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

The pathogenetic relationship between tumor and hypertension was investigated in 40 patients with renal cell carcinoma. 15 of 40 patients were hypertensive. Four of these 15 patients with renal tumors and hypertension (26.7%) were found to have primary reninism. In these patients the plasma renin activity in blood from the renal veins showed a tumor kidney to contralateral kidney ratio of between 6 and 7. In the same 4 cases the renin content in the renal tumor tissue was significantly higher than that in tissue from the adjacent tumor-free renal cortex of the ipsilateral kidney. Immunocytochemical demonstration of renin in the tumor was only possible in these 4 cases. In 3 of these patients blood pressure returned to normal following nephrectomy; in the 4th case there was a drop in blood pressure after nephrectomy. Renin-producing renal cell carcinomas are an uncommon cause of renal hypertension. The differential diagnosis of hypertension should therefore also include renal tumor.
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PMID:Renin-producing renal cell carcinoma. 220 1

Renin and catecholamine levels were determined in patients with mild to moderate hypertension before and after treatment with sustained release diltiazem or captopril and were correlated with the blood pressure response to these antihypertensives. Eight weeks of treatment with either agent led to equal decreases in both systolic and diastolic blood pressure. Pretreatment plasma renin activity (PRA) and plasma norepinephrine did not predict the blood pressure response to either agent. Diltiazem significantly increased both PRA and supine norepinephrine levels. However, in the diltiazem treated patients, there was no correlation between the change in plasma norepinephrine and the change in systolic or diastolic blood pressure. In contrast, there was a negative correlation (P less than .05) between the reactive rise in PRA and the decrease in systolic blood pressure. Thus, the antihypertensive response to a calcium channel blocker may be determined, in part, by the reactive response of pressor systems.
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PMID:Humoral factors determining the blood pressure response to converting enzyme inhibition and calcium channel blockade. 222 51

To assess the rate of activation of the renin-angiotensin-aldosterone axis and enhancement of adrenal responsiveness to angiotensin II (Ang II) with restriction of sodium intake, 16 healthy male subjects were placed initially on a 200 meq daily sodium intake; adrenal responsiveness to Ang II was assessed, and then daily sodium intake was reduced abruptly to 10 meq. Adrenal responses to Ang II were assessed again during the non-steady state interval 24 and 48 hours later, and after balance was achieved in 5-7 days. Renin-angiotensin system activation was evident within 24 hours after sodium intake was restricted. The increase in basal plasma aldosterone concentration and enhancement of the adrenal response to Ang II, on the other hand, tended to lag. Within 24 hours of restricting sodium intake, despite a significant increase in both plasma renin activity (1.0 +/- 0.2 vs. 2.4 +/- 0.7 ng/ml/hr, p less than 0.01) and Ang II concentration (22.0 +/- 1.9 vs. 29.5 +/- 1.3 pg/ml, p less than 0.05), there was no increase in basal plasma aldosterone concentration (10.4 +/- 1.3 vs. 11.7 +/- 1.2 ng/dl). At 48 hours, despite little further change in plasma renin activity or plasma Ang II concentration, there was a sharp increase in basal plasma aldosterone concentration (22.5 +/- 3.6 ng/dl, p less than 0.01). The adrenal response to Ang II was increased significantly at 24 hours, evident at only a 10 ng/kg/min dose, but showed progressive further enhancement with time.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1990 Apr
PMID:Time course of enhanced adrenal responsiveness to angiotensin on a low salt diet. 231 19

