UMLS:C0020538 - FACTA Search

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

We examined a young man who had a benign giant cell granuloma of the maxilla, which we subsequently diagnosed as a brown tumor associated with hyperparathyroidism. During surgery for the granuloma, the patient developed severe hypertension and was discovered to have an extra-adrenal pheochromocytoma. Oncogene and calcitonin testing for medullary carcinoma of the thyroid was negative. Therefore, despite the presence of both pheochromocytoma and hyperparathyroidism, we concluded that this patient did not have multiple endocrine neoplasia type 2a.
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PMID:Maxillary giant cell granuloma, pheochromocytoma, and hyperparathyroidism without medullary thyroid carcinoma. 1096 67

It is well-known that morphine is the king of analgesics. It is widely used, and administered in various ways for the control of acute and chronic pain states. There are, however, certain types of pain and certain clinical conditions in which morphine cannot be used due to the risk of possible complications. These are usually pain states associated with intracranial hypertension, the presence of serious respiratory problems, the onset of major opioid tolerance, persistent vomiting, and so on. The search for "alternative analgesics" has been in progress for a decade, alternatives that could be used alone or in combination for spinal administration in the treatment of complex chronic pain states and with a low incidence of secondary effects. Today, research is carefully assessing the clinical effectiveness and the side effects of a series of drugs for spinal administration, that is, epidural or intrathecal, such as the new narcotics, alpha-2 agonists, central muscle relaxants, calcitonin, and local anesthetics. In this alternative analgesic category we have to mention the somatotrophin-release inhibiting factor (SRIF), which is an ubiquitous native hormone with widespread, predominantly inhibitory actions, and octreotide, its synthetic analogue. In this article we review the literature on the natural drug and its synthetic analogue, paying particular attention to the problems connected with intraspinal administration and analgesic properties.
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PMID:The epidural and intrathecal administration of somatotrophin-release inhibiting factor: native and synthetic analogues. 1099 19

Long-term administration of a subpressor dose of angiotensin II (Ang II) leads to pressor hyperresponsiveness and slow development of hypertension. Our preliminary data show that mRNA expression for calcitonin-gene related peptide in dorsal root ganglia was significantly increased by subpressor infusion of Ang II. To determine the role of sensory nerves in the development of hypertension induced by subpressor infusion of Ang II, newborn Wistar rats were given 50 mg/kg SC capsaicin on the 1st and 2nd days of life. After the weaning period, male rats were divided into 4 groups and subjected to the following treatments for 2 weeks: capsaicin+Ang II (150 ng. kg(-1). min(-1) SC by osmotic pumps, CAP-AII), capsaicin+vehicle (CAP), control+Ang II (CON-AII), and control+vehicle (CON). The results show that mean arterial pressure was significantly elevated in both Ang II-infused rats compared with non-Ang II-treated rats (P<0.05), and it was higher in CAP-AII than in CON-AII rats (P<0.05). The 24-hour urinary and sodium excretions were lower in CAP-AII than in CON-AII, CAP, and CON rats (P<0.05). These data demonstrated that sensory denervation exacerbates the development of hypertension and impairs renal excretory function when a subpressor dose of Ang II is given. These results indicate that activation of sensory nerves, either by Ang II or by other hormonal or hemodynamic factors, plays a compensatory role in promoting urine and sodium excretion and attenuating elevated blood pressure initiated by Ang II.
Hypertension 2000 Oct
PMID:Development of hypertension induced by subpressor infusion of angiotensin II: role of sensory nerves. 1104 Feb 34

Adrenomedullin (ADM) is a vasodilator produced by vascular endothelium and smooth muscle cells. Although plasma ADM levels are increased in patients with hypertension, heart failure, and myocardial infarction, little information exists regarding the microvascular response to ADM in the human heart. In the present study we tested the hypothesis that ADM produces coronary arteriolar dilation in humans and examined the mechanism of this dilation. Human coronary arterioles were dissected and cannulated with micropipettes. Internal diameter was measured by video microscopy. In vessels constricted with ACh, the diameter response to cumulative doses of ADM (10(-12)-10(-7) M) was measured in the presence and absence of human ADM-(22-52), calcitonin gene-related peptide-(8-37), N(omega)-nitro-L-arginine methyl ester (L-NAME), indomethacin (Indo), (1)H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one, SQ-22536, or KCl (60 mM). ADM dilated human coronary arterioles through specific ADM receptors (maximum dilation = 69 +/- 11%). L-NAME or N-monomethyl-L-arginine attenuated dilation to ADM (for L-NAME, maximum dilation = 66 +/- 7 vs. 41 +/- 13%, P < 0.05). Thus the mechanism of ADM-induced dilation involves generation of nitric oxide. However, neither (1)H-[1,2,4]oxadiazolo-[4, 3-a]quinoxalin-1-one, SQ-22536, nor Indo alone altered dilation to ADM. High concentrations of KCl blocked dilation to ADM. The magnitude of ADM dilation was reduced in subjects with hypertension. We propose that, in human coronary arterioles, ADM elicits vasodilation in part through production of nitric oxide and in part through activation of K(+) channels, with little contribution from adenylyl cyclase. The former dilator mechanism is independent of the more traditional pathway involving activation of soluble guanylate cyclase.
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PMID:Human coronary arteriolar dilation to adrenomedullin: role of nitric oxide and K(+) channels. 1108 13

