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

The spontaneous changes in renal plasma flow (RPF) were determined by sodium paraamino hippurate clearance (CPAH) in the individual kidneys of 71 patients with essential and secondary hypertension. These changes were expressed as changes in CPAH and as changes in CPAH per 100 ml Glomerular Filtration Rate (GFR = inulin clearance) for every individual kidney. Sixteen normal subjects were used as control. The RPF changes were measured between two consecutive 10 minute clearance periods during separated kidney function tests. In all the hypertensive groups studied, when RPF variability was expressed per 100 ml GFR, the variability was found to be two to five times greater than in normals. This findings suggests that in the hypertensive state the blood flow changes in the kidney are more labile than in normals. The high lability of renal blood flow could reflect and abnormality in renal vascular tone. This abnormality could be an important factor in the pathogenesis and maintenance of high blood pressure.
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PMID:High renal plasma flow lability in the kidneys of hypertensive patients. 68 55

Hypervolemia with hypertension often occurs 36-72 hours following massive blood and fluid replacement for hypovolemic shock. This syndrome of "fluid overload" has been attributed to the rapid intravascular flux of previously sequestered fluid in patients with impaired diuresis. This hypothesis was tested in 35 injured patients who received a mean of 9.3 L of blood and 17.4 L of salt during resucitation. The renal parameters measured soon after resuscitation included: 1) renal clearance of inulin (GFR), para-amino hippurate (ERPF), milliosmoles, sodium, and free water; 2) inulin space, renal vascular resistance (RVR), O2 consumption, renin, renal blood flow (RBF), and response to furosemide. Eighteen patients developed hypertension, hypervolemia, and respiratory insufficiency. When compared to the 17 normovolemic, non-hypertensive patients, the 18 hypervolemic patients had significantly increased RVR, with a significant decrease in RBF despite an increase in plasma volume and cardiac output. Furosemide produced less diuresis and natriuresis in the hypertensive patients. The balance between hypovolemia and "fluid overload" seemed percarious in the hypertensive patients. Peripheral renin and catecholamine levels were normal in both groups. Patients with post-traumatic "fluid overload" appear to have a combination of hypervolemia, respiratory insufficiency, hypertension, increased cardiac output, decreased extracellular fluid space, and decreased renal perfusion. These findings suggest that decreased interstitial fluid space compliance rather than "fluid overload" is the underlying factor leading to respiratory insufficiency. The therapeutic aspects of these findings are discussed.
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PMID:The renal factor in the post-traumatic "fluid overload" syndrome. 89 57

Glomerular hyperfiltration and hypertension induced by extensive loss of renal parenchyma are suspected to accelerate progression of renal failure. Amino acid infusion or protein ingestion also modify renal hemodynamics and increase glomerular filtration rate (GFR). This phenomenon was used to study the influence of two commonly used antihypertensive agents, captopril and nifedipine, on renal hemodynamics at rest and during glomerular hyperfiltration. Thirteen healthy volunteers were studied on three separate days (days A, B, and C) in random sequence: inulin and p-amino hippurate (PAH) clearance were measured first under glucose infusion and afterwards under stimulation by amino acid infusion (0.35 mmol/kg/min; 4 mg/kg/min). Day A served as a control, where no medication was given. On day B, 10 mg nifedipine, and on day C, 25 mg captopril, were administered orally before study. Without premedication (= day A, control) GFR increased from 108.0 +/- 6.9 mL/min (SEM) to 131.7 +/- 7.0 mL/min (P less than 0.05). On day B (nifedipine), GFR before stimulation by amino acids was already elevated to 121.8 +/- 4.2 mL/min (P less than 0.05 compared with day A) and increased to 132.6 +/- 6.3 mL/min with infusion of amino acids, thus to the same range as on day A without medication. On day C, after captopril, GFR did not increase with infusion of amino acids (from 112.5 +/- 7.2 to 117.3 +/- 6.3 mL/min). Our results indicate the calcium channel antagonist nifedipine and the angiotensin-converting enzyme (ACE) inhibitor captopril differ in their effect on intrarenal hemodynamic parameters. Nifedipine induces hyperfiltration at rest and allows maximal hyperfiltration to develop under amino acid infusion.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of nifedipine and captopril on glomerular hyperfiltration in normotensive man. 149 65