Noradrenaline (NA) and dopamine (DA) have opposite effects on the kidney; NA causes vasoconstriction and increased sodium reabsorption while DA promotes vasodilation and natriuresis. In 15 patients investigated for renin-mediated hypertension measurements of plasma renin activity (PRA), NA and DA concentrations were made in arterial and renal venous blood from both kidneys before and after acute stimulation of renin release by i.v. dihydralazine. Nine patients had unilateral renin secretion and were classified as renin-positive, while the remaining six patients were renin-negative. Renin-positive patients had higher arterial and renal venous PRA, NA and DA levels than the negative ones. In the renin-positive group V-A differences for NA and DA were present on both sides despite unilateral secretion of renin. NA but not DA levels were higher in the renin-secreting kidney, which can partly be explained by the reduced plasma flow to the involved kidney. After dihydralazine the arterial NA and DA rose similarly in renin-positive and renin-negative patients, while PRA rose only in the renin-positive cases. In the renin-positive patients where stimulation of renin secretion caused a marked increase of the PRA gradient on the affected side only, renal gradients for NA and DA increased bilaterally. The increase in DA was more pronounced than that of NA yielding a rise in DA/NA ratio on the affected side. Arterial PRA was positively correlated to the plasma concentrations of NA and DA. V-A differences for PRA and NA or DA were positively correlated on the involved renin-secreting side. In summary, patients with renin-dependent hypertension have elevated plasma NA and DA concentrations. Stimulation of renin release by dihydralazine increases the DA/NA ratio in arterial and renal venous blood indicating release of 'precursor dopamine' from noradrenergic fibres and/or activation of dopaminergic nerves. There seems to be a relationship between renal nerve activity and renin release in renin-dependent hypertension.
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PMID:Plasma noradrenaline and dopamine in renin-mediated hypertension. 240 2

The present study analyzed the concentration of renin-like activity and angiotensinogen concentration (AoC) in different brain areas related to cardiovascular control in SHR and Wistar Kyoto (WKY) animals. Male rats of both strains were studied at 8, 16 and 30 weeks of age. The following brain areas were isolated: anterior, medial and posterior hypothalamus, septal area, periaqueductal gray (PG) and the remaining brain stem; nucleus tractus solitarius (NTS) and the remaining medulla oblongata. Plasma renin activity (PRA) and plasma and cerebrospinal fluid (CSF) AoC were determined. Renin-like concentration was higher in SHR than in WKY in the anterior hypothalamus, PG and NTS at different stages of hypertension development. AoC was also higher in some areas of the SHR brain during different periods. PRA, plasma and CSF angiotensinogen concentration showed significant differences between both strain of rats during the development of high blood pressure. Present data support the possibility that the central and peripheral renin-angiotensin system may participate in the maintenance of high blood pressure in the SHR animals.
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PMID:The renin-angiotensin system in different stages of spontaneous hypertension in the rat (S H R). 240 92

The use of antirenin antibody and Fab may provide a more specific physiologic tool and potential therapeutic agent than the existing pharmacologic inhibitors. The antibody combining site, by virtue of its larger size than organic compounds, has the capacity for a larger number of intramolecular contacts with its ligands, thus allowing increased selectivity and affinity. Renin-specific IgG and Fab obtained through immunization with purified dog renal renin have been studied. These agents had no effect on blood pressure in the sodium-replete conscious dog but induced systemic depressor responses in the sodium-depleted animal or during acute renovascular hypertension. These responses were accompanied with complete suppression of plasma renin and angiotensin II levels. Since antibodies and their fragments derived from immune sera are limited in their application to physiologic study with respect to lack of homogeneity, reproducibility, and limitation of quantity, monoclonal antibodies to purified human renal renin have also been obtained. Administration of monoclonal antibodies to conscious monkeys yielded similar overall cardiovascular responses as polyclonal antisera. These studies indicate that antirenin antibodies are highly potent and specific tools for physiologic studies and are of potential clinical usefulness.
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PMID:In vivo inhibition of renin by antirenin antibodies: potential experimental and clinical applications. 241 14

The possible role of vascular angiotensin converting enzyme (ACE) is examined in vitro and in vivo. In helically cut strips of arteries isolated from dogs, contractions induced by angiotensin (ANG) I are suppressed by ACE inhibitor or ANG II antagonist. This indicates that vascular ACE contributes to the local formation of ANG II. In two-kidney, one-clip hypertensive rats, plasma-renin activity (PRA) rises rapidly with the elevation of blood pressure, then decreases gradually, despite sustained high blood pressure. Renin activity in the aorta also increases with the development of hypertension and then decreases in parallel with PRA. ACE activity in plasma does not change before or after the unilateral occlusion of the renal artery until after 16 weeks, whereas the enzyme activity in the aorta significantly increases. The conversion rate calculated from the pressor responses, and from the constricting effects of ANG I and ANG II, both in situ and in helically cut strips obtained from chronic hypertensive rats with increased vascular ACE activities, are significantly higher than those obtained from normotensive rats. Vascular ACE, which can effectively produce ANG II from ANG I locally, appears to play an important role in the maintenance of chronic hypertension.
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PMID:Vascular angiotensin converting enzyme in the development of renal hypertension. 243 92

