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Biomedical subjects

M Aurell

Publications and source records attributed to M Aurell.

At least 163 records · Page 9Linked to original sources
PubMed1981

The role of prostaglandins in the alpha- and beta-adrenoceptor mediated renin release response to graded renal nerve stimulation.

The role of prostaglandins in the renin release response to renal nerve stimulation (RNS) at different intensities was examined in the anaesthetized dog. The animals were divided into two groups receiving either low or high level RNS, defined by the frequencies of stimulation producing reduction in renal blood flow by 5% or less and 50%. Indomethacin or diclofenac sodium (5 mg/kg i.v.), prostaglandin synthesis inhibitors, did not affect the renin release response to low level RNS but decreased the renin release response to high level RNS by 31 +/- 8% (P less than 0.01). Addition of metoprolol, (0.5 mg/kg i.v.) beta-1-adrenoceptor antagonist, to indomethacin or diclofenac sodium resulted in a greater reduction (68 +/- 6% P less than 0.01) of the renin release response to high level RNS compared to that produced by either drug alone. Metoprolol, alone, reduced the renin release response to high level RNS by 37 +/- 14% (P less than 0.05). Phenoxybenzamine (0.6 microgram . kg-1 . min-1), alpha-adrenoceptor antagonist, into the renal artery practically abolished the renal vasoconstrictor response to high level RNS and reduced the renin release response by 50 +/- 7% (P less than 0.01). Addition of metoprolol to phenoxybenzamine practically abolished the renal vasoconstrictor response and the renin release response to high level RNS; 94 +/- 4% (P less than 0.01). Addition of phenoxybenzamine to indomethacin or diclofenac sodium practically abolished the renal vasoconstrictor response to high level RNS but did not produce any greater reduction of the renin release response than that produced by either drug alone. These findings suggest that low level RNS results in renin release which is not dependent on prostaglandins. High level RNS results in renin release which is partly mediated by beta-1-adrenoceptors and partly related to alpha-adrenoceptors mediated renal vasoconstriction. Prostaglandins are not involved in the renin release deriving from alpha-adrenoceptor mediated renal vasoconstriction.

Animals↗
PubMed1981

Proximal tubular function in human hydronephrotic kidneys.

Proximal tubular was evaluated on the basis of the excretion rate of urinary beta-2-microglobulin of each kidney in 15 patients with unilateral hydronephrosis. Total and divided renal function was measured with 51chromium ethylenediaminetetraacetic acid clearance, isotope renography and a concentration test. Total renal function was normal in all patients. Parenchymal function, measured by renography, was reduced in 2 hydronephrotic kidneys and both patients had had upper urinary tract infections. The ability to concentrate urine was impaired in 10 hydronephrotic kidneys. These patients had renal calculi or had had upper urinary tract infections. The urinary beta-2-microglobulin excretion was normal in all hydronephrotic kidneys, indicating an intact proximal tubular function in these patients.

Adolescent↗
PubMed1981

Renal function and biopsy findings in patients on long-term lithium treatment.

Nine patients on long-term lithium treatment (3 to 13 years) had abnormal renal function with a decreased GFR and/or a decreased maximal urinary concentration capacity. Four patients had received lithium as the only drug, whereas five patients had had concomitant treatment with neuroleptics. No patient had a history of nephrourological diseases. Abnormal renal morphology was present in the biopsy samples from all patients. Cortical fibrosis was found in a variable degree. Dilated tubules and microcysts in which the epithelial lining was clearly abnormal were found in majority of samples. Electron micrographically, two types of abnormal epithelial cells were observed, one with small elongated mitochondria with dense matrix and the other with large spherical and less dense mitochondria. In distal tubules, mitochondrial swelling, accumulation of cytosegrosomes, and nuclear pyknosis dominated the picture. These findings indicate a tubulointerstitial nephropathy and support the hypothesis that long-term lithium treatment may cause renal damage in susceptible patients.

Adult↗
PubMed1981

Blood pressure and the renin--angiotensin--aldosterone system.

1. The relationships between blood pressure and the components of the renin--angiotensin--aldosterone system were studied in 49-year-old men (n = 120) who were selected at random from the total population so as to be representative of all blood pressure levels. 2. Only plasma aldosterone concentration was significantly correlated with blood pressure, both in the whole study group (r = 0.22; P less than 0.02) and in the hypertensive blood pressure range (r = 0.36; P less than 0.02). The hypertensive subjects had a significantly higher plasma aldosterone concentration than the borderline and normotensive subjects. 3. Multiple regression analysis including factors related to the renin--angiotensin--aldosterone system, showed that the 24 h urinary excretion of noradrenaline was the factor most strongly correlated to plasma aldosterone. 4. The findings indicate that aldosterone may be the most important component of the renin--angiotensin--aldosterone system in the development and maintenance of essential hypertension.