Calbindin-D28k is an intracellular protein with high affinity for calcium. In the kidney, this protein is exclusively localized in the distal tubule and in the proximal part of the collecting ducts. Functionally, calbindin-D28k is supposed to be involved in the regulation of the reabsorption of calcium and possibly magnesium in the distal nephron though the exact regulatory mechanisms are not yet known. Thus, several theories regarding the functional role of calbindin-D28k have been proposed: The carrier theory describes calbindin-D28k as a transport protein which binds calcium and then transports it from the luminal to the basolateralcell membrane. The buffer theory assumes that calbindin-D28k functions by binding calcium ions to prevent intracellular calcium concentrations from reaching toxic levels. The activator theory describes that calbindin-D28k increases the activity of calcium channels or the enzymatic activity of the Ca++-Mg++-ATPase in the luminal membrane and thereby increases the tubular reabsorption of calcium. The renal calbindin-D28k is dependent upon vitamin D. Pharmacological doses of the active vitamin D metabolite 1,25-(OH)2D increases the concentrations of renal calbindin-D28k, whereas the concentration of calbindin-D28k is low in conditions with reduced levels of circulating 1,25-(OH)2D. Likewise, plasma calcium concentrations, uremia and hypertension affect calbindin-D28k expression. However, several studies have rendered probable the effect of additional factors in the regulation of renal calbindin-D28k. The aim of the present dissertation therefore was to examine the regulation of renal calbindin-D28k in a series of physiological and pathophysiological conditions established in vivo in the rat. A possible correlation between hypertension and calbindin-D28k was examined in three models of experimental hypertension: the genetically defined spontaneous hypertensive rat, the salt-sensitive Dahl rat and the renovascular hypertensive rat. These three models clearly demonstrated three separate patterns in the calcium metabolism, but the studies were unable to support a role for calbindin-D28k in the development of hypertension. In all three models the development of hypertension caused an increased plasma 1,25-(OH)2D. This increase was accompanied by either unaltered or reduced levels of renal calbindin-D28k possibly secondary to a cellular resistance against 1,25-(OH)2D. Magnesium binds to calbindin-D28k with a relatively high affinity. The regulation of urinary magnesium excretion takes place in the distal tubule where calbindin-D28k is found in high concentrations. Therefore, a possible relation between magnesium and calbindin-D28k was examined. The studies demonstrated not previously known connections between magnesium intake, urinary magnesium excretion and renal calbindin-D28k which suggests that this protein is involved in the regulation of magnesium homeostasis by the kidney. Calcitonin increases the reabsorption of calcium in the distal tubule. Therefore, the effect ofcalcitonin on renal calbindin-D28k was examined both by eliminating the endogeneous calcitonin production by a selective thyroidectomy followed by an autotransplantation of the parathyroid glands and further by infusion of calcitonin. These studies demonstrated unchanged concentrations of renal calbindin-D28k. It was concluded that the increased calcium reabsorption induced by calcitonin in the distal tubule is not mediated by calbindin-D28k. Urinary calcium excretion is in part regulated by the action of PTH on calcium reabsorption in the distal nephron. Previous reports of increased expression of renal calbindin-D28k in uremic rats led us to suggest that secondary hyperparathyroidism associated with uremia induced the synthesis of renal calbindin-D28k. Therefore, the effect of PTH was examined in a study comprising selective parathyroidectomy and infusions of PTH, PTHrP, 1,25-(OH)2D and calcium. (ABSTRACT TRUNCATED)
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PMID:Regulation of renal calbindin-D28K. 1109 7

