Biomedical subjects
M Aurell
Publications and source records attributed to M Aurell.
Assessment of renal concentrating ability.
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Pathophysiological mechanisms of the antihypertensive effect of a cardioselective beta-adrenoceptor blocking drug (metoprolol).
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Sodium balance and structural vascular changes in the kidney during development of hypertension in spontaneously hypertensive rats.
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Maximum urinary concentration ability in patients with idiopathic hydronephrosis.
The maximum urinary concentration ability and renal parenchymal function of each kidney were investigated in 34 patients with unilateral hydronephrosis. The ability to concentrate urine was not reduced in 10 hydronephrotic and 24 contralateral kidneys. The concentration ability was moderately reduced in 14 hydronephrotic and 10 non-hydronephrotic kidneys and severely impaired in 10 hydronephrotic kidneys. A reduced concentration ability was found almost entirely in hydronephrosis complicated with upper urinary tract infection or renal calculi. Hydronephrotic kidneys without these complications showed a normal concentration ability in 10 of 11 cases. Parenchymal function was reduced in only 10 hydronephrotic kidneys, 7 of which had had upper urinary tract infections and 3 of which had renal stones. It is our opinion that uncomplicated cases of unilateral hydronephrosis should not be operated upon unless necessitated by signs and symptoms. Measurement of the maximum urinary concentration ability might be helpful in setting the correct indication for surgery in borderline cases.
Cyclic AMP, renal function and dihydralazine-stimulated renin secretion in hypertensive patients.
The concentrations of plasma cAMP and plasma renin activity were determined in arterial and renal venous plasma in nineteen patients investigated for renin-mediated hypertension. The cAMP measurements were performed in two different situations (1) under basal conditions and (2) after i.v. dihydralazine administration, a potent renin stimulation procedure. Thirteen patients had a lateralization of the renin secretion in the basal state and the administration of dihydralazine caused a further marked renin-secretion. The cAMP concentration was higher in the renal veins draining renin-positive kidneys than in the contralateral renal veins. No significant change was observed between the arterial cAMP concentration and the cAMP concentration in either of the renal veins during dihydralazine-stimulated renin secretion. There was no correlation between the cAMP extraction and the renin secretion of the individual kidneys, but the cAMP extraction correlated with the extraction ratio of PAH. These results show that cAMP values are mainly influenced by the renal function and are not related to the state of renin secretion. Increased cAMP levels in renovascular patients and urameic patients are therefore mainly due to defective elimination of the nucleotide by the kidneys.
Effect of Sar1-ala8-angiotensin II on blood pressure and renin in Bartter's syndrome, before and after treatment with prostaglandin synthetase inhibitors.
Three patients suffering from Bartter's syndrome were studied before and after 5 days of treatment with the prostaglandin synthetase inhibitors, aspirin and indomethacin. Saralasin was given by intravenous infusion in increasing doses from 0.6 to 42 micrograms/min.kg/BW. During saralasin infusion a blood pressure reduction was observed in all patients. Aspirin treatment did not affect this response and nor did it affect other manifestations of the syndrome. Indomethacin treatment changed the blood pressure response to saralasin in such a way that the blood pressure was increased in one patient and was unchanged in the other. Indomethacin also tended to normalize other features of Bartter's syndrome, such as the hyperreninaemia and angiotensin unresponsiveness, but did not affect the hypokalaemia. The saralsin effect on blood pressure is thus evidently inversely related to the prevailing activity of the renin-angiotensin system in this condition also, and the patients obviously depended on the renin-angiotensin system to maintain their blood pressure. Our findings, together with data in the literature, indicate that angiotensin unresponsiveness of the vascular bed is not a primary feature in Bartter's syndrome. Chloride loss is currently thought to be the basic abnormality and this may link the Bartter's syndrome with other diseased states characterized by chloride loss, such as the syndrome of habitual vomiting and chronic treatment with loop diuretics.
Urinary concentration test with desmopressin.
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Renal extraction of p-aminohippurate: physiological and clinical observations.
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Diuretic urography and renography in the diagnosis of hydronephrosis.
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Observations on the use and limitations of renal vein renins in hypertensive patients.
From our consecutive series of renal vein renin studies in 170 patients with kidney disorders and hypertension, we present those cured by surgical correction of a unilateral renal artery stenosis during the period 1973--75. The renin secretion patterns of these patients range between no demonstrable abnormality, even with a stimulating procedure using dihydralazine 7.5 i.v., and massive renin secretion already during basal conditions. Thus, the renin secretion may not be increased even after stimulation in some patients with durable unilateral renovascular hypertension. This fact may be explained by the rise of the systemic blood pressure, eventually maintained by sodium and water retention and accompanied by adaptive changes in the contralateral kidney. The perfusion pressure is thereby kept normal in the affected kidney, eliminating a stimulus for renin secretion. It is likely that many cases of renovascular hypertension pass through an early stage where no involvement of the renin-angiotensin system may be discovered. Of course, these patients will also benefit from surgery. The conclusion is that renin studies for diagnostic purposes should be performed when patients are on treatment and kept normotensive for some time, and that an additional challenge of the perfusion pressure, i.e., by use of dihydralazine, intravenously should be performed.
Determination of glomerular filtration rate in advanced renal insufficiency.
