Biomedical subjects

J Kapitola

Publications and source records attributed to J Kapitola.

At least 37 records · Page 2Linked to original sources

PubMed1995

Inhibitory effect of hydrocortisone on the blood flow and 45Ca and 3H-proline incorporation into bones of female rats.

We studied the effects of hydrocortisone as a possible regulatory factor of bone blood flow and metabolism. Local bone blood flow in the tibia, distal femur, lumbar vertebra and some soft tissues (using 85Sr-microspheres), as well as 45Ca and 3H-proline incorporation into the tibia, bone density and ash weight per ml of the tibia were measured in sham-operated and oophorectomized female rats in which the influence of hydrocortisone administration (0.004% diet for 5 weeks) was followed. Hydrocortisone markedly lowered 85Sr-microsphere uptake and blood flow through the bones of non-castrated female rats as well as elevated circulatory values in oophorectomized rats. The changes were nearly identical in the three bone samples measured; among the soft tissues only the kidneys showed a less pronounced decrease. Circulatory changes in the bones seem to be caused by local vascular reactions. Hydrocortisone also lowered the 24-hour incorporation of 45Ca and 3H-proline into the tibia of both non-castrated and oophorectomized females. In the tibia of oophorectomized rats, hydrocortisone normalized the decreased bone density and ash weight. The adrenocortical hormones are known to block eicosanoid synthesis by the inhibition of arachidonic acid production. It is possible, therefore, that local circulatory changes in the bones of rats, induced by hydrocortisone, are mediated by the changes in prostaglandin production.

Animals↗

PubMed1994

Possible participation of prostaglandins in the increase in the bone blood flow in oophorectomized female rats.

The aim of this study was to verify the possible role of prostaglandin (PG) in the increase in the bone blood flow of female rats after oophorectomy (OOX). In two experiments we determined blood flow in the tibia and distal femur (85Sr-microspheres) and 24-h incorporation of 45Ca and 3H-proline. Acetylosalicyclic acid (ASA, 0.13% in the food for 4 weeks) was used to suppress the production of PG. There was an increase in the bone blood flow after OOX (performed 4 weeks prior to the experiment), no change after ASA alone and significant reduction by ASA of the OOX-induced increase in the bone blood flow. In both groups of OOX females there was a decrease in tibial bone density and ash weight. The changes in 45Ca incorporation were similar to those in the blood flow while the changes in 3H-proline incorporation were not significant. Thus, the effect of ASA, i.e. suppression of the OOX-induced increase in the bone blood flow, is consistent with the possible role of PG (probably PGE2) in the increase in bone blood flow of OOX female rats.

Animals↗

PubMed1994

Relationships between local circulatory changes in the tibia and kidney of male and female rats after castration and administration of estradiol or testosterone.

The effects of castration and of the four weeks' administration of estradiol or testosterone on the blood circulation in the tibia and the kidney (expressed as the 85Sr-microsphere uptake values, which are not influenced by simultaneous changes in cardiac output) were studied in four experiments on a total of 147 rats (68 females, 79 males), relative weights being noted at the same time. 85Sr-microsphere uptake in the tibia rose markedly after castration in both males and females, fell after estradiol benzoate in intact females and intact and orchidectomized males and also fell after testosterone in intact and oophorectomized females and orchidectomized males. 85Sr-microsphere uptake in the kidney rose after castration only in males in experiments B; it fell after estradiol in orchidectomized males and fell after testosterone in intact females and males and in orchidectomized males. Relative tibial weight fell in castrated females, but in castrated males only in experiment D; after estradiol it rose only in males (intact and orchidectomized) and rose after testosterone in intact and oophorectomized females and orchidectomized males. Relative kidney weight fell after castration in both males and females, rose after estradiol in intact females and intact and orchidectomized males and rose after testosterone in intact and castrated males and females. In all four experiments there was a demonstrable statistically significant correlation between the 85Sr-microsphere uptake values in the tibia and the kidney. The relative weights displayed a similar correlation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

[The effect of estradiol, norethisterone and testosterone on regional circulation and relative weight of the testes, ovaries and uterus in rats].

