PubMed Health⌕ Search

Biomedical subjects

O Hansen

Publications and source records attributed to O Hansen.

At least 145 records · Page 8Linked to original sources
PubMed1986

Quantification of the 3H-ouabain binding site concentration in human myocardium: a postmortem study.

The 3H-ouabain binding site concentration in the human myocardium was determined by measuring vanadate facilitated binding of 3H-ouabain to necropsy specimens of the left ventricle. The 3H-ouabain binding to samples weighing 4-6 mg was specific and saturable and appeared to take place to only one population of high affinity binding sites. After death the 3H-ouabain binding capacity degraded relatively slowly. From 6 to 24 h after death a mean decrease of 11% was seen in five patients, being significant in only one. In 15 patients aged 64-86 years the concentration of 3H-ouabain binding sites measured 6 h after death varied from 223 to 577 pmol X g-1 wet weight with no obvious relation to age or sex. The mean (SEM) value (413(26) pmol X g-1 wet weight) was 1.7 times higher than that previously reported for human myocardium. The concentrations of 3H-ouabain and 3H-digoxin binding sites were identical, and an excess of unlabelled ouabain completely prevented the specific binding of 3H-digoxin. In necropsy specimens weighing 1-2 mg from the endomyocardium obtained using a biotome the 3H-ouabain binding site concentration was in the same range as that in the myocardium. These findings indicate that it is possible to determine the concentration of Na, K-pumps in the human myocardium by measuring the 3H-ouabain binding capacity of biopsy specimens obtained during heart catheterisation or of specimens obtained within the first 18 h after death. This finding may be of importance for studying conditions in which the Na, K-pump concentration is suspected of undergoing variation.

Aged↗
PubMed1985

K+-dependent 3-O-methylfluorescein phosphatase activity in crude homogenate of rodent heart ventricle: effect of K+ depletion and changes in thyroid status.

The total Na+-K+-ATPase activity in rodent heart ventricle was quantified by determination of K+-dependent, ouabain suppressible 3-O-methylfluorescein phosphatase activity. A K+-dependent phosphatase activity of 0.80 mumol/min per g wet wt was obtained from crude homogenate of heart ventricle from 4-week-old guinea pigs. The anticipated association between K+-dependent phosphatase activity and Na+-K+-activated ATP hydrolysis could be clearly demonstrated in the crude homogenate. Based upon a molecular activity of 550/min the corresponding cardiac glycoside receptor concentration in the crude homogenate was 1450 pmol/g wet wt. In crude homogenate of heart ventricle from 3-month-old rats the K+-dependent phosphatase activity was 1.16 mumol/min per g wet wt. Following 4 weeks of K+ depletion of the rats, a decrease of 13% in total K+ content of the heart ventricle was seen. This was associated with a 14% decrease in K+-dependent phosphatase activity. The induction of hypo- and hyperthyroidism for 3 weeks in rats was followed by a decrease of 27% and an increase of 13% in K+-dependent phosphatase activity, respectively.

Animals↗
PubMed1985

Significance of skeletal muscle digitalis receptors for [3H]ouabain distribution in the guinea pig.

The importance of specific digitalis glycoside binding sites in skeletal muscle for the digitalis glycoside distribution in the guinea pig was evaluated using [3H]ouabain and [3H]digoxin binding assays. Measurements of [3H]ouabain binding capacity (EOmax) in gastrocnemius and heart muscles in vitro gave values of 474 +/- 15 and 1,092 +/- 39 pmol/g wet wt., respectively, in 4-week-old guinea pigs. Hence the total amount of [3H]ouabain binding sites in skeletal muscle and the heart was around 42,700 and 1,200 pmol, respectively. The apparent dissociation constants (Kd) for ouabain receptor interaction was 0.7 X 10(-7) and 1.5 X 10(-7) M for skeletal muscle and heart, respectively. Comparison of [3H]ouabain and [3H]digoxin binding revealed that these drugs are competitive. From birth to maturity the concentration of [3H]ouabain binding sites in guinea pigs decreased from 803 +/- 58 to 304 +/- 28 pmol/g wet wt. in gastrocnemius muscle and from 1,458 +/- 31 to 1,079 +/- 19 pmol/g wet wt. in the heart. After i.p. injection, measurements of the distribution of [3H]ouabain in plasma, skeletal muscle and the heart showed an almost equal relative specific occupancy of digitalis glycoside receptors in skeletal muscle and the heart: When 10% of the digitalis receptors in the heart were occupied by [3H]ouabain, 13% of those in the skeletal muscles were occupied. It was calculated that 1 hr after the i.p. administration of [3H]ouabain the amount of [3H]ouabain specifically bound to the skeletal muscles and the heart corresponded to 5 times and 1/10 the amount available in the extracellular pool, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1984