Aldosterone↗
PubMed1981

Effect of prenalterol, a beta-1-adrenoceptor agonist, on renin secretion rate in the anaesthetized dog.

The effects of the beta-1-adrenoceptor agonist, prenalterol, 20 microgram/kg intravenously on renin secretion rate (RSR), renal haemodynamics and sodium excretion were examined in anaesthetized dogs with innervated or denervated kidneys. In dogs with innervated kidneys, prenalterol increased RSR from 1.1 +/- 0.2 to 7.9 +/- 0.1 units X min.-1 X g-1 (P less than 0.01). Prenalterol did not affect mean arterial pressure, renal blood flow, glomerular filtration rate or sodium excretion. Heart rate was increased by 53 +/- 17 beats/min. (P less than 0.01). The increase in RSR produced by prenalterol was independent of intact renal innervation as RSR increased to the same extent in dogs with denervated kidneys. Pretreatment with the beta-1-adrenoceptor antagonist, metoprolol 0.5 mg/kg intravenously, abolished the increase in RSR produced by prenalterol. These findings suggest that prenalterol directly activates renal beta-1-adrenoceptors to increase RSR.

Adrenergic beta-Agonists↗
PubMed1981

Reference values for 51Cr-EDTA clearance as a measure of glomerular filtration rate.

Reference values for glomerular filtration rate (GFR) were defined using eight reports including epidemiological studies and studies in kidney donors. Studies using both inulin and 51Cr-EDTA were included. GFR decreased with age, by 4 ml/min decade below the age of 50, and 10 ml/min decade above 50 years of age. No sex difference was found. +/- 2 SD was equal to 25 ml/min at all ages. Based on these findings a nomogram for GFR is presented. Emphasis is given to the use of plasma clearance of 51Cr-EDTA estimated with single injection technique as the new reference method for GFR measurement.

Adolescent↗
PubMed1981

The use of living donors. Glomerular filtration rate during the first year after donor nephrectomy.

The functional increase in the remaining kidney after donor nephrectomy has two distinct components in man. There is a rapid initial increase in function within the first 24 hours, due to the circulatory adjustments in the kidney, but the mechanisms have not been elucidated. Thereafter, there is a further functional increase during the first year which in addition to the haemodynamic changes, also includes an increase in tubular function. The increased work-load on the kidney handling the increased volume of filtrate presented to the tubules may induce the increase in tubular function, but hormonal factors have been shown to contribute to the long-term increase in tubular function after contralateral nephrectomy.

Adult↗
PubMed1981

Nine years' follow-up of a maximal exercise test in a random population sample of middle-aged men.

A stepwise bicycle exercise test up to maximum was performed in a random population sample of 793 Swedish men, all aged 54 years. High respiratory rate during exercise characterized those who later suffered myocardial infarction (MI) or sudden coronary death (SD). In addition to high cholesterol, high blood pressure (BP), and smoking, low maximal performance, but not ST changes during exercise, increased the risk of MI + SD also in multivariate analysis. Pulse rate, systolic BP at both submaximal and maximal work load were positively correlated with the initial blood pressure level. BP at these work loads was also positively correlated with subsequent BP increase.

Blood Pressure↗
PubMed1980

The role of beta-1-adrenoceptors in the renin release response to graded renal sympathetic nerve stimulation.

The contribution of beta-adrenoceptor activation to renin release was examined in anaesthetized dogs using renal nerve stimulation (RNS) at different discharge rates in the presence of i.v. beta-adrenoceptor blockade. The animals were divided into 2 groups, which received either low or high level of RNS, defined by the frequency of stimulation producing decrease in renal blood flow of 5 and 50%, respectively. Low level RNS increased renin release tenfold. The renin release response was almost abolished by 0.5 mg/kg of metoprolol or dl-propranolol but unaffected by 0.5 mg/kg of d-propranolol. The increase in renin release to high level RNS was equally reduced by 33% by 0.5 mg/kg and 2.0 mg/kg of metoprolol. dl-propranolol, 0.5 mg/kg, reduced the renin release response to about the same extent, 44%, while 2.0 mg/kg reduced it somewhat more, 59%. This was probably due to its membrane stabilizing properties as d-propranolol, 2.0 mg/kg and lidocaine 2.0 mg/kg + 0.1 mg x kg-1 x min-1, also reduced the renin release response. These data suggest that the renin release response to low level RNS is almost completely mediated by beta-adrenoceptors which are of the beta-1 subtype. High level RNS results in a renin release, which is only partly mediated by beta-1-adrenoceptors. The remainder is apparently related to other mechanisms activated by high level RNS and is probably a consequence of the associated renal vasoconstriction.