Split intrarenal hemodynamics in stenotic and contralateral kidneys of unilateral renovascular hypertension (RVH) were estimated by Gomez's formulae. Ten patients with RVH were studied. Split para-amino hippurate and inulin clearances were measured by ureteral catheterization as indexes for renal plasma flow and glomerular filtration rates, allowing the estimation of intrarenal hemodynamics such as preglomerular arteriolar resistance, postglomerular arteriolar resistance and glomerular hydrostatic pressure in each kidney. Renal plasma flow and glomerular filtration rates were lower in the stenotic kidney (83 +/- 12, 19 +/- 2 ml/min/m2) than in the contralateral kidney (170 +/- 19, 43 +/- 4). Preglomerular arteriolar resistance was elevated due to the stenotic lesion in the stenotic kidney (30,900 +/- 4,500 dyns.sec.cm-5) while the elevation in the contralateral kidney (11,300 +/- 1,000) was less. Postglomerular arteriolar resistance was high in both kidneys. Glomerular pressure was lowered in the stenotic kidney (54 +/- 1 mmHg), while elevated in the contralateral kidney (71 +/- 3). Although the stenotic kidney of RVH was protected from systemic hypertension (138 +/- 6 mmHg) by stenosis of the renal artery, the increase in preglomerular arteriolar resistance in the contralateral kidney was not sufficient, making glomerular pressure elevated. Thus, glomerular hypertension and hyperfiltration were demonstrated in the contralateral kidney of RVH.
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PMID:Split intrarenal hemodynamics in renovascular hypertension. 179 8

The mechanism of action of angiotensin converting enzyme (ACE) inhibitors on urinary albumin excretion (UAE) in diabetics is controversial. In order to dissociate the hypotensive and intrarenal effects, 16 insulin-dependant diabetics with permanent microalbuminuria (30-300 mg/24 h) without hypertension were given Ramipril, a long acting ACE inhibitor, at hypotensive (treatment A 5 mg/day; N = 8) and at sub-hypotensive doses (treatment B, 1.25 mg/day; N = 8) over a 6 week period in parallel double-blind study. Blood pressure, UAE, glomerular filtration renal blood flow (continuous 125I-Iodothalamate + 131I-Hippurate infusion) and converting enzyme activity (Liebermann's method), before and after treatment. In treatment group A, the blood pressure fell from 133 +/- 5/79 +/- 4 (mean +/- SE) to 125 +/- 4/77 +/- 2 mmHg (p less than 0.05 for systolic blood pressure) whereas it remained stable in treatment group B (132 +/- 7/79 +/- 4 to 128 +/- 5/80 +/- 4 mmHg). The UAE decreased in both groups: group A from an average of 74 (40-198) to 47 (5-202) mg/24 h (p = 0.07; group B, from an average of 77 (50-136) to 19 (15-120) mg/24 h (p less than 0.005), as did ACE activity: group A from 332 +/- 44 to 163 +/- 33 iu/l (p less than 0.004), group B from 423 +/- 39 to 191 +/- 28 iu/l (p less than 10-4).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Dissociation of hypotensive and renal hemodynamic effects of an angiotensin converting enzyme inhibitor in insulin-dependent diabetic patients with incipient nephropathy]. 182 59

Research in nephrologic nuclear medicine is presently concentrated in two well-defined areas: interventional procedures and the use of mercaptoacetyltriglycine. The ongoing evaluation of mercaptoacetyltriglycine continues to be a source of interesting research activity, with the distribution volume and the extent of hepatic excretion remaining points of discussion. This tracer permits quantitative determination of renal function. As an imaging agent, mercaptoacetyltriglycine compares favorably with hippurate and with diethylenetriamine penta-acetic acid, particularly in evaluating renal insufficiency. Renal function studies obtained during pharmacologic or physiologic intervention dominate research in hypertension and obstructive uropathy. Angiotensin-converting enzyme inhibition improved the renographic detection of renovascular lesions. Interventional renography with angiotensin-converting enzyme inhibition or ergometric exercise were both capable of generating useful prognostic data on the posttherapy blood pressure response in patients with renovascular hypertension. Interventional diuretic renography with furosemide permits surgical intervention to be reserved for organs at immediate risk because the degree of obstruction and the extent of renal function compromise are easily recognized.
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PMID:Renal studies in nuclear medicine. 183 42

Activity of serum angiotensin converting enzyme (SACE) was measured in serum of 33 pregnant women with normal blood pressure or pregnancy induced hypertension (PIH), using sensitive Hippurate colorimetric micromethod. The mean level of SACE activity in 17 PIH patients (73.25 +/- 18.81 U/ml) was significantly higher than that in normotensive pregnant women (16 cases) ( 52.36 +/- 9.91 U/ml) (P less than 0.01). The mean arterial blood pressure showed a positive correlation with the level of SACE activity in all pregnant women (Y = 69.089 + 0.494x, r = 0.562, P less than 0.01). In PIH patients, the gestosis index and degree of edema also had statistically significant correlation with the level of SACE activity (Y = -0.560 + 0.056x, r = 0.549, P less than 0.01) (Y = -1.760 + 0.043x, r = 0.629, P less than 0.05). The amount of 24h urinary protein was independent of the level of SACE activity. It suggests that disturbance in regulation of ACE activity may be one of the factors responsible for the development of PIH.
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PMID:[Activity of serum angiotensin converting enzyme in pregnancy-induced hypertension]. 184

