Biomedical subjects

J Koska

Publications and source records attributed to J Koska.

At least 19 recordsLinked to original sources

PubMed2004

Hypothalamic-pituitary-adrenal axis function in ankylosing spondylitis.

OBJECTIVE: To assess basal function and responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in patients with ankylosing spondylitis during dynamic testing. METHODS: Insulin induced hypoglycaemia (IIH) (Actrapid HM 0.1 IU/kg, as intravenous bolus) was induced in 17 patients and 11 healthy controls matched for age, sex, and body mass index. Concentrations of glucose, adrenocorticotrophic hormone (ACTH), cortisol, insulin, dehydroepiandrosterone sulphate (DHEAS), 17alpha-hydroxyprogesterone, interleukin 6 (IL-6), and tumour necrosis factor alpha (TNFalpha) were determined in plasma. RESULTS: Comparable basal cortisol levels were found in the two groups, with a trend to be lower in ankylosing spondylitis. In the ankylosing spondylitis group, there were higher concentrations of IL-6 (mean (SEM): 16.6 (2.8) pg/ml v 1.41 (0.66) pg/ml in controls; p<0.001) and TNFalpha (8.5 (1.74) pg/ml v 4.08 (0.42) pg/ml in controls; p<0.01). Glucose, insulin, ACTH, DHEAS, and 17alpha-hydroxyprogesterone did not differ significantly from control. The IIH test was carried out successfully in 11 of the 17 patients with ankylosing spondylitis, and the ACTH and cortisol responses were comparable with control. General linear modelling showed a different course of glycaemia (p = 0.041) in the ankylosing spondylitis patients who met the criteria for a successful IIH test compared with the controls. CONCLUSIONS: The results suggest there is no difference in basal HPA axis activity and completely preserved responsiveness of the HPA axis in patients with ankylosing spondylitis. The interpretation of the different course of glycaemia during IIH in ankylosing spondylitis requires further investigation.

17-alpha-Hydroxyprogesterone↗

PubMed2004

Does orthostatic stress influence the neuroendocrine response to subsequent hypoglycemia in humans?

Neuroendocrine response to stress stimuli is influenced by previous stimuli of different nature. The aim of the study was to test whether antecedent orthostatic stress may affect the neuroendocrine response to subsequent hypoglycemia. A group of 12 (6 men, 6 women) nonobese, healthy volunteers aged 19 to 27 y (mean 24 +/- 0.8) participated in the study in two sessions: controlled insulin-induced hypoglycemia to 2.7 mmol/L for 15 min either with or without antecedent orthostatic stress (30 min of 60 degrees head-up tilt before insulin administration). Orthostatic stress caused a significant decrease in plasma volume (-9.6%; P < 0.001) and a significant increase in plasma renin activity, aldosterone, norepinephrine (P < 0.01), and adrenocorticotropic hormone (ACTH) concentrations (P < 0.05) in all subjects. Growth hormone response to hypoglycemia was diminished in women (P < 0.01). The epinephrine response to hypoglycemia was diminished in women in comparison to men (P < 0.001), but was unaffected by antecedent orthostatic stress. Hypoglycemia failed to induce the ACTH release after its elevation during orthostatic stress. ACTH response to moderate hypoglycemia without previous orthostatic stress was evident only in men in comparison to women (P < 0.05). We conclude that the epinephrine, growth hormone, and ACTH responses to hypoglycemia were diminished in women. Except ACTH, the neuroendocrine response to mild hypoglycemia was not affected by previous orthostatic stress in healthy subjects. In the case of ACTH, the first stress stimulus is consequential for the subsequent response of this hormone, probably due to short-loop negative feedback effects.

Adult↗

PubMed2003

The response of endocrine system to stress loads during space flight in human subject.