Adrenergic beta-Antagonists↗
PubMed1980

Blood pressure and renal function.

The relationship between blood pressure (BP) and renal function was studied in samples of 49-year-old men. Of 3 205 49-year-old men, 2 376 (74%) took part in a BP screening. By systematic sampling, based on diastolic BP levels varying from very low to very high, 120 subjects were selected for this study. Only subjects who were not on antihypertensive treatment were included. Renal blood flow (RBF), renovascular resistance (RVR), glomerular filtration rate (GFR), filtration fraction (FF) and renal concentrating capacity were studied in 111 subjects, none of whom had advanced hypertension. With increasing BP there was a decrease in RBF (r = -0.34) and an increase in RVR (r = 0.81) and FF (r = 0.35). The changes in renal haemodynamics occurred gradually from low to high BP, and did not start at any particular BP level. With increasing BP, GFR was unchanged. An "autoregulation of GFR" was thus found at all BP levels studied. Renal concentrating capacity was unchanged. These findings indicate that renal haemodynamics in essential hypertension are adjusted mainly to ensure a constant GFR.

Blood Pressure↗
PubMed1980

Diuretic urography in the assessment of obstruction of the pelvi-ureteric junction.

Twenty adult patients with urographic evidence of unilateral, moderately wide renal pelves were examined by routine and diuretic urography. Planimetry of the corresponding calyx system of the two examinations was performed. An increase in size by more than 20 per cent following osmotic diuresis indicated an obstruction of the pelvi-ureteric junction in kidneys with moderately wide renal pelves. Diuretic urography may be useful to diagnose obstruction as a cause of moderately wide renal pelves and to assess operative results.

Adult↗
PubMed1980

Methodological aspects of renography in children.

Kidney function in children by renography has been evaluated. For reproducible results a high degree of standardization with respect to position, hydration and dosage was necessary. The wide range of kidney size and depth in children requires age-adapted collimators. For practical use for different size have been constructed for the age-groups: less 1 year, 1-5 years, 6-9 years and 10-15 years. A reduction in the surrounding activity of the kidneys is thereby obtained and disturbing influence from the bladder or contralateral kidney is prevented. Kidney function variables from the renogram are presented in terms of uptake and excretion ratios. The correlation between sum of uptake ratios and clearance measurements is good in cases with slight or moderate difference in kidney size. The standardized renographic technique has many advantages for kidney function measurements in children. The method is applicable in all ages, it is simple and reliable without extensive preparations and requires a low radiation dose. Also in children we can confirm the previous opinion obtained in adults that renography is a clinical valuable method of measuring kidney function.

Adolescent↗
PubMed1980

Evaluation of unilateral kidney function in children. A comparison between renography and separate clearance.

Unilateral kidney function in children was evaluated by determination of 51Cr-EDTA-clearance combined with estimation of side distribution of kidney function by renography. As reference, separate clearance of 51Cr-EDTA, determined by sequential external ureteral occlusions on both sides, was used. A comparison between these two methods was made in 28 patients with varying degrees of unilateral kidney function impairment. A significant correlation was found when the renograms were corrected for extrarenal background activity. Thus, renography in combination with determination of the glomerular filtration rate with 51Cr-EDTA is a valuable method for evaluating separate kidney function in children, both methods being easily performed and requiring small radiation doses.

Adolescent↗
PubMed1979

Fibromuscular dysplasia of the renal arteries.

Two cases of severe fibromuscular dysplasia of the renal arteries are described in which the diagnosis was made 12 and 11 years after renal angiography had shown the arteries to be normal. The discovery of hypertension preceded the diagnosis by two and 11 years respectively, and in one case hypertension was present at the time of the normal renal angiogram. The report suggests that fibromuscular dysplasia of the renal arteries is acquired and may not be present from birth. The importance of regular review in cases of severe hypertension is emphasised.

Adult↗