Spinal cord injury leads to many forms of autonomic dysfunction including autonomic dysreflexia, a condition involving recurrent episodes of paroxysmal hypertension and associated bradycardia. This hypertension may reach intensities that are life-threatening. We investigated autonomic dysreflexia and the sprouting of central processes of primary afferent neurons (a potential mechanism for autonomic dysreflexia) in a clinically-relevant calibrated clip-compression model of spinal cord injury in the rat. Autonomic dysreflexia was induced by colon distension in the conscious rats 2 weeks after severe (50-g) clip compression injury of the spinal cord at the 4th thoracic segment. The central arbor of small-diameter primary afferent fibers in laminae III-VII of the spinal cord dorsal horn was also assessed at 2 weeks after cord injury by quantitative morphometry, using calcitonin gene-related peptide as a marker. In response to colon distension, arterial pressure increased by 41 +/- 3 mmHg from a resting value of 109 +/- 4 mmHg, and heart rate decreased by 124 +/- 13 beats/min from a value of 515 +/- 16 beats/min (n = 7). Minimal locomotor function was recovered by these rats: by 2 weeks after injury they attained scores of only 3.1 +/- 1.3 on the Basso, Beattie and Bresnahan scale. Histopathology of the clip-compression lesion site in the cord consisted of extensive central necrosis extending several segments rostral and caudal to the lesion. Quantitative measures of the small-diameter afferent arbors revealed significant increases in area ranging from 20-27% in thoracolumbar segments caudal to the injury (n = 5) in comparison to sham-injured rats (n = 6). A second study was done to assess the impact of severity of injury on the relationship between the size of the primary afferent arbors and autonomic dysreflexia. At 2 weeks after milder (20-g) clip injury at T4, rats exhibited responses to colon distension that were not those associated with autonomic dysreflexia (n = 5). Arterial pressure increased by only 16 +/- 3 mmHg and heart rate tended to increase (+19 +/- 12 beats/min). These rats attained a locomotor score of 7.1 +/- 0.4 by 2 weeks. The lesions at the injury site also contained necrosis and mild cavitation within the gray matter. No change in the small-diameter afferent arbor was detected at 2 weeks after the 20-g clip injury at T4 (n = 6 rats). These findings suggest that after severe but not mild clip compression injury of the spinal cord, sprouting of the afferent component of the spinal reflex are contributes to the development of autonomic dysreflexia. Neither dysreflexia, nor changes in the afferent arbor size occurred after mild cord injury. This clinically relevant clip compression cord injury model, studied more frequently for locomotor function, is excellent for investigating mechanisms for the development of autonomic dysreflexia and strategies for its prevention.
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PMID:Autonomic dysreflexia and primary afferent sprouting after clip-compression injury of the rat spinal cord. 1168 96

Although it has been reported that the circulating adrenomedullin (AM) level is elevated in hypertension and renal failure, the pathophysiological significance of circulating and intrarenal AM in malignant hypertension remains unknown. We investigated the circulating and intrarenal AM system in rats with malignant hypertension by measuring the plasma level, renal tissue level, and mRNA abundance of AM and the mRNA abundance of AM receptor. We also investigated the effects of intravenously infused calcitonin gene-related peptide (CGRP)-(8-37), an antagonist of AM, on the hemodynamics and renal tubular function. We studied the following four groups: control Wistar-Kyoto rats (WKY), control spontaneously hypertensive rats (C-SHR), salt-loaded SHR (S-SHR), and DOCA-salt SHR (D-SHR). After 3 wk of DOCA treatment, D-SHR developed malignant hypertension. D-SHR were characterized by higher blood pressure, kidney weight, urinary protein excretion and blood urea nitrogen, and lower creatinine clearance compared with the other three groups. The plasma AM level and urinary excretion of AM were markedly higher in D-SHR than in the other three groups. In the kidney, the tissue AM level and the expression of AM mRNA in the renal medulla were significantly increased in D-SHR compared with the other three groups, whereas there were no significant differences in these levels in the renal cortex among the four groups. In the renal AM receptor system, the expression of the gene for receptor activity modifying protein 3 was significantly increased in the renal medulla in D-SHR compared with the other three groups. An immunohistochemical study revealed that AM immunostaining in renal collecting duct cells and distal tubules was more intense in D-SHR than in the other three groups. After CGRP-(8-37) infusion, blood pressure increased significantly and urinary sodium excretion and urine flow decreased significantly only in D-SHR. These results suggest that the increased circulating AM and renal AM and the increased expression of the mRNA for AM and its receptor may at least partly compensate for the malignant hypertensive state in certain forms of malignant hypertension via the hypotensive, natriuretic, and diuretic actions of AM.
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PMID:Role of increased circulating and renal adrenomedullin in rats with malignant hypertension. 1170 95