(Na+ + K+)-ATPase activity of crude homogenates of rat skeletal muscle as estimated from their K+-dependent 3-O-methylfluorescein phosphatase activity.

A highly sensitive fluorimetric assay using 3-O-methylfluorescein phosphate as substrate was used in the determination of K+-dependent phosphatase activity in preparations of rat skeletal muscle. The gastrocnemius muscle was chosen because of mixed fibre composition. Crude, detergent treated homogenate was used so as to avoid loss of activity during purification. K+-dependent phosphatase activities in the range 0.19-0.37 mumol X (g wet weight)-1 X min-1 were obtained, the value decreasing with age and K+-deficiency. Complete inhibition of the K+-dependent phosphatase was obtained with 10(-3) M ouabain. Using a KSCN-extracted muscle enzyme the intimate relation between K+-dependent phosphatase activity and (Na+ + K+)-activated ATP hydrolysis could be demonstrated. A molecular activity of 620 min-1 was estimated from simultaneous determination of K+-dependent phosphatase activity and [3H]ouabain binding capacity using the partially purified enzyme preparation. The corresponding enzyme concentration in the crude homogenates was calculated and corresponded well with the number of [3H]ouabain binding sites measured in intact muscles or biopsies hereof.

Animals↗
PubMed1983

Heterotopic ossification of the intestinal mesentery. Report of a case following intraabdominal surgery.

In a 55-year-old male a nodular mass of heterotopic ossification developed in the intestinal mesentery two weeks after coloproctectomy for severe ulcerative colitis. The lesion was located close to the ileostoma where it encroached upon the intestinal wall and led to luminal obstruction. Histological examination of the tumour mass showed actively proliferating mesenchymal cells forming irregular areas of primitive osteoid and bone. The process appeared consistent with an early stage of heterotopic ossification where the short history explains the absence of the "zone phenomenon" usually characterizing such lesions. By reviewing the literature the reported case appears unique as other cases of intraabdominal heterotopic ossification have not been encountered.

Colitis, Ulcerative↗
PubMed1982

Studies on ouabain-complexed (Na+ +K+)-ATPase carried out with vanadate.

Vanadate is able to promote the binding of ouabain to (Na+ +K+)-ATPase and it is shown that vanadate is trapped in the enzyme-ouabain complex. Also ouabain-bound enzyme, the formation of which was facilitated by (Mg2+ +Na+ +ATP) or (Mg2+ +Pi), is accessible to vanadate when washed free of competing ligands used for the promotion of ouabain binding. For vanadate binding to (Na+ +K+)-ATPase and to enzyme-ouabain complexes a divalent cation (Mg2+ or Mn2+) is indispensable, indicating that the cation does not remain attached to the ouabain-bound enzyme. K+ further increases vanadate binding in the absence of ouabain, but seems to have no additional role in case of vanadate binding to enzyme-ouabain complexes. Mn2+ is more efficient than Mg2+ in promoting binding of vanadate and ouabain to (Na+ +K+)-ATPase. That K+ in combination with Mn2+, in analogy with the effect in combination with Mg2+, increases the equilibrium binding level of vanadate and decreases that of ouabain does not seem to favour the hypothesis of selection of a special E2-subconformation by Mn2+. The vanadate-trapped enzyme-ouabain complex was examined for simultaneous nucleotide binding which could demonstrate a two-substrate mechanism per functional unit of the enzyme. The acceleration by (Na+ +ATP) of ouabain release from the (Mg2+ +Pi)-facilitated enzyme-ouabain complex does not, as anticipated, support such a mechanism. On the other hand, the deceleration of vanadate release as well as of ouabain release from a (Mg2+ +vanadate)-promoted complex could be consistent with a two-substrate mechanism working out-of-phase.