The responses of endocrine system to the exposure to stress-work load and hormonal changes during oral glucose tolerance tests were studied in the Slovak astronaut before (three weeks before flight), during (on the 4th and the 6th days of space flight), and after space flight (1-3 days and 15-17 days after space flight) on board of space station MIR. Blood samples during the tests were collected via cannula inserted into cubital vein, centrifuged in the special appliance Plasma-03, frozen in Kryogem-03, and at the end of the 8-day space flight transferred to Earth in special container for hormonal analysis. Preflight workload produced an increase of plasma norepinephrine and a moderate elevation of epinephrine levels. Plasma levels of insulin, growth hormone, prolactin and cortisol were not markedly changed immediately or 10 min after the end of work load. The higher increases of plasma growth hormone, prolactin and catecholamine levels were noted after workload during space flight as compared to preflight response. The higher plasma glucose and insulin levels were noted during the oral glucose tolerance test in space flight and also in the post flight period. Plasma epinephrine levels were slightly decreasing during glucose tolerance test; however, plasma norepinephrine levels were not changed. The similar patterns of catecholamine levels during glucose tolerance test were found when compared the preflight, in-flight and post flight values. These data demonstrate the changes of the dynamic responses of endocrine system to stress-work and metabolic loads during space flight in human subject.

Adaptation, Physiological↗

PubMed2003

Growth hormone and prolactin responses during partial and whole body warm-water immersions.

AIM: To elucidate the role of core and skin thermoreceptors in the release of growth hormone (GH) and prolactin (PRL), a sequence of two experiments using whole-body (head-out) and partial (one forearm) hot water immersions was performed. METHODS: Experiment 1: Nine healthy men were exposed to head-out and partial water immersions (25 min, 38-39 degrees C). RESULTS: Head-out immersion increased the core temperature (38.0 +/- 0.1 vs. 36.7 +/- 0.1 degrees C, P < 0.001) and plasma concentration of the hormones (GH, 16.1 +/- 4.5 vs. 1.2 +/- 0.4 ng mL(-1), P < 0.01; PRL, 9.1 +/- 1.0 vs. 6.4 +/- 0.4 ng mL(-1), P < 0.05). During the partial immersion the core temperature was slightly elevated (36.8 +/- 0.1 vs. 36.6 +/- 0.1, P < 0.001), the concentration of GH increased (4.8 +/- 1.7 vs. 0.6 +/- 0.3, P < 0.05), while plasma PRL decreased (7.6 +/- 0.8, 6.0 +/- 0.6, 5.2 +/- 0.6, P < 0.01). Experiment 2: Seven volunteers immersed one forearm once in 39 degrees C and once in 38 degrees C water. The measurements were performed in 5-min intervals. The GH concentration increased gradually from the beginning of the immersions (min 10; 39 degrees C: 1.9 +/- 1.0 vs. 0.6 +/- 0.3 ng mL(-1), P < 0.01; 38 degrees C: 0.19 +/- 0.03 vs. 0.14 +/- 0.03, P < 0.05) and peaked after their completion (39 degrees C: +10 min, 3.7 +/- 2.0, P < 0.001; 38 degrees C: +15 min, 0.86 +/- 0.61, P < 0.01). The core temperature was unchanged until min 15 of the 39 degrees C bath. Thereafter, it increased about 0.15 degrees C above the baseline (P < 0.01). Immersion in 38 degrees C water did not induce core temperature changes. CONCLUSIONS: Peripheral thermoreceptors are involved in GH release when the body is exposed to elevated environmental temperature while a substantial elevation of core temperature is a precondition of PRL release.

Adult↗

PubMed2003

Cortisol elimination from plasma in premenopausal women with rheumatoid arthritis.

