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Biomedical subjects

K Kjeldsen

Publications and source records attributed to K Kjeldsen.

At least 127 records · Page 7Linked to original sources
PubMed1984

A method for the determination of the total number of 3H-ouabain binding sites in biopsies of human skeletal muscle.

A new method based on vanadate facilitated binding of 3H-ouabain has been applied for the quantitative determination of the number of 3H-ouabain binding sites (Na-K-pumps) in needle biopsies of human skeletal muscle. Samples of the vastus lateralis muscle weighing 2-8 mg showed specific and saturable binding of 3H-ouabain with an apparent KD of 1.9 X 10(-8) mol/l. In 20 healthy human subjects in the age range 25-80 years, the number of 3H-ouabain binding sites was 278 +/- 15 pmol/g wet weight with no relation to age or sex. In samples of the intercostal and rectus abdominis muscles, the number of 3H-ouabain binding sites varied from 225 to 280 pmol/g wet weight. These values are at least 2 times higher than those previously reported for human skeletal muscle. The number of 3H-ouabain and 3H-digoxin binding sites were identical, and ouabain (10(-3) mol/l) completely displaced specifically bound 3H-digoxin. When biopsies were frozen in liquid N2 immediately after withdrawal, storage at -20 degrees C for up to 11 weeks caused no significant change in the number of 3H-ouabain binding sites. The method allows quantitative determination of the number of 3H-ouabain binding sites in standard biopsies of human skeletal muscle to be performed by simple procedures within a few hours. This can be used for the study of conditions where the number of Na-K-pumps is known to undergo fluctuations.

Adult↗
PubMed1983

Effects of denervation on sodium, potassium and [3H]ouabain binding in muscles of normal and potassium-depleted rats.

K depletion leads to a selective loss of K from skeletal muscles, which is associated with a decrease in the number of [3H]ouabain binding sites. The significance of the nerve supply for these changes has been assessed in denervation experiments with K-depleted rats. In K-depleted rats (age 4-12 weeks) denervation led to a partial recovery of the K contents in soleus (46-77%), gastrocnemius (23%) and extensor digitorum longus (e.d.l.) muscles (19%) within 24 h. These effects were not prevented by beta-adrenoceptor blockade or mimicked by alpha-adrenoceptor blockade. In K-depleted rats the number of [3H]ouabain binding sites was not increased following denervation. In K-depleted rats 24 h of plaster immobilization of the entire hind limb caused 51% recovery of the total K content in soleus, whereas gastrocnemius and e.d.l. showed 49 and 16% recovery, respectively. Tenotomy for 3 h caused a rise in total K content of 33% in soleus muscles from K-depleted rats. Anaesthesia for 3 h increased the total K content by 23%. The recovery of K induced by denervation, immobilization in plaster, tenotomy or anaesthesia was associated with an equivalent decrease in Na content. Denervation performed before K depletion reduced the loss of K from soleus, but not from gastrocnemius and e.d.l. In both soleus and e.d.l. the number of [3H]ouabain binding sites, however, decreased to the same level as in the contralateral innervated muscles. Denervation reduced, but did not prevent, the increase in the number of [3H]ouabain binding sites seen after re-administration of K to K-depleted rats. It is concluded that the changes in Na-K contents seen after denervation in K-depleted rats are the outcome of cessation of muscle activity. The results give no support to the idea that the effects of K depletion on the K content and the number of [3H]ouabain binding sites in skeletal muscle are mediated by the peripheral nerves.

Animals↗
PubMed1982

Age-dependent changes in the number of [3H]ouabain-binding sites in rat soleus muscle.

The influence of age on the number of (Na+K+)-ATPase units in skeletal muscle has been assessed by measurements of [3H]ouabain binding in vitro and in vivo to rat soleus muscle. In vitro measurements showed that from the 2nd to the 28th day of life, the number of [3H]ouabain-binding sites increases from 120 to 580 pmol/g wet wt. This is followed by a decrease, until a plateau between 150 and 200 pmol/g is reached around 150 days after birth. 60 min after intraperitoneal injection of [3H]ouabain (12.5 mumol/kg body weight), the soleus muscles of 28-day-old rats had accumulated 2.4-times more 3H-activity per g wet wt. than muscles of 85-day-old rats and the 3H-activity in plasma was 54% lower. The results may explain the low sensitivity to digitalis glycosides found in infants as compared to premature or adult individuals.

Aging↗
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

Ultrastructure of the aortic intima in focal areas of intravital Evans blue uptake in the rabbit.

Ultrastructural morphology of the rabbit aortic intima is described for areas demarcated or not demarcated by spontaneous in vivo uptake of the azo dye Evans Blue. Intimal foci taking up Evans Blue are characterized by endothelial and subendothelial cells showing various degrees of degenerative changes, appearance of young cells and subendothelial fibromuscular thickening. It is concluded that dye uptake is a marker for regions subjected to hemodynamic "stress' due to turbulence or increased flow load, and that the morphologic changes in normal animals are part of appropriate regeneration processes which keep the artery functionally intact. Such foci may represent predilection areas for atherogenesis in pathological situations, such as hypertension or hypercholesterolemia.

Animals↗
PubMed1978

Effect of carbon monoxide exposure on aortic and coronary intimal morphology in the rabbit. A revaluation.

Non-cholesterol-fed rabbits were exposed to carbon monoxide at concentrations in air of either 200, 2000, or 4000 parts per million (=0.02, 0.2 or 0.4%, vol/vol). Using the same criteria for intimal damage as in earlier morphological studies, no histotoxic effect on intimal/subintimal morphology of coronary arteries or the aorta could be demonstrated, when light-microscopic evaluation was performed blindly.

Animals↗
PubMed1977

Thrombogenic properties of arterial catheters: a scanning electron microscopic examination of the surface structure.

We performed 300 consecutive coronary arteriographies with 2 different kinds of catheters: polyurethane catheters and polyethylene catheters. The thromboembolic complication rate for investigations with each type of catheters is compared to the surface structure as seen with the scanning electron microscope (SEM). The complication rate was 21.4% for polyurethane catheters and 0.3% for polyethylene catheters. The inner surface of polyurethane catheters was irregular, while the inner surface of polyethylene catheters appeared smooth. The outer surface of polyurethane catheters was slight irregular, while the outer surface of polyethylene catheters was smooth. These results are compared to other investigations of the surface structure of coronary catheters and to reports on the thromboembolic complication rate at coronary arteriography. It is concluded that the 2 types of catheters have different thrombogenic properties and that the surface structure is of major importance for this difference.

Cardiac Catheterization↗