting one week in normal rats. In mineralocorticoid treated rats (DOCA + NaCl), the same diet prevents for 10 weeks the increase of arterial blood pressure. Parathyroid activity (estimated by urinary cAMP) is decreased after the high calcium diet. These results confirm the role of the parathyroid glands in mineralocorticoid hypertension in the rat.
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PMID:[Arterial blood pressure and high calcium diet in normal and mineralcorticoid (DOCA and sodium chloride hypertensive rats]. 22 48

1. The concentration of catecholamines was measured in several brain areas of the Hewbrew University Sabra rat (SB rat), and in two substrains selected for their respective sensitivity (H) or immunity (N) to hypertension. 2. Hypertension was induced in SB rats by DOCA-salt, renal artery constriction and NaCl 1.7% drinking. The noradrenaline content was consistently elevated in the medulla oblongata of hypertension animals. In other brain areas the rise in noradrenaline varied in the different types of hypertension. 3. Administration of DOCA-salt to H and N rats, while causing marked hypertension in the former, had no effect on noradrenaline in either strain. 4. Untreated, normotensive N rats had in the medulla oblongata, significantly higher concentrations of noradrenaline than did H rats. 5. Differences in brain noradrenaline may explain the inherited susceptibility or resistance to hypertension in H and N rats.
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PMID:Hypertension and brain catecholamine distribution in the Hebrew University Sabra, H and N rats. 28 36


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