OBJECTIVE: To test the hypothesis that cortisol elimination from plasma can contribute to relatively low cortisol in premenopausal women with rheumatoid arthritis (RA). METHODS: Twelve premenopausal female patients with RA (39.8 (1.8) years) and nine healthy control women matched for age and body mass index (42 (3.3) years) were enrolled in the study. None of the patients had previously been receiving treatment with glucocorticoids. After dexamethasone suppression (2 mg by mouth) the evening before the study, 20 mg of hydrocortisone was given. Blood and saliva samples were drawn six hours after injection of hydrocortisone. Plasma and salivary cortisol were measured. RESULTS: Dexamethasone administration suppressed plasma cortisol concentrations to an almost undetectable level in all subjects, except one with RA. In this subject, a raised concentration of plasma cortisol was verified by repeated analysis despite the fact that cortisol concentration in the saliva sample measured simultaneously was not raised. No significant difference in the disappearance curve of cortisol in plasma or in salivary cortisol levels was found between the patients with RA and the healthy controls. CONCLUSIONS: The profile of disappearance of total cortisol from plasma, and salivary cortisol levels during the elimination phase after its intravenous administration, are unchanged in premenopausal women with RA. Alterations in cortisol clearance are not likely to have a role in cortisol availability in patients with RA.

Adult↗

PubMed2003

Effect of head-down bed rest on the neuroendocrine response to orthostatic stress in physically fit men.

The role of neuroendocrine responsiveness in the development of orthostatic intolerance after bed rest was studied in physically fit subjects. Head-down bed-rest (HDBR, -6 degrees, 4 days) was performed in 15 men after 6 weeks of aerobic training. The standing test was performed before, after training and on day 4 of the HDBR. Orthostatic intolerance was observed in one subject before and after training. The blood pressure response after training was enhanced (mean BP increments 18+/-2 vs. 13+/- 2 mm Hg, p<0.05, means +/- S.E.M.), although noradrenaline response was diminished (1.38+/-0.18 vs. 2.76+/-0.25 mol.l(-1), p<0.01). Orthostatic intolerance after HDBR was observed in 10 subjects, the BP response was blunted, and noradrenaline as well as plasma renin activity (PRA) responses were augmented (NA 3.10+/-0.33 mol.l(-1), p<0.001; PRA 2.98+/-1.12 vs. 0.85+/-0.15 ng.ml(-1), p<0.05). Plasma noradrenaline, adrenaline and aldosterone responses in orthostatic intolerant subjects were similar to the tolerant group. We conclude that six weeks of training attenuated the sympathetic response to standing and had no effect on the orthostatic tolerance. In orthostatic intolerance the BP response induced by subsequent HDBR was absent despite an enhanced sympathetic response.

Adult↗

PubMed2003

[Use of the in vivo microdialysis technique in basic and clinical research].

Microdialysis is in vivo technique that permits monitoring of local concentrations of metabolites and drugs at specific sites in the body that makes it an attractive tool for the basic and clinical research. Microdialysis entered the experimental studies of the brain, and later also of the peripheral tissues such as adipose and muscle tissues, kidney, lung, eye, skin, and blood. There are several critical factors in the experimental implementations of microdialysis: the probe, the perfusion solution, tissue integrity, and the sensitivity of microdialysate analysis method. When the experimental conditions are optimised to give valid results, microdialysis can provide numerous data from the relatively small number of individual subjects. It can bring about detailed clinical information reflecting free metabolite and drug concentrations in studied tissues and/or in plasma. With the progress of analytical methods, applications and importance of the microdialysis technique in clinical and pharmacokinetic research and diagnostics will increase.

Humans↗

PubMed2003

Thyroid function and cholesterol level: paradoxical findings in large groups of population with high cholesterol food intake.