Renin messenger (m) RNA distribution was studied in congenital mesoblastic nephroma, a usually benign renal tumour of early infancy which may be associated with excess renin production and hypertension. Using in situ hybridization with synthetic radiolabelled oligonucleotide probes combined with immunohistochemical studies, renin expression was found in areas of tumours containing recognizable cortical structures including glomeruli and tubules. Renin mRNA was also detected in vessels and larger vascular spaces within the tumour not associated with cortical structures. Cells in the tumour vessel walls and sinusoids which expressed renin also stained positively for vascular smooth muscle-specific alpha actin.
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PMID:Renin messenger RNA localization in congenital mesoblastic nephroma using in situ hybridization. 255 58

To clarify the relationship between kallikrein-kinin and renin-angiotensin systems, glandular kallikrein, renin and angiotensin converting enzyme in the submandibular gland, the kidney and plasma were investigated in streptozotocin diabetic and spontaneously hypertensive rats. Kallikrein content in the submandibular gland, the kidney and plasma of diabetic rats was found to be decreased compared with nondiabetic controls. Renin activity in diabetic rats was also reduced in the submandibular gland, but the activity showed no significant changes in the kidney and plasma. The activity of angiotensin converting enzyme (ACE) in plasma significantly increased in diabetic rats. On the other hand, kallikrein content in hypertensive rats was depressed in the kidney, while the content was unchanged in the submandibular gland and plasma. Renin activity in hypertensive rats was found to be higher than that of normotensive rats in the submandibular gland, but the activity showed no remarkable changes in the kidney and plasma. ACE activity in plasma markedly decreased in hypertensive rats in contrast to diabetic rats. In hypertensive-diabetic rats, changes in the levels of these enzymes in tested materials were similar to those of diabetic rats. From these results it is reasonable to assume that (1) reduced kallikrein generation and elevated ACE activity may induce impaired kinin formation and contribute to the development of diabetes mellitus apart from the presence of hypertension and (2) low kallikrein content in the kidney could cause hypertension.
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PMID:Glandular kallikrein, renin and angiotensin converting enzyme of diabetic and hypertensive rats. 255 14

The cause and mechanism of post-carotid endarterectomy hypertension remains unknown. To determine the influence of the sympathetic and renin-angiotensin system, we measured cranial and peripheral plasma levels of catecholamine and renin in patients undergoing carotid endarterectomy. Baseline samples were drawn just before carotid clamping (sample I) and compared with study samples drawn immediately after clamp release (sample II), 2 to 6 hours after surgery (sample III), and then 18 to 24 hours after surgery (sample IV). The patients with post-carotid endarterectomy hypertension had an associated increase of cranial and peripheral norepinephrine levels in the postoperative hypertensive period whereas the patients without post-carotid endarterectomy hypertension did not. This association was most pronounced and statistically significant in cranial samples II (p = 0.032) and III (p = 0.005). Epinephrine and dopamine values did not correlate with post-carotid endarterectomy hypertension. Renin values were higher in cranial than in peripheral samples at time period 2 (p = 0.011), suggestive of a central nervous system Goldblatt phenomenon. However, the renin values did not correlate with post-carotid endarterectomy hypertension. We conclude that post-carotid endarterectomy hypertension is associated with elevated cranial norepinephrine levels, suggestive of a central nervous system sympathomimetic mechanism. Optimal prevention and treatment of this brief but frequently occurring hypertension should include a central-acting sympatholytic agent.
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PMID:Post-carotid endarterectomy hypertension: association with elevated cranial norepinephrine. 264 44


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