In nine experiments of 188 rats (85 males and 103 females), relative weight and local blood flow (with 85Sr-microspheres) was estimated in testes, ovaries and uterus after the administration of estradiol benzoate (Agofollin Depot 1 mg per rat or 5 mg per kg s.c. in time intervals of 3 to 7 days), norethisterone (Norethisterone tablets 0.01 or 0.02% in the food) or testosterone (Agovirin Depot 25 mg per kg s.c. every 5 days); all preparations were administered for four weeks. With one exception (norethisterone in males), the results of two experiments performed in the same manner are presented in every experimental situation. After estradiol, the body weight of rats in both sexes is lowered, relative weight of the uterus increased. The local circulatory indicators i.e. 85Sr-microsphere uptake in % dose per g, blood flow in (ml.min-1).g-1 and organ flow fraction % of cardiac output are decreased in the testes and unchanged on the ovaries. As regards the uterus, in the first experiment the 85Sr-microsphere uptake and the blood flow is significantly lower, in the second experiment these values remain unchanged and flow fraction is increased due to enlargement of the uterus. Norethisterone lowers the body weight and relative weight of the testes; in one experiment it increases relative weight of the uterus. Local circulatory indicators are decreased in the testes and inconstantly in the ovaries, whereas in the uterus the decreases are insignificant. Testosterone does not change the body weight. In one experiment, it increases the cardiac output per 100g of body weight; relative weight of the testes is lowered in one experiment and in the ovaries in both experiments, and markedly increased in the uterus. Local circulatory indicators were decreased in the testes, ovaries and uterus but approximately one half of the differences are significant. Thus, with one exception, all statistically significant local circulatory changes after the administration of the hormonal preparations are decreasing; the suppressive action is evident in the local circulation in sexual organs of the animals of the corresponding sex as well as in animals of the other sex. The suppression of the local circulation in testes and ovaries is probably in connection with endocrine regulations; the decrease of microsphere uptake and blood flow per g in the uterus may participate in insufficient adaptation of the blood supply in the enlargement of the uterus after four weeks' administration of estradiol and testosterone.

Animals↗

PubMed1993

[Local blood circulation and bone mineral content in the bones of rats: the effect of castration, estradiol and testosterone in male and female rats].

Four experiments on 76 female and 79 male rats were performed in which we followed up the effect of four weeks' administration of estradiol benzoate (Agofollin Depot 1 mg per rat once a week or 5 mg per kg once every 5 days s. c.) and testosterone isobutyrate (Agovirin Depot 25 mg per kg once every 5 days s. c.) on the local circulation in the tibia and distal femur (by means of 85 Sr-microsphere uptake) and on bone density and ash weight related to bone volume. Local circulatory values increase in the bones after oophorectomy (OOX) and orchidectomy (ORX) and decrease after estradiol in sham-operated rats of both sexes; testosterone inconstantly reduces the 85Sr-microsphere uptake in the bones of sham-operated male rats. Estradiol decreases local circulatory values in OOX females and ORX males to the level observed in sham-operated animals. Testosterone has a similar inhibitory effect in ORX males as estradiol; less pronounced, but statistically significant lowering occurs also in the tibia of OOX females. Density of the tibia and ash weight related to bone volume unit falls after OOX and ORX and rises constantly after estradiol; after testosterone administration, it does not change in sham-operated rats and OOX females, but rises in ORX males. Probably the most important finding is that also testosterone reduces local circulation in the bones of rats, though less regularly and less markedly than estradiol (in the dosage used).

Animals↗

PubMed1993

[Local blood circulation, uptake of 45Ca, 85Sr and 3H-proline and mineral levels in the tibia of female rats: comparison and changes after administration of estradiol].

After six weeks' administration of estradiol benzoate (Agofollin Depot, 1 mg s.c. once a week) we determined in the first part of 70 days old female rats the uptake of 85Sr-microspheres and local blood flow in the tibia, in the second part 24 hours' incorporation of 45Ca and 3H-proline and in the third part 2 hours' uptake of 85Sr, bone density and ash weight related to 1 ml of bone volume. We observed the following statistically significant changes: decrease in the uptake of 85Sr-microspheres and local blood flow, decrease in the incorporation of 45Ca, 3H-proline and 85Sr, increase in the density and ash weight of the tibia. The rise of bone mineral content simultaneously with reduced indicators of bone formation and particularly of the mineralization seems to be in the connection with the suppression of bone resorption under the influence of estrogen. Qualitatively identical reactions of circulatory and metabolic indicators to the administration of estradiol may be a reflection of mutual physiological interconnections.