OBJECTIVE: To compare the levels of serum cholesterol with thyroid function as estimated by the level of thyrotropin and free thyroxine with possible participation of thyroperoxidase antibodies in large number of adults examined within large field surveys focused on the evaluation of thyroid status of Slovak rural population. SUBJECTS AND METHODS: Serum level of cholesterol and thyrotropin (TSH) was estimated in a total of 2786 adults. In addition, in 2038 of them also the level of free thyroxine (FT4), total triiodothyronine (TT3), cholesterol, triglycerides and phospholipids was measured. The levels of TSH, anti-TPO and FT4 were estimated by supersensitive electrochemiluminiscent immunoassay using the automatic system Elecsys (Roche, Switzerland). RESULTS: A total of 2786 adults was stratified into 7 groups according to the range of TSH level as related to generally recognized level of thyroid function, e.g. 1. TSH <0.10 mU/L (overt hyperthyroidism, N=41), 2. TSH 0.11-0.30 mU/L (overt or subclinical hyperthyroidism, N=149), 3. TSH 0.31-2.50 mU/L (normal level, N=1750), 4. TSH 2.51-4.50 ("high normal" level, N=607), 5 TSH 4.51-6.50 (mild or incipient subclinical hypothyroidism, N=137), 6. TSH 6.51-10.00 mU/L (mild hypothyroidism, N=50), 7. TSH 10.01-99.00 mU/L (severe hypothyroidism, N=53). The average levels of cholesterol in all groups were very similar ranging from 5.53 to 6.17 mmol/L and no interrelations with TSH level were found. In addition, no considerable differences between these groups were found when considering the levels of medians, upper quartiles and 90th percentiles of individual groups. When male and female subjects were divided into age groups according to the decades, an age dependent increase of cholesterol level was found in both sexes. The fraction of 2038 subjects was divided into the same TSH related groups as defined above. Similarly as above, no considerable differences in cholesterol, triglycerides and phospholipids level were observed. However, the levels of FT4 and TT3 were significantly decreasing with the increase of TSH level which confirmed the continuing decrease of thyroid function. The frequency of positive anti-TPO in subjects with TSH >6.5 mU/l (71/86 = 82.5%) was significantly higher than that in subjects with TSH <6.5 mU/l (468/1952 = 23.9%). CONCLUSIONS: No difference in the level of cholesterol and triglycerides was found in large groups of rural adults from Slovakia with various thyroid function as estimated by the level of TSH, FT4, TT3 and anti-TPO. It is assumed that this interrelation resulted from very high cholesterol intake due to inappropriate general nutritional status of rural population resulting from the consumption of unhealthy foods.

Adult↗

PubMed2002

Effect of simulated microgravity on endocrine response to insulin-induced hypoglycemia in physically fit men.

Adaptation to microgravity is associated with alteration in some endocrine functions. In the present longitudinal study, the counterregulatory hormonal response to insulin-induced hypoglycemia (ITT, 0.1 IU/kg short acting insulin i. v.) was evaluated under simulated microgravity conditions in 15 physically fit subjects. ITT was performed at the beginning of the investigation, and again after completion of 6 weeks of endurance training and after a subsequent period of 4 days of head-down bed rest at a backward tilt of 6 degrees from the horizontal. Endurance training showed a significant increase in maximal aerobic capacity in previously well-trained subjects (increase by 12 %), as well as on attenuation of counterregulatory response of epinephrine to hypoglycemia. After 4 days of bed rest, basal concentrations of plasma norepinephrine was diminished (p < 0.002) and plasma renin activity was enhanced (p < 0.02). After bed rest, decreased responses of the two catecholamines (norepinephrine, p < 0.001; epinephrine, p < 0.001), growth hormone (p < 0.001), and cortisol (p < 0.05) were observed. Response of plasma renin activity after bed rest was increased (p < 0.01). This longitudinal study indicated that 4 days of bed rest in endurance-trained subjects induced increased response of PRA to hypoglycemia and attenuation of other counterregulatory neuroendocrine responses.

Adult↗

PubMed2002

Hyperprolactinemia does not influence hypothalamic-pituitary-adrenocortical function during hypoglycemia in women.