Animals↗
PubMed1982

Effect of age, potassium depletion and denervation on specific displaceable [3H]ouabain binding in rat skeletal muscle in vivo.

1. Following intraperitoneal injection of [(3)H]ouabain in rats, the isotope is rapidly distributed in blood plasma available for binding to the Na-K-ATPase in the plasma membranes of most tissues. In skeletal muscle tissue excised and washed 4 x 30 min in ice-cold buffer, 95% of the (3)H activity retained was shown to be [(3)H]ouabain using a specific binding assay.2. The [(3)H]ouabain bound to soleus and extensor digitorum longus (e.d.l.) muscles in vivo and retained following wash-out in the cold showed the same saturation characteristics as those determined when binding took place in vitro.3. In soleus and e.d.l. muscles obtained from 28-day-old rats, the number of [(3)H]ouabain binding sites measured in vivo was 583+/-19 and 720+/-22 pmol/g wet wt., respectively, i.e. in good agreement with previous and present results obtained in vitro.4. In vivo measurements showed that 7 days after denervation, the number of [(3)H]ouabain binding sites in soleus and e.d.l. muscles was reduced by 22 and 13%, respectively.5. In the age interval from 28 to 85 days, the number of [(3)H]ouabain binding sites in soleus was found to decrease by 58%. Following I.P. injection of [(3)H]ouabain, the 85-day-old rats showed a more pronounced and sustained rise in plasma (3)H activity, which in part can be due to the reduced capacity for [(3)H]ouabain binding in skeletal muscle.6. K depletion induced by the administration of K-deficient diet for 3 weeks reduced [(3)H]ouabain binding by 63% in soleus muscles. In the K-depleted animals, the plasma (3)H activity measured 15 min after I.P. injection of [(3)H]ouabain was 77% higher than in controls receiving the same dose per kg body weight.7. The present in vivo results provide further support for the idea that increased digitalis toxicity due to increasing age or K depletion is related to reduced binding capacity for digitalis glycosides in skeletal muscle.

Aging↗
PubMed1981

Sympathetic nerve terminal destruction has no effect on specific [3H]ouabain binding to intact mouse and rat skeletal muscle.

Following pretreatment with 6-OH-dopamine, the sympathetic nerve endings of the iris and skeletal muscle of mice and rats were not longer detectable by cytochemistry for noradrenaline. In the same animals, the specific binding of [3H] ouabain to intact soleus muscles was not significantly different from that measured in controls, Neither ouabain-suppressible 42K uptake nor Na-K contents were affected by chemical sympathectomy.

Animals↗
PubMed1980

Soluble immune complexes in cerebrospinal fluid of patients with multiple sclerosis and other neurological diseases.

The occurrence of soluble immune complexes (IC) in the cerebrospinal fluid (CSF) of 14 multiple sclerosis (MS) patients, four acute polyradiculoneuritis patients, 30 patients with other neurological diseases (OND) and 30 patients with disc prolapse (DP) was examined by a solid phase C1q-protein A binding assay (C1q-PABA) and a complement consumption test. IC-positive reactions were observed only in the C1q-PABA. The binding indices determined by the C1q-PABA differed significantly (P < 0.01) when the MS or the OND patient groups were compared to the DP group. No significant (P < 0.1) difference was observed between the indices in the MS and OND groups. Binding indices in C1q-PABA showed no correlation either to IgG concentration, total protein concentration or cell counts in CSF of MS patients. Three of the four polyradiculoneuritis patients were strongly IC-positive while the fourth patient was negative. Filtration and PEG-precipitation data indicated that a major part of the IgG-containing IC in CSF detected by C1q-PABA was of macromolecular nature.

Adolescent↗