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

Chronic elimination of renal sympathetic nerve activity will prevent one-third of the hypertension in spontaneously hypertensive rats (SHR), and manipulations of the immune system will block one-half of the spontaneous hypertension. In the present study the combined role of enhanced sympathetic activity and immunological dysfunction in the pathogenesis of hypertension in the SHR was investigated. Neonatal SHR received thymic implants from donor Wistar rats. When these thymus-implanted SHR were 6 weeks old they underwent bilateral renal denervation. The renal denervation procedure was repeated when the SHR were 9, 12, 15 and 18 weeks old. When the implanted, denervated SHR were 20 weeks old their average systolic pressure (SP) was 146 +/- 4.0 mmHg (mean +/- s.e.m.). The SP of age-matched, sham-operated Wistar-Kyoto (WKY) rats was 127 +/- 2.2 mmHg, while it averaged 196 +/- 4.4 mmHg in 20-week-old sham-operated SHR. Therefore, neonatal thymic implants in combination with chronic renal denervation abolish three-quarters of the hypertension in the SHR. These results support the hypothesis that immunological dysfunction and enhanced sympathetic activity cause spontaneous hypertension.
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PMID:Immunological dysfunction and enhanced sympathetic activity contribute to the pathogenesis of spontaneous hypertension. 346 8

We studied the effect of thymectomy on the development of hypertension in spontaneously hypertensive rats (SHR). There were no significant differences between thymectomized and sham thymectomized SHR during either the initial or chronic phase of spontaneous hypertension. Similarly, administration of anti-Thyl. 1 or anti-T sera did not influence the blood pressure in SHR during the chronic phase. The results suggest that the thymus does not play a direct role in the development and maintenance of blood pressure in SHR.
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PMID:The effect of thymectomy on the development of hypertension in spontaneously hypertensive rats. 393 45

The hypertensogenic effect of 18-oxocortisol, an aldosterone analogue possessing both mineralocorticoid and glucocorticoid properties, was studied at the same dosage but under different experimental conditions in two experiments. Under experimental conditions conducive to the development of mineralocorticoid hypertension (i.e., rats with a single kidney on a high NaCl intake), there was an extremely rapid onset of saline polydipsia and hypertension accompanied by cardiac and renal enlargement, marked thymic involution without adrenal atrophy, cardiovascular lesions, and hypokalemia. With the exception of the thymic changes, the same changes occurred in rats given the biologically equivalent dose of deoxycorticosterone acetate. Under circumstances favoring the development of glucocorticoid hypertension (i.e., intact rats on a normal sodium intake), the same dose had only a transient blood pressure-elevating effect, attaining prehypertensive levels at most, and caused neither chronic hypertension nor hypokalemia. The biologically equivalent glucocorticoid dosage of cortisol was similarly ineffective. Under these circumstances, both steroids caused thymus involution but only 18-oxocortisol caused kidney enlargement.
Hypertension 1986 Apr
PMID:Hypertensive potency of 18-oxocortisol in the rat. 395 17