Elevated plasma prolactin and mild hypocortisolemia have been observed in patients with rheumatic disorders. This study was designed to assess the potential inhibitory effect of hyperprolactinemia on hypothalamic-pituitary-adrenocortical function. Hypoglycemia was induced by intravenous insulin injection (0.1 IU/kg) in 10 female volunteers of fertile age during their follicular phase twice: 60 min after either domperidone (10 mg orally) or placebo administration. Blood samples were collected from an indwelling catheter inserted into the cubital vein at -60, 0, 30, 45, 60 and 90 min. The concentrations of prolactin, adrenocorticotropic hormone (ACTH), cortisol, epinephrine, norepinephrine and glucose were measured in plasma. Domperidone administration significantly increased plasma prolactin concentrations (71 +/- 11 ng/ml vs. 14 +/- 6 ng/ml; p <0.001), while basal plasma concentrations of ACTH, cortisol, norepinephrine and epinephrine were unaffected. Insulin-induced hypoglycemia resulted in a significant rise in the mean plasma ACTH levels from 10 +/- 1 pg/ml (domperidone) and 11 +/- 1 pg/ml (controls) to 148 +/- 19 pg/ml (domperidone) and 139 +/- 12 pg/ml (controls) at 45 min (p < 0.001), in plasma cortisol from 407 +/- 62 nmol/l (domperidone) and 391 +/- 42 nmol/l (controls) to 925 +/- 60 nmol/l (domperidone) and 810 +/- 52 nmol/l (controls) at 60 min (p < 0.001), and in plasma epinephrine from 40 +/- 26 pg/ml (domperidone) and 16 +/- 3 pg/ml (controls) to 274 +/- 55 pg/ml (domperidone) and 352 +/- 61 pg/ml (controls) at 30 min; (p < 0.001). The significant increase in ACTH, cortisol and epinephrine responses to hypoglycemia was similar in both groups. We observed mild norepinephrine response to hypoglycemia but this was irrespective of the medication. In conclusion, pharmacologically-induced hyperprolactinemia did not induce significant changes of hypothalamic-pituitary-adrenocortical function and did not influence sympathoadrenal activity in healthy young women.

Adrenal Cortex↗

PubMed2002

Responses of sympathoadrenal and renin angiotensin systems to stress stimuli in humans during real and simulated microgravity.

Changes of plasma hormone levels were investigated in human subjects after exposure to physical exercise (WL) and insulin induced hypoglycemia (ITT) during space flight or after head down bed rest (HDBR). Exaggerated responses of plasma epinephrine (EPI), norepinephrine (NE) and aldosterone (ALD) were observed after WL during space flight as compared to preflight response. Hypoglycemia during space flight induced attenuated responses of EPI, NE and augmented response of ALD. Exposure to WL during HDBR was followed by significantly exaggerated responses of plasma EPI, NE, ALD, PRA and cortisol. In HDBR the responses of plasma EPI, NE and cortisol were reduced and PRA response was exaggerated during ITT. These data indicate that hormonal responses to ITT and WL are similar at real and simulated microgravity.

Comparative Study↗

PubMed2001

Effect of microgravity on plasma catecholamine responses to stressors during space flight.

The effect of microgravity on the sympathicoadrenal system (SAS) activity in humans and animals has not yet been clarified. Our previous studies suggested that the SAS activity, evaluated by circulating and/or urinary catecholamine (CA) levels in astronauts during space flights, was found to be rather unchanged. However, CA levels were measured in astronauts only at rest conditions. The aim of the present study was to investigate effect of microgravity during space flight and post-flight readaptation on responsiveness of the SAS to somatic and psychic stressors evaluated by levels of catecholamines and their metabolite in the blood of the Slovak cosmonaut during his stay on board the space station Mir.

Adaptation, Physiological↗

PubMed2001

Plasma hormone levels in human subject during stress loads in microgravity and at readaptation to Earth's gravity.