Animals↗

PubMed1993

Interrelations between body weight, cigarette smoking and spine mineral density in osteoporotic Czech women.

This study was designed to assess the influence of body weight and cigarette smoking on vertebral bone mineral density in 241 osteoporotic and age matched 98 normal Czech women. The present study demonstrated that bone density and the frequency of atraumatic vertebral fractures was not related to the body weight. High body weight was not found to show any protective action on bone. However, among a group with vertebral fractures, bone mineral density in cigarette smokers was significantly lower than in nonsmokers, but this effect was not associated with low body weight. The osteoporotic women with and without vertebral fractures had high serum cholesterol concentration which is unequivocally associated with peripheral vascular disease. Thus, our results are suggesting the relationship between atherosclerosis and osteoporosis.

Aged↗

PubMed1992

[Hydrocortisone decreases blood flow in bones in sham-operated and oophorectomized female rats].

In an experiment on 38 75-day-old female rats--sham-operated or oophorectomized (OOX)--the authors assessed the effect of hydrocortisone administration (0.01% in the diet for four weeks) on the blood flow in the tibia and distal end of the femur (uptake of 85Sr microparticles). In the tibia they assessed also the density (according to the Archimed principle) and the weight of ashes per volume unit of bone. OOX increases significantly local circulation in both bones. After hydrocortisone these values are significantly lower in sham-operated and OOX rats as compared with controls and also significantly lower in the group OOX+hydrocortisone, as compared with group OOX. The density and weight of ashes from the tibia are not affected by hydrocortisone; the minute volume of the heart per 100 g body weight of rats is not altered in any group. The mechanism of the described hydrocortisone effects on circulation is not known. In the discussion the authors indicate possible associations of blood flow and the osteoblast and prostaglandin function in bony tissue.

Animals↗

PubMed1992

Further findings on the inhibitory effect of estradiol benzoate on the circulation and on 45Ca and 3H-proline incorporation in rat bones.

Various aspects of the effect of estradiol benzoate (EB, Agofollin Depot, Czechoslovakia, usually in a s.c. dose of 5 mg/kg body weight once a week), on the local circulation (the uptake of 85Sr-microspheres), the incorporation of 45Ca and 3H-proline, bone density and ash weight related to bone volume were studied in six experiments in the tibia and distal femur of 224 rats. 1. The dose-response. In rats treated four weeks with doses of 0.5, 1.0, 1.5 and 2.0 mg EB per rat once a week, a significant correlation with the uptake of 85Sr-microspheres (r = -0.56), the blood flow (r = -0.56), the incorporations of 45Ca (r = -0.89) and 3H-proline (r = -0.35) and body weight (r = -0.71) was demonstrated. 2. The time course of changes after 1, 2, 4 and 8 weeks administration of EB. Circulatory values were not significantly lowered until after four weeks, 45Ca incorporation and body weight were significantly lower after only one week and 3H-proline incorporation did not fall until after eight weeks. The course of the uptake of 85Sr-microspheres and the incorporation of 45Ca were very similar. 3. Comparison of males and females. EB reduced circulatory values and 45Ca and 3H-proline incorporation and increased bone density and bone ash weight in both males and females. Conclusions. The decrease in the local bone blood flow after EB showed a significant dose-effect correlation; the decrease in circulatory values, on using the given administration method, is significant after four weeks. The inhibitory effect of EB on the bone blood flow is not sex-specific.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Different effects of oestradiol benzoate and norethisterone on the blood flow and mineral content in rat bones.