Since the advent of extracorporeal shock wave lithotripsy (ESWL) concern has surfaced as to the long-term risk of the development of hypertension, as well as risk to the developing kidney. To study this concern 8 infant and 3 adult rhesus monkeys (Macaca mulatta) underwent treatment with the XL1 experimental lithotriptor to 1 kidney varying the amount of voltage and shocks. Followup consisted of measurement of renin levels and quantitative renal scans, using 131iodine hippurate to calculate effective renal plasma flow. In the infants a slight change was noted in the absolute effective renal plasma flow of the treated kidney versus the untreated side but it was not statistically different. When indexed to body surface area in the growing animal, there was a statistically significant decrease in renal function. However, peripheral renin levels were markedly elevated in the infants at 3 weeks, and they gradually declined during the 6-month period, although levels remained elevated over baseline. The adults also had central renin levels drawn from the renal vein on the treated side, and there was a close correlation with the peripheral levels, which peaked at 3 weeks and returned to normal. Thus, it seems that at least in the short term renin production is increased in infants more than adults. This finding may be an indicator as to renal damage and is a possible explanation for hypertension occurring after ESWL.
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PMID:Renin production after experimental extracorporeal shock wave lithotripsy: a primate model. 186 Dec 97

Renal artery stenosis with resultant renovascular hypertension has attracted clinical attention because the disease is potentially curable and because numerous diagnostic and therapeutic modalities compete for clinical acceptance. An exercise-mediated disturbance of renal hippurate transport was recently described, and has been implicated as having a role in nephrogenic fixed hypertension. To predict the final course of renovascular hypertension before operation we carried out a prospective study with the goal of verifying the predictive value of exercise hippurate scintigraphy. The study was to test the hypothesis that patients with disturbance of renal hippurate transport (pathologic renogram) induced by exercise would have stabilized hypertension and would continue to be hypertensive after operation. Thirty-one patients with hypertension who had unilateral or bilateral renovascular stenosis documented on angiography were referred to rest and exercise hippurate scintigrams before operation. The results of the examinations at rest served as standard and were compared with the exercise scintigrams. In 19 of the 31 (61%) patients a disturbance of transrenal hippurate transport evolved during exercise, whereas 12 (39%) patients failed to respond to exercise with altered hippurate kinetics. Twenty-six patients went on to renovascular operations; five had percutaneous transluminal angioplasty. Revascularization results differed markedly when the blood pressure response of patients with positive results on exercise (abnormal) and patients with negative results on exercise (normal) were compared. Ten of 12 patients with hypertension who had normal exercise renograms were cured. In comparison, blood pressure values were little influenced by therapy in patients with an abnormal response, where 17 of 19 patients continued to have hypertensive disease after therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renovascular hypertension: predicting surgical cure with exercise renography. 186 32

Split intrarenal hemodynamics in stenotic and contralateral kidneys of unilateral renovascular hypertension (RVH) were estimated by Gomez's formulae. Forty patients with essential hypertension and 40 patients with RVH were studied. Split para-amino hippurate and inulin clearances were measured by ureteral catheterization as indexes for effective renal plasma flow and glomerular filtration rates, allowing the estimation of intrarenal hemodynamics such as afferent arteriolar resistance (RA), efferent arteriolar resistance (RE) and glomerular hydrostatic pressure (PG) in each kidney. Normal values of intrarenal hemodynamic parameters were obtained in 24 normotensive subjects without ureteral catheterization, assuming each kidney had the half function of both kidneys. Systemic mean arterial pressure did not differ between essential and renovascular hypertension (141 +/- 3 vs. 148 +/- 3 mm Hg). Effective renal plasma flow and glomerular filtration rates were decreased in the stenotic kidney of RVH (98 +/- 8, 24 +/- 2 ml/min/m2), while increased in the contralateral kidney (195 +/- 11, 48 +/- 2), compared with the right kidney of essential hypertension (162 +/- 8, 33 +/- 1). Although effective renal plasma flow rate was not different from normal (191 +/- 8), glomerular filtration rate was significantly higher in the contralateral kidney of RVH than in normal (38 +/- 1). RA was elevated due to the stenotic lesion in the stenotic kidney (28,500 +/- 1,900 dyns.sec.cm-5), while the elevation in the contralateral kidney (10,800 +/- 600) was less than in the right kidney of essential hypertension (14,900 +/- 1,200). RE (5,800 +/- 300) in both kidneys of RVH was higher than in the right kidney of essential hypertension (4,500 +/- 200).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glomerular hypertension in renovascular hypertensive patients. 206 13


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