In great part of the investigations of endocrine system functions in astronauts during space flights the plasma levels of hormones and metabolites were determined only in resting conditions, usually from one blood sample collection. Such levels reflected the psychical and physical state and new hormonal homeostasis of organism at the time of blood collection, however, the functional capacity of neuroendocrine system to respond to various stress stimuli during space flight remained unknown. The aim of present investigations was to study dynamic changes of hormone levels during the stress and metabolic loads (insulin induced hypoglycemia, physical exercise and oral glucose tolerance test) at the exposure of human subject to microgravity on the space station MIR. The responses of sympatico-adrenomedullary system to these stress and workloads were presented by Kvetnansky et al.

Adaptation, Physiological↗

PubMed2000

Analysis of brush-particle interactions using self-consistent-field theory.

Non-specific protein adsorption can be reduced by attaching polymer chains by one end to a sorbent surface. End-grafted polymer modified surfaces have also found application in size-based chromatographic bioseparations. To better understand how to tailor surfaces for these applications, a numerical SCF model has been used to calculate theoretical results for the polymer density distribution of interacting polymer chains around a solute particle positioned at a fixed distance from a surface. In addition, the excess energy required to move the particle into the polymer chains (interaction energy) is calculated using a statistical mechanical treatment of the lattice model. The effect of system variables such as particle size, chain length, surface density and Flory interaction parameters on density distributions and interaction energies is also studied. Calculations for the interaction of a solute particle with a surface covered by many polymer chains (a brush) show that the polymer segments will fill in behind the particle quite rapidly as it moves toward the surface. When there is no strong energetic attraction between the polymer and solute we predict that the interaction energy will be purely repulsive upon compression due to losses in conformational entropy of the polymer chains. Above a critical chain length, which depends upon particle size, a maximum in the force required to move the particle toward the surface is observed due to an engulfment of the particle as chains attempt to access the free volume behind the particle. If an attraction exists between the polymer and solute, such that a minimum in the interaction energy is seen, the optimum conditions for solute repulsion occur at the highest surface density attainable. Long chain length can lead to increased solute concentration within the polymer layer due to the fact that an increased number of favourable polymer-solute contacts are able to occur than with short chains at a similar entropic penalty.

Entropy↗

PubMed2000

Insulin, catecholamines, glucose and antioxidant enzymes in oxidative damage during different loads in healthy humans.

Exercise, insulin-induced hypoglycemia and oral glucose loads (50 g and 100 g) were used to compare the production of malondialdehyde and the activity of antioxidant enzymes in healthy subjects. Twenty male volunteers participated in the study. Exercise consisted of three consecutive work loads on a bicycle ergometer of graded intensity (1.5, 2.0, and 2.5 W/kg, 6 min each). Hypoglycemia was induced by insulin (Actrapid MC Novo, 0.1 IU/kg, i.v.). Oral administration of 50 g and 100 g of glucose was given to elevate plasma glucose. The activity of superoxide dismutase (SOD) was determined in red blood cells, whereas glutathione peroxidase (GSH-Px) activity was measured in whole blood. The concentration of malondialdehyde (MDA) was determined by HPLC, catecholamines were assessed radioenzymatically and glucose was measured by the glucose-oxidase method. Exercise increased MDA concentrations, GSH-Px and SOD activities as well as plasma noradrenaline and adrenaline levels. Insulin hypoglycemia increased plasma adrenaline levels, but the concentrations of MDA and the activities of GSH-Px and SOD were decreased. Hyperglycemia increased plasma MDA concentrations, but the activities of GSH-Px and SOD were significantly higher after a larger dose of glucose only. Plasma catecholamines were unchanged. These results indicate that the transient increase of plasma catecholamine and insulin concentrations did not induce oxidative damage, while glucose already in the low dose was an important triggering factor for oxidative stress.

Adult↗

PubMed2000

Role of body temperature in exercise-induced growth hormone and prolactin release in non-trained and physically fit subjects.