Administration of 10 mg of methylandrostenediol for 10 weeks to uninephrectomized, salt drinking, female Sprague Dawley rats caused severe hypertension with extensive renal and cardiovascular damage. The hypertension was accompanied by increased consumption of sodium, high sodium levels in peripheral plasma, decreased weight of the pituitary, thymus, adrenals and ovaries and decreased content of renal renin. Methylandrostenediol treatment also produced impairment of normal adrenal steroidogenesis, reflected in elevated production in vitro of 11-deoxycorticosterone during incubation of adrenal gland homogenates with (14)C-progesterone. Such increased production of deoxycorticosterone is probably responsible for the development of the hypertensive disease. If the methylandrostenediol-treated animals were kept alive for 12 additional weeks after suspension of the treatment with the androgen, the hypertension, as well as the high sodium consumption, high plasma sodium concentrations and low levels of renal renin, persisted to the end of the experiment. The cardiovascular and renal lesions in these animals, killed 12 weeks after suspension of the androgen administration, were similar to those seen in the rats receiving methylandrostenediol but killed at the tenth week of the treatment. Suspension of methylandrostenediol administration, however, resulted in a return to normal weight of the pituitary, thymus, adrenals and ovaries within 12 weeks. Normal amounts of deoxycorticosterone were formed in vitro by the adrenal glands of these rats and the return to normal structure was also confirmed by a electron microscopic study. Thus, contrary to a previous experiment where methylandrostenediol was given for a shorter period of time and the hypertension was reversible, it was shown in this study that metacorticoid hypertension is induced by methylandrostenediol administration, as it is with treatment with deoxycorticosterone. Since adrenal steroidogenesis returned to normal, some other mechanisms must be involved in maintaining the hypertension. It is very likely that these factors are consequent to the extensive and irreversible renal and cardiovascular damage.
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PMID:Irreversibility of methylandrostenediol-induced hypertension in the rat after suspension of the androgen treatment. 508 Jul 4

Spontaneously hypertensive rats (SHR) that develop hypertension and arterial lesions resembling human periarteritis nodosa were found to possess a selective depression of T cell functions with an appearance of natural thymocytotoxic autoantibody (NTA). The relationship between T cell depression and hypertension in these animals was investigated. The immune responsiveness of T cell-depressed SHR was completely recovered by histocompatible thymus grafts and was partially restored by histoincompatible allogeneic or xenogeneic thymus grafts or by injection of thymus extracts. Transplantation of compatible thymus tissues into neonatal SHR produced long-lasting recovery of immune functions. When complete immunologic restoration was achieved, significant suppression of high blood pressure was obtained. The SHR that showed high blood pressure were always accompanied with high NTA titers and arterial lesions. Thymus grafts or thymus extracts significantly decreased the titers of NTA. The development and dissemination of arterial lesions, which may cause increased blood flow resistance, were completely prevented by compatible thymus grafts into neonatal SHR. These results suggest that thymus grafts and thymus extracts may suppress the development of hypertension by preventing or curing the periarteritis nodosa in SHR.
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PMID:Restoration of T cell depression and suppression of blood pressure in spontaneously hypertensive rats (SHR) by thymus grafts or thymus extracts. 612 Jan 94

Male and female, young (2 months old) and mature (10 months old), obese and nonobese, spontaneously hypertensive rats (SHR) were treated with dexamethasone, 5 micrograms/rat and 10 micrograms/rat, respectively, subcutaneously (SC) 2 times daily for 5 months. Steroid treatment stilled the voracious appetite of the obese SHR, and the massively obese, mature animals were reduced to almost normal size. The young, steroid-treated, obese SHR did not develop their genetically programmed corpulency. The untreated, young and mature, obese SHR ate voraciously, became massively obese, and developed their characteristic Cushing's disease-like spectrum of degenerative changes, eg, hypertension, hyperlipidemia, hyperglycemia, muscle wasting, kidney stones, thin skin, and accelerated aging. The blood pressure of the steroid-treated animals was lowered concomitant with reduced levels of circulating ACTH, beta endorphin, insulin, triglycerides, and cholesterol. Dexamethasone caused hyperlipidemia, hyperglycemia, and increased BUN levels in young obese and nonobese SHR only. The mature obese SHR had giant-sized thymus glands that were further enlarged with steroid treatment; dexamethasone was thymolytic in young, obese and nonobese SHR. Dexamethasone caused severe reduction of pituitary and adrenal gland size, simulating the condition of hypophysectomy. These findings demonstrate that dexamethasone suppression of the pituitary-adrenal axis palliates and prevents the spontaneous development of Cushingoid degenerative changes in these genetically obese and hypertensive rats.
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PMID:Dexamethasone suppression of cushingoid degenerative changes in obese spontaneously hypertensive rats (SHR). 631 58