The glomerular filtration rate (GFR) has been determined in 17 patients with advanced renal insufficiency (GFR less than 15 ml/min) by different clearance techniques using creatinine, inulin and 51Cr-EDTA as filtration markers. With renal inulin clearance as reference method for GFR, endogenous renal creatinine clearance overestimated GFR by an average of 30%. Renal clearance of 51Cr-EDTA and inulin were closely correlated and thus 51Cr-EDTA is a suitable GFR marker even at low filtration rates. However, it was found that the plasma clearance of 51Cr-EDTA overestimated the GFR often by more than 100% in the range 2.6--11.2 ml/min. Renal clearance measured during 24 h was lower than 4 h renal clearance with the patient well hydrated and resting in bed. It is concluded that the precise measurement of low glomerular filtration rates requires the use of renal clearance techniques. Four-hour 51Cr-EDTA renal clearance is a suitable method for measuring and following the development of renal function in advanced renal insufficiency.
Renin-dependent hypertension in patients with unilateral kidney disease not caused by renal artery stenosis.
The practical value of renin secretion studies in hypertension associated with unilateral kidney disease, other than renal artery stenosis, has not been documented. This study, comprising 19 patients of this kind, disclosed three who had an abnormal renin secretion from the diseased kidney. The level of peripheral renin under basal conditions, and the change from this level as a result of provocation of renin secretion, were used to evaluate the importance of an arteriovenous renin gradient in the diseased kidney. The three patients were the only ones to become normotensive when the diseased kidney was removed in seven of the cases studied. When nephrectomy is considered in severe hypertension with unilateral kidney disease, there is a place for renin secretion studies, but a screening procedure is advisable. Measuring peripheral renin under basal conditions and after provocation of renin secretion, should reveal whether the renin-angiotensin system might be playing a part in maintaining the high BP. The finding of diminishing kidney function in many of the patients, despite good BP control, emphasizes the importance of sparing kidney function whenever possible.
Renal function in patients with hydronephrosis.
The glomerular filtration rate and pelvic drainage function were reinvestigated after 3-5 years in 50 patients with hydronephrosis secondary to functional obstruction in the pelvic-ureteric junction. Pyeloplasty by the Anderson-Hynes' technique had been performed in 28 kidneys, while 12 patients were not operated upon and 10 had had a nephrectomy. The glomerular filtration rate was determined with the clearance technique and isotope renography. 16 out of 28 kidneys subjected to pyeloplasty and 11/12 non-operated kidneys had a normal renal parenchymal function at the first investigation in spite of severely disturbed drainage function. In the non-operated series the renal parenchymal function was unchanged in 11 patients. Deterioration was observed in 1 kidney, probably because of chronic pyelonephritis. Uncomplicated cases of pelvic-ureteric junction obstruction should not be operated upon unless necessitated by symptoms. A yearly control programme including a renal function test and plain films of the upper urinary tract is recommended for these patients.
[The renin-angiotensin system in normal and hypertensive individuals].
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Renal function in normo- and hypertensive 50-year-old males.
Renal function, measure as glomerular filtration rate (GFR), sodium excretion and osmolality after thirst, has been determined in untreated (n=35) and treated (n=22) hypertensives and in a reference group (n=80), all derived from a random population sample of 50-year-old men. Renal function was related to casual and resting BP and to relative body weight. Hypertension was defined as SBP greater than 175 or DBP greater than 115 mmHg on two separate occasions or current antihypertensive treatment. Mean GFR was 100 +/- 11.7 ml/min in the reference group and significantly lower, 94 +/- 15.7 ml/min, in the hypertension group. In the hypertension group, 20% had a reduced GFR, although the standard diagnostic procedure, serum creatinine, demonstrated only 4%. Hypertensives with reduced GFR were characterized by higher BP, lower urinary sodium excretion, reversed diurnal rhythm of salt and water excretion and a higher relative body weight, which was, however, explained by the correlation of BP to relative body weight. GFR was negatively correlated to DBP at rest and positively correlated to urinary sodium excretion. Untreated hypertensives with persistent high BP after rest and lower GFR, lower urinary sodium excretion and reversed diurnal rhythm of salt and water excretion, indicating high renal resistance. The results suggest that subjects with relatively severe hypertension as judged by BP and renal function have an increased renal vascular resistance.
Plasma renin activity and hypertensive organ manifestations in 50-year-old males.
From a screening examination in a randomly selected third of the 50-year-old male population in Göteborg, Sweden, a 10% subsample was selected as a reference group (n=80). All untreated persons with SBP greater than 175 or DBP greater than 115 mmHg on two separate occasions made up the hypertension group (n=35). The reference group and the hypertension group were subjected to the same investigations, including BP measurement before and after rest and determination of plasma renin activity (PRA), urinary sodium and norepinephrine excretion and GFR. Plasma renin activity was approximately normally distributed in both the reference and the hypertension group. Mean values were 0.78 +/- 0.18 and 0.65 +/- 0.17 ng/ml/h respectively, the difference being almost statistically significant (0.10 greater than p greater than 0.05). There was no difference with respect to sodium excretion between the reference group and the hypertension group. In the reference group, heart rate was positively correlated to PRA and to urinary norepinephrine excretion during the day. No linear correlation between PAR and BP was found, either in the reference group, or in the hypertension group. Sodium excretion during the day was positively correlated to GFR in the hypertension group, but not in the reference group. Compared to hypertensives with normal or high sodium excretion during the day, the hypertensives with low sodium excretion during the day were characterized by a higher BP, a lower GFR and a reversed diurnal rhythm of urine excretion. Thus, low sodium excretion seemed to indicate more severe hypertension with increased renal resistance during the day. The hypertension group was also divided with regard to sodium excretion into a low, normal and high renin group. The low renin group had the lowest GFR and with rising renin group (from low via normal to high) there was a significant increase in GFR and a significant decrease in resting BP. The results indicate that low renin hypertension is not a more mild, but indeed rather a more severe form of hypertension.