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Biomedical subjects

M Stimpel

Publications and source records attributed to M Stimpel.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Plasma levels of atrial natriuretic peptide (ANP) in patients with paroxysmal supraventricular tachycardia and concomitant polyuria (urina spastica)].

A concomitant diuresis and natriuresis has been reported to occur in 30-50% of patients with paroxysmal supraventricular tachycardia. While the increase of the diuresis may be secondary to an inhibition of vasopressin, the etiology of the natriuresis is presently not well understood. To determine the role of atrial natriuretic peptide (ANP) in the pathogenesis of tachycardia-induced polyuria, we measured ANP levels in two female patients (aged 59 and 68 years) with recurrent episodes of paroxysmal supraventricular tachycardia during such attacks, as well as after conversion to a normal sinus rhythm. In both patients, episodes of supraventricular tachycardia were associated with both a large increase in ANP plasma levels (560 resp. 1.208 pg/ml; normal range: 50 +/- 10 pg/ml) and polyuria. Despite elevated ANP plasma levels, no diuretic and natriuretic response to tachycardia could be observed during episodes of shorter duration, some of which occurred in the older patient studied. After restoration of a normal sinus rhythm, ANP plasma levels decreased to baseline levels (107 resp. 32 pg/ml). The results of this study show that the secretion of ANP is increased during episodes of paroxysmal supraventricular tachycardia, suggesting that ANP might contribute to the pathogenesis of natriuresis and diuresis frequently associated with supraventricular tachycardia.

Aged↗
PubMed1988

[Atrial natriuretic peptide (ANP) in essential hypertension: a humoral marker for salt sensitivity and hypertensive heart disease at a clinically asymptomatic stage?].

Out of 32 patients (f = 10, m = 22; mean age: 46 +/- 3 years) with untreated essential (primary) hypertension (WHO-classification I-III) and without clinical signs of congestive heart failure or chronic renal failure, 19 showed plasma-ANP base levels above the normal range (greater than 100 pg/ml; normal range: 50 +/- 10 pg/ml). While high sodium loading caused an increase of plasma ANP levels and a concomitant decrease of plasma renin and aldosterone concentrations, low sodium loading caused the opposite pattern of ANP and renin/aldosterone secretion. Some patients with essential hypertension with highly elevated plasma ANP levels (10-20-fold above the normal range) showed an only moderate decrease of ANP and a slight increase of renin under a low sodium diet. Plasma ANP levels were significantly correlated with the heart volume (r = 0.54; p less than 0.05; radiologically determined), the electrocardiographic signs of left ventricular hypertrophy (Sokolow-Lyon index; r = 0.62; p less than 0.05) and with the left atrial diameter (r = 0.34; p less than 0.05; determined by 2-D-echocardiography). We speculate that high levels of plasma ANP in patients with essential hypertension might be interpreted as a compensatory mechanism either for an insufficient excretion of sodium or for myocardial dysfunction.

Adult↗
PubMed1987

Studies of pharmacokinetics and therapeutic effects of glucocorticoids entrapped in liposomes after intraarticular application in healthy rabbits and in rabbits with antigen-induced arthritis.

Dexamethasone palmitate (DMP) entrapped in liposomes of defined sizes was administered intraarticularly in healthy rabbits and in rabbits with antigen-induced arthritis. The pharmacokinetics and therapeutic effect of liposomal DMP were measured and compared with corresponding experiments using microcrystalline triamcinolone acetonide (TAC). The small DMP liposomes (diameter 160 nm) showed a greater decrease in joint circumference than the 3-times-higher dose of microcrystalline TAC. Moreover, about 98% of administered TAC had already disappeared from the joint 6 h after injection, whereas about 36% of liposomal DMP was still measured in synovial fluid and synovium at the same time. Increasing the vesicle diameter from 160 to 750 nm (large liposomes) improved the retention of DMP by a factor of 2.6 within 48 h after injection in healthy rabbits. In addition, none of the liposomal glucocorticoid preparations ever suppressed the endogenous plasma cortisol level, which is in contrast to the suppression measured after administration of the microcrystalline preparation.

Animals↗
PubMed1986

Effect of atrial natriuretic polypeptide on angiotensin II-induced increase of cytosolic free calcium in cultured smooth muscle cells.

We investigated the effects of angiotensin II (ANG II) and synthetic atrial natriuretic polypeptide (ANP) on cytosolic free calcium concentration [( Ca2+]i) of cultured rat vascular smooth muscle cells. Incubation with ANP alone showed little or no change in [Ca2+]i, whereas ANG II alone increased [Ca2+]i in a dose-dependent manner up to 164%, compared with basal levels of 253 +/- 17 nmol/l (mean +/- s.e.m.). Simultaneous addition of 10 nmol/l ANG II and varying concentrations of ANP produced a reduction in the ANG II-induced increase in [Ca2+]i. These data suggest that the vasorelaxant effect of ANP is at least partly mediated by changes in [Ca2+]i.

Angiotensin II↗
PubMed1985

Captopril before and after spironolactone therapy in primary aldosteronism. Pathogenetic and therapeutical aspects.

In three patients with primary aldosteronism, the acute effect of a single dose of captopril on the elevated mean arterial blood pressure (MAP) was studied before and after 4 weeks of treatment with spironolactone. Before spironolactone therapy, captopril did not cause any drop in MAP. Four weeks later, after an oral daily dose of 400 mg spironolactone, MAP was still elevated in all three patients, though electrolyte abnormalities were fully corrected. Since plasma renin activity (PRA) was increased to values above the normal range, the acute effect of captopril on MAP was tested again. A single dose of 25 mg captopril then caused a fall in MAP to normal. These data reveal the conversion from a renin-independent to a renin-dependent kind of hypertension after spironolactone therapy in three patients with primary aldosteronism syndrome. This might be of pathogenetic and therapeutic interest.

Aldosterone↗
PubMed1985

Stereospecific modulation of the calcium channel in human erythrocytes by cholesterol and its oxidized derivatives.

To study the effect of cholesterol and its pathophysiologically important oxidized derivatives (OSC) on the calcium entry channel, the human red blood cell was used as a model system. The calcium ejecting adenosinetriphosphatase (ATPase) was inhibited by vanadate. The cells were loaded with OSC at concentrations between 1.25 X 10(-5) and 25 X 10(-5) mol/l. 22-Hydroxycholesterol, cholestan-3 beta,5 alpha,6 beta-triol, 5 alpha-cholestan-3 beta-ol,3 beta,5 alpha-dihydroxycholestan-6-one and 3 beta-hydroxy-5 alpha-cholestan-7-one stimulated 45Ca2+ influx by up to almost 90%, whereas 25-hydroxycholesterol, 7 beta-hydroxycholesterol, 20 alpha-hydroxycholesterol and 7-oxocholesterol inhibited influx by up to 75%. Both stimulation and inhibition were dependent on the amount of OSC incorporated into the membrane. More than 90% of the total modification of calcium influx by OSC was accounted for by an influence on the nitrendipine-inhibitable part of influx. Enrichment of cholesterol in the membrane greatly stimulated, and cholesterol depletion inhibited, Ca2+ influx. These results demonstrate that cholesterol and its oxidized derivatives are able to modulate the calcium channel in human red blood cells in a highly stereospecific manner.

Calcium↗