Spontaneously hypertensive male and female rats (SHR) were compared with Wistar/Kyoto (W/K) controls at 15 wk and 80 wk of age. Treatment of the young and old hypertensives with thymosin, fraction 5, lowered the blood pressure within 4 wk of the start of treatment. Following 10 wk of injections, the blood pressures of the hypertensive rats remained at a depressed level for about 6 wk. The thymic hormone raised the depressed spontaneous T-cell rosette formation of the aged hypertensive rat and increased the lymph node T-cell response to the mitogens, Con A and PHA. Thymosin administration over a period of 7 wk increased the size of the aged hypertensive thymus. No similar effect was observed in the W/K. Spleen cell production of prostaglandin E (PgE) was markedly higher in the young hypertensive and immune complex deposition was found in the glomeruli and tubules of the aged SHR kidneys. Thymosin lowered the high level of PgE to normal and decreased the immune complex deposition in the kidney. IgG1 levels were considerably depressed in the SHR as compared to the W/K. Following thymosin administration levels of IgG1 increased 2-fold in both rat strains. Plaque-forming cells from the spleens of the untreated SHR were about 3-fold less than those of the age-matched W/K. Following treatment with thymosin the number of plaque-forming cells of both groups demonstrated a substantial further decrease. Spontaneous hypertension in rats is similar, in certain respects to autoimmune-like diseases in humans with a depression in T-cell activity as well as immune complex deposition; both conditions being altered by exposure to a thymic extract.
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PMID:Immune response modulation in the spontaneously hypertensive rat. 634 14

Infarct-kidney hypertension was induced in congenital athymic nude rats, and in their immunologically normal haired littermates. In both groups a significant initial increase in blood pressure was seen in the course of the first 30 days. In the remainder of the observation period of 120 days the mean blood pressure in the nude rats decreased to a significantly lower level where-as in the haired rats the mean blood pressure remained unchanged at the high level. Although a high mortality weakened the results, it is hypothesized that the failing ability to maintain the elevated blood pressure into the late phase in the nude rats could be due to impaired thymus function. Nine of 14 haired rats had increased numbers of lymphocytes around intrarenal arteries, in contrast to only 1 of 10 nude rats. A periarteritis nodosa like picture was observed around mesenterial arteries of 3 nude and 2 haired rats. The level of plasma renin was similar preoperatively in nude and haired rats. Infarction of the kidney was followed by a significant decrease in the plasma renin level in both nude and haired rats, which at 10 days was significantly lower in haired than in nude rats, despite a higher blood pressure in the latter.
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PMID:Infarct-kidney hypertension in the rat mutant nude. 636 29

Infarct kidney hypertension was induced in congenital athymic nude rats and in their haired normal littermates. In both groups a significant and similar elevation of blood pressure was observed. The mesenteric vessels were studied histologically five, 12 and 20 days after operation. Necrotizing vasculitis with and without perivascular inflammatory reactions was found in mesenteric arteries and arterioles in six out of six athymic and in six out of 11 control rats. In sham operated athymic rats and in haired littermates neither hypertension nor vasculitis was observed. These observations indicate that the thymus play no role in the pathogenesis of acute hypertensive vascular disease.
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PMID:Necrotizing vasculitis in athymic rats with infarct kidney hypertension. 668 Oct 44

A 39-year-old man with an ACTH producing oncocytic carcinoid of the thymus is reported here. His symptoms were pigmentation, facial and pretibial edema, and high blood pressure. Endocrinological examination revealed the ectopic ACTH syndrome and, especially, high content in the intrathoracic venous blood. On histological examination, the tumor was found to be composed of uniform eosinophilic cells, with no argentaffin granules being demonstrated. Ultrastructural findings revealed a large number of mitochondria and numerous distinct electron-dense neurosecretory granules in the cytoplasm. Abnormally high levels of ACTH, beta-endorphin and gamma-MSH were also found in this tumor tissue. By total extirpation of the tumor, clinical symptoms and laboratory data were entirely normalized.
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PMID:An ectopic, ACTH producing, oncocytic carcinoid tumor of the thymus: report of a case. 674 52


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