In three experiments (2 on females, 1 on males), we determined the blood flow in the tibia and the distal part of the femur, together with cardiac output (by means of 85Sr-microspheres), tibial bone density and tibial ash weight related to bone volume. We found that 1) the bone blood flow always fell significantly after oestradiol benzoate, 2) no change occurred after norethisterone in doses corresponding to those of oestradiol benzoate, but the blood flow showed a tendency to fall after doses one order higher (it decreased significantly in one case only), 3) the density of the tibia and tibial ash weight related to bone volume rose nonsignificantly after oestradiol benzoate, but fell (mostly statistically significantly) after norethisterone. The lowering of the bone mineral indexes in rat bones after norethisterone is a surprising and potentially significant finding requiring further verification.

Animals↗

PubMed1991

[Relation between levels of atrial natriuretic factor and circulating plasma volume].

The authors investigated in a group of 50 subjects the influence of changes in the volume of circulating plasma on the feedback regulation of plasmatic concentrations of the atrial natriuretic factor (ANF). They proved a fairly close direct correlation between the plasma concentration of ANF and the plasma volume in litres (r = 0.465, p less than 0.01) and when expressed in percent of body weight (r = 0.546, p less than 0.01). The rising concentration of ANF with the patients' age (r = 0.381, p less than 0.01) may be due to actual age conditioned changes or the more frequent incidence of pathological conditions in more advanced age groups, leading to an increase of the ANF plasma level. The results indicate that in addition to pressure changes and distension of the atria in the regulation of the plasma concentration of ANF also changes in the circulating plasma and blood volume participate which thus influence by a feedback mechanism the volume homeostasis.

Adult↗

PubMed1991

[Dual-photon densitometry of the lumbar spine. Further experience and findings].

The authors submit further experience with two-photon absorption measurement of the mineral content of the lumbar spine using a NOVO/Lab BMC 22a (Denmark) apparatus. 1. The authors discuss the problem of evaluation of results in postmenopausal women. For the basic evaluation the authors use the range +/- 2 s of "normal" values classified by decades; another suitable guide to the interpretation could be extrapolation of the lower range of the regression zone in recorded in premenopausal women to higher age groups. 2. The histogram of frequencies of normal values in women in g.cm-2 has two peaks corresponding to the group of premenopausal women and the group of postmenopausal women. 3. Of 573 examined patients with osteoporosis 295, i. e. 51.5%, cannot be reliably evaluated or cannot be evaluated at all (as a rule because of changes of the spine). Of 49 results obtained in men with osteoporosis 34.7% are within the normal range, of 229 results obtained in women with osteoporosis 47.2% are within the normal range. The hitherto assembled experience is consistent with the view that the method is useful and invaluable in particular for the long-term follow up of patients.

Absorptiometry, Photon↗

PubMed1991

[Dangers of postischemic cerebral hyperemia].

The authors draw attention to the danger of the development of hyperaemia because of the possible influence of free oxygen radicals during the hypoxic period on brain cells. Using radioactive microparticles of 85Sr the authors assessed the cardiac minute volume and blood flow through the medulla oblongata, cerebellum, subcortical area and cerebral cortex in adult laboratory rats 20 hours after 2-minute ischaemia induced by positive radial acceleration of 10 G. The results indicate an increase of the local blood supply in the investigated parts of the brain, although lower than after 8-hour exposure to high altitude hypoxia at 7000 m.

Animals↗

PubMed1991

[Increased blood flow and incorporation of 3H-proline and 45Ca into the bones of female rats after oophorectomy].

In the submitted experiment the authors investigated changes of the local circulation (by assessing retention of 85Sr microparticles) and incorporation of 3H-proline and 45Ca in bone of female rats following oophorectomy (OOX). Four weeks after OOX retention of 85Sr microparticles in % from 1 g tissue rises significantly in the tibia, distal epiphysis of the femur and in vertebrae (insignificantly in the metaphysis and calva); the blood flow in (1 min-1).kg-1 is significantly increased in the tibia and diaphysis of the femur (the differences are less significant as the scatter of values is greater). No differentiation was found in the circulatory response with regard to the content of compact and trabecular tissue in the tested bone or part of a bone. In the examined soft tissues after OOX no detectable changes of the local circulation were found. It appears thus that the local circulatory reaction after OOX is specific only for bony tissue. Twenty-four hour incorporation of 3H-proline and 45Ca into the tibia of female rats is significantly raised after OOX - along with a rise of circulatory values these changes are obviously part of the enhanced metabolic activity of bony tissue after OOX. The specific reaction of the local circulation in bones to oestrogen deficiency is a potentially significant aspect of their action.