OBJECTIVE: To study the role of physical fitness and hyperthermia in inducing growth hormone (GH) and prolactin (PRL) responses to exercise in physically fit and in non-trained healthy subjects. METHODS: Ten wrestlers preparing for international competition (mean age 19), and nine untrained healthy males (mean age 21), volunteered in the study. They were exposed twice to the exercise consisting of 27 min swimming, freestyle, in water of 29 or 36 degrees C, with last 3 min increased to maximal effort. Measurement of blood pressure, heart rate, sublingual temperature and sampling of blood was performed before exercise, immediately after and after a 30-min period of rest. RESULTS: Body temperature, heart rate, systolic blood pressure and plasma growth hormone (GH) were significantly elevated in both groups after swimming in water of either temperature (P < 0.01). The difference between GH responses to swimming in water of 29 degrees C vs 36 degrees C was significant only in non-trained subjects and was associated with the changes of body temperature. A rise in PRL concentration was found only in exercise in warmer water (P < 0.01). There were no statistical differences between athletes and controls in any response to swimming in water of the same temperature. CONCLUSIONS: The augmented release of GH and PRL was the result of direct stimulation by increased body temperature.

Adult↗

PubMed2000

Effect of hyperthermic water bath on parameters of cellular immunity.

Effects of hyperthermic water bath on selected immune parameters (lymphocyte subpopulations, natural killer (NK) cell counts and their activity) were studied in a group of 10 volunteers. Application of hyperthermic water bath (both topical and whole-body) was followed by a significant reduction of relative B lymphocyte counts. Whole-body hyperthermic water bath reduced relative total T lymphocyte counts, increased relative CD8+ T lymphocyte and NK cell counts and increased NK activity. Whole-body hyperthermic bath increased somatotropic hormone (STH) activity in eight out of 10 volunteers; higher relative counts of CD8+ lymphocytes and NK cells were observed compared with the group of volunteers not responding to hyperthermic water bath by STH secretion. In five volunteers STH was released in response to local hyperthermic water bath and the NK activity of lymphocytes also increased but their relative counts did not. The results suggest that these increases in CD8+ lymphocyte and NK cell counts are probably dependent on increased STH production.

Adult↗

PubMed1999

Malondialdehyde, lipofuscin and activity of antioxidant enzymes during physical exercise in patients with essential hypertension.

DESIGN: To clarify the role of oxidative damage in essential hypertension, levels of lipid peroxidation products (malondialdehyde and lipofuscin) and activity of antioxidant enzymes (superoxide dismutase and glutathione peroxidase) were examined during a short period of physical exercise. PATIENTS AND METHODS: We studied 11 male patients with mild to moderate essential hypertension in World Health Organization classes I or II and 10 healthy male controls. Physical exercise was performed on a bicycle ergometer at graded intensities of 1.0, 1.5 and 2.0 W/kg body weight Plasma concentrations of lipofuscin, malondialdehyde, epinephrine, norepinephrine, insulin, free fatty acids and glucose were determined. Superoxide dismutase activity was analysed in erythrocytes and glutathione peroxidase activity in whole blood. RESULTS: Concentrations of lipofuscin and malondialdehyde were significantly elevated in hypertensive patients. Superoxide dismutase activity was not different between groups, while glutathione peroxidase activity was significantly decreased in hypertensive subjects. During exercise, the concentration of malondialdehyde and antioxidant enzyme activities increased significantly in both groups. No differences were found in absolute increases between the normotensive and hypertensive subjects. The levels of glucose, insulin and free fatty acids were similar in both groups. Basal concentrations of catecholamines and also the exercise-induced increases were lower in hypertensive patients. CONCLUSIONS: Our results indicate increased oxidative damage in patients with essential hypertension, which might be caused by a decrease in the activity of glutathione peroxidase. The ability of superoxide dismutase and glutathione peroxidase to respond to increased production of reactive oxygen species during a short period of physical exercise was not impaired in hypertensive subjects.

Adult↗