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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 18 (1980), S. 135-139 
    ISSN: 1432-1041
    Keywords: hypertension ; labetalol ; propranolol ; renal haemodynamics ; glomerular filtration rate ; blood pressure ; exercise ; renal blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of exercise on renal haemodynamics was examined in young patients with mild essential hypertension. Four groups of subjects were studied: 13 normotensive, healthy control subjects, and 15 untreated, 11 propranolol-treated, and 6 labetalol-treated patients. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were measured during four consecutive periods, a pre-exercise control period, two exercise periods with loads of 450 kpm/min and 600 kpm/min, respectively, and a post-exercise control period. In the untreated patients RPF and GFR were lower during exercise than in the normotensive control subjects, whereas no significant differences were found at rest. In the propranolol-treated patients the reduction in RPF and GFR during exercise was more pronounced than in the untreated hypertensives. In the labetalol-treated patients however, RPF and GFR were reduced only to the same degree as in the untreated hypertensives. The reduced renal blood flow in propranolol-treated patients may be attributed to a compensatory increase in sympathetic activity caused by an impaired cardiac response to exercise. The lack of reduction in renal blood flow during labetalol therapy could partly be related to alpha-adrenergic blockade in the renal vascular bed induced by labetalol, and partly to the smaller reduction in cardiac output during labetalol than during propranolol therapy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-1803
    Keywords: Na,K-ATPase ; 3H-ouabain binding ; heart failure ; tachycardia ; potassium ; calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The present study evaluates3H-ouabain binding site (Na,K-ATPase) concentration in left ventricular myocardium of dogs with heart failure induced by tachycardia as a result of ventricular pacing. Samples of left ventricle were obtained from 10 dogs exposed to pacing of 240 beats/min for 3 to 4 weeks and eight sham-operated controls. Na,K-ATPase was quantified using vanadate facilitated3H-ouabain binding to intact samples. At time of sacrifice paced dogs showed clinical signs of heart failure, a significant 257% increase in left ventricular end diastolic pressure and a significant 46% decrease in left ventricular dP/dt compared with control. There was no significant change in left ventricular mass.3H-ouabain binding concentration was significantly reduced by 16%. Evaluation of3H-ouabain binding kinetics revealed no significant difference between myocardium from paced and control dogs: Equilibrium binding conditions were at the various concentrations used obtained after similar incubation time; nonspecific uptake and retention of3H-ouabain was 0.9–0.8% of total uptake and retention obtained in the standard assay; apparent dissociation constant (KD) was 6.5×10−8–6.6×10−8mol/l; loss of specifically bound3H-ouabain during washout at 0°C occurred with a half-life time (T3/2) of 120 and 121h. Hence, total3H-ouabain binding site concentration in left ventricular myocardium was (mean±SEM) 1110±56 and 1317±68 pmol/g wet weight, 8.54±0.43 and 10.05±0.52 pmol/mg protein, and the total amount of3H-ouabain binding sites in the entire left ventricle 121±6 and 162±8 nmol in paced (n=10) and control (n=8) dogs (p〈0.05), respectively. In conclusion, the present study reports a significant reduction in left ventricular myocardium3H-ouabain binding site concentration in tachycardia induced heart failure. This observation supports the concept of a relationship between Na,K-ATPase concentration and contractile capacity and may be of pathophysiological importance in tachycardia and heart failure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Basic research in cardiology 90 (1995), S. 323-331 
    ISSN: 1435-1803
    Keywords: Na+ ; K+-ATPase ; Ca2+-ATPase ; rat ventricular myocardium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Assays for complete quantification of Na+, K+-and Ca2+-ATPase in crude homogenates of rat ventricular myocardium by determination of K+-and Ca2+-dependentp-nitrophenyl phosphatase (pNPPase) activities were evaluated and optimized. Using these assays the total K+-and Ca2+-dependentpNPPase activities in ventricular myocardium of 11–12 week-old rats were found to be 2.98±0.10 and 0.29±0.02 μmol×min−1×g−1 wet wt. (mean±SEM) (n=5), respectively. Coefficient of variance of interindividual determinations was 7 and 12%, respectively. The total Na+, K+-and Ca2+-ATPase concentrations were estimated to 2 and 10 nmol×g−1 wet wt., respectively. Evaluation of a putative developmental variation revealed a biphasic age-related change in the rat myocardial Ca2+-dependentpNPPase activity with an increase from birth to around the third week of life followed by a decrease. By contrast, the K+-dependentpNPPase activity of the rat myocardium showed a decrease from birth to adulthood. It was excluded that the changes were simple out-come of variations in water and protein content of myocardium. Expressed per heart, the K+-and Ca2+-dependentpNPPase activity gradually increased to a plateau. The present assay for Na+, K+-ATPase quantification has the advantage over [3H] ouabain binding of being applicable on the ouabain-resistant rat myocardium, and is more simple and rapid than measurements of K+-dependent 3-0-methylfluorescein phosphatase (3-0-MFPase) in crude tissue homogenates. Furthermore, with few modifications thepNPPase assay allows quantification of Ca2+-ATPase on crude myocardial homogenates. Age-dependent changes in K+-and Ca2+-dependentpNPPase activities are of developmental interest and indicate the importance of close age match in studies of quantitative aspects of Na+, K+-and Ca2+-ATPase in excitable tissues.
    Type of Medium: Electronic Resource
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