Most experimental studies of spinal cord injury have centered on the rat as an experimental model. A shift toward a mouse model has occurred in recent years because of its usefulness as a genetic tool. While many studies have concentrated on motor function and the inflammatory response following spinal cord injury in the mouse, the development of autonomic dysreflexia after injury has yet to be described. Autonomic dysreflexia is a condition in which episodic hypertension develops after injuries above the mid-thoracic segment of the spinal cord. In this study 129Sv mice received a spinal cord transection at the second thoracic segment. The presence of autonomic dysreflexia was assessed 2 weeks later. Blood pressure responses to stimulation were as follows: moderate cutaneous pinch caudal to the injury (35+/-6 mm Hg), tail pinch (25+/-7 mm Hg), and a 0.3 ml balloon distension of the colon (37+/-4 mm Hg). Previous reports have suggested that small diameter primary afferent fiber sprouting after spinal cord injury may be responsible for the development of autonomic dysreflexia. In order to determine whether autonomic dysreflexia in the mouse may be caused by a similar mechanism, the size of the small diameter primary afferent arbor in spinal cord-injured and sham-operated animals was assessed by measuring the area occupied by calcitonin gene-related peptide-immunoreactive fibers. The percentage increase in the area of the small diameter primary afferent arbor in transected over sham-operated spinal cords was 46%, 45% and 80% at spinal segments thoracic T5-8, thoracic T9-12 and thoracic T13-lumbar L2 respectively. This study demonstrates the development of autonomic dysfunction in a mouse model of spinal cord injury that is associated with sprouting of calcitonin gene-related peptide fibers. These results provide strong support for the use of this mouse model of spinal cord injury in the study of autonomic dysreflexia.
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PMID:Autonomic dysreflexia in a mouse model of spinal cord injury. 1173 3

Isolated segments (1-2 mm) of small subcutaneous arteries (diameter 0.1-0.9 mm) and veins (0.1-1.0 mm) from patients with hypertension (essential n = 13, renovascular n = 6) and controls (n = 17) were examined. The relaxant responses to the sensory transmitters calcitonin gene-related peptide (CGRP) and substance P, and the contractile responses to potassium and noradrenaline were studied. Enhanced dilatory responses (E(max)) but no change in sensitivity (pEC50) were demonstrated in the arteries but not in the veins to CGRP in hypertensives (P < 0.01) as compared with normotensives, and in the hypertensive subgroups (essential hypertension, P < 0.05; renovascular hypertension, P< 0.05). The relaxant responses to substance P were not altered either in arteries or in veins of hypertensives. Furthermore, there were no differences in the contractile responses to 60 mM potassium or to 10 microM noradrenaline between the groups. The results suggest that the enhanced vasodilator response to CGRP in hypertension is an adaptive reaction. The elevated blood pressure may be augmented by vasodilatory activity since different subgroups of hypertensives showed the same results. However, other common characteristics of hypertension (eg, medication, metabolic disturbances) may have also influenced the results.
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PMID:Enhanced vasodilator responses to calcitonin gene-related peptide (CGRP) in subcutaneous arteries in human hypertension. 1184 Feb 30

We have previously demonstrated that calcitonin gene-related peptide (CGRP) plays a counterregulatory role in subtotal nephrectomy-salt (SN-salt) hypertension through an increase in vascular responsiveness to the dilator activity of this neuropeptide. Substance P (SP) is often co-localized with CGRP in perivascular sensory nerves. To determine the role and mechanism of action of SP in SN-salt hypertension, we induced hypertension in 4- to 6-week-old male Sprague-Dawley rats (n=8) by subtotal nephrectomy and 1% saline drinking water. Sham-operated rats were given either tap water (n=9) or 1% saline to drink (n=9). Eleven to 13 days after each protocol, all rats had intravenous (for drug administration) and arterial (for continuous monitoring of mean arterial pressure [MAP]) catheters surgically implanted and were studied in the conscious and unrestrained state. Baseline MAP was significantly elevated in the SN-salt rats (157 +/- 6 mm Hg) compared with tap water--fed controls (128 +/- 3 mm Hg) and 1% saline--fed controls (132 +/- 5 mm Hg). Vehicle administration did not alter the MAP in any group. In contrast, administration of spantide-II (0.2 micromol/L in saline), an SP receptor antagonist, significantly elevated the MAP in SN-salt rats (13.9 +/- 0.8 mm Hg) compared with the tap water (1.7 +/- 1.7 mm Hg) and 1% saline controls (2.0 +/- 1.9 mm Hg). SP mRNA and peptide levels in dorsal root ganglia were not significantly different between the 3 groups. Administration of exogenous SP (12 and 24 nmol center dot L(-1) center dot kg(-1) intravenously) resulted in a significantly greater decrease in MAP in the SN-salt rats compared with both control groups. Taken together, these data suggest that in SN-salt hypertension, SP plays a counterregulatory role in the absence of an increase in its neuronal expression, thereby suggesting that one possible mechanism of this compensatory vasodilator response is enhanced vascular reactivity to SP.
Hypertension 2002 Feb
PMID:Substance P in subtotal nephrectomy-salt hypertension. 1188 78

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