Animals↗

PubMed1991

[Reduced blood flow in bones in female rats after administration of estrogen].

The authors submit the results of investigations of the action of oestrogens on the blood flow in bones and other tissues of female rats (by means of 85Sr microparticles) on the incorporation of 3H-proline and 45Ca into bone marrow and on bone density and weight of the ashes. Daily s.c. injections of oestradiol dipropionate (Agofollin Spofa, CSFR, 0.1 mg per 100 g) reduce the blood flow in the tibia already on the first days and significantly on the 9th day of administration. After four injections of oestradiol benzoate with protracted action (Agofollin Depot Spofa, 1 mg.s.c. once a week) the retention of 85Sr microparticles is significantly reduced in the distal epiphysis of the femur, in both terminal portions of the tibia and in vertebrae; the blood flow is significantly reduced in the distal epiphysis of the femur and in the proximal end of the tibia. Among various soft tissues where measurements were made only in the kidneys a significant drop of the local circulation was recorded. Twenty-four hour incorporation of 3H-proline and 45Ca into the tibia is significantly reduced after depot oestradiol benzoate. Under the same conditions an inconstant significant rise of bone density or weight of the ash per volume of bone was found. Oestrogen administration to female rats thus causes a drop of the local circulation in bones, in particular in trabecular tissue (among soft parts only in the kidneys) and at the same time a reduced formation of bone matrix and the process of mineralization. So far we are unable to explain the mechanism and impact of the observed reactions.

Animals↗

PubMed1990

Estradiol benzoate decreases the blood flow through the tibia of female rats.

Effect of estradiol benzoate (EB, Agofollin Depot Spofa, CSSR, 1 mg s.c. once a week for 4 weeks) on local blood flow through the tibia of intact and oophorectomized (OOX) female rats was studied using the 85Sr-microsphere method. In experiment A, the 85Sr-microsphere uptake and blood flow was increased 4 weeks after OOX and significantly decreased after EB in both the intact and OOX animals. In experiment B (intact female rats), the decrease after EB was confirmed both in microsphere uptake and tibial blood flow (48.8% and 57.1% respectively). No changes in the cardiac output and the marked fall of the uptake of labelled microspheres suggest a local circulatory reaction.

Animals↗

PubMed1990

[Circulatory changes in the rat tibia in dietary calcium and vitamin D deficiency. Effects of age and sex].

In previous experiments (4) we observed in laboratory rats after a low Ca content diet with no vitamin D a decrease of blood flow through bones. In this study we follow whether the effect of the deficit diet is influenced by age or sex of experimental animals. Tibia blood flow in rats is established by 85Sr-microparticles, bone density is estimated by weighing the bone under water. After 10 days of feeding by the deficit diet 85Sr-microparticles catchment in young males is decreased to 74% of that of controls, in young females to 61%, blood flow is decreased to 46% and 51% respectively. In older males after the diet the microparticles catchment is significantly decreased to 63%, blood flow is non-significantly decreased to 82% (as a result of higher cardiac output). In the category of older females the effect of deficient diet is not demonstrable as regards both microparticles catchment and blood flow. Bone density in preliminary experiment after 40 days of diet is significantly decreased in males of both age categories and in young females, in the main experiment after 10 days of diet it is decreased only in the categories of young males and females. From the results obtained in following the effect of diet deficient in Ca and vitamin D on density and local blood flow in tibia of rats can be concluded 1) that in this respect younger rats are more susceptible, 2) in the category of older males the effect is partly demonstrable in males, but not in females.

Age Factors↗

PubMed1990

[Reactive hyperemia in the brain of rats after high altitude hypoxia].

Using radioactive microparticles of Sr85 the authors assessed the cardiac minute volume and blood flow through the medulla oblongata, cerebellum, subcortical portions and cerebral cortex in adult laboratory rats 20 hours after 8-hour exposure to high altitude hypoxia of 7000 m. The local blood supply is increased in all parts of the brain, in particular in the medulla oblongata and cerebellum.

Altitude↗