[Response to a series of carbon dioxide baths]. / Reakcia organizmu na sériu uhlicitých kúpel'ov.

The authors investigated 28 patients, mean age 43.6 years, during their stay in spa Dudince. The patients had a daily carbon dioxide bath, thermally indifferent, for a period of 20 minutes. During the first, tenth and twentieth bath the humoral circulatory and renal response was assessed. During every bath a standard reaction developed (decline of plasma renin activity and of the aldosterone level, increased excretion of water and minerals, changes of the blood pressure and heart rate). The influence of the series of baths was manifested by a gradual increase of the diuresis, natriuresis, a more permanent drop of the blood pressure and at the end of the series also of the heart rate. The other investigated parameters did not change significantly during the series of baths, as compared with the reaction to a single bath. The attained results justify the conclusion that a series of carbon dioxide baths had a gradually improving effect which is favourable, in particular in the treatment of cardiovascular diseases.

[Combination of a carbon dioxide bath and a diuretic--follow-up study of several days]. / Kombinácia uhlicitého kúpel'a s diuretikom--viacdnové sledovanie.

A series of 22 men underwent a 30 minute carbon dioxide bath and was simultaneously administered Hydrochlorothiazide SPOFA. Their renal response was studied, and that both separately to the bath or the diuretic and to their combination. Diuresis was increased by 200 l x 10(-3) after the carbon dioxide bath and by 500 l x 10(-3) after hydrochlorothiazide. This increase was even further enhanced after the combination of the two treatments. Sodium excretion showed a similar increase, whereas kaliuresis did not exhibit such a marked rise and the differences between the response to the bath and to the diuretic were small. Repeated combination of the carbon dioxide bath and the diuretic resulted in a slightly increasing diuresis over the days studied. The authors emphasize the necessity to understand the bath--drug interactions particularly in balneological practice and substantiate the advantage and usefulness of the combination studied in indicated cases.

Protective effect of oestradiol on the heart of rats exposed to acute ischaemia.

Sex-related differences in mortality from ischaemic heart disease are attributed chiefly to difference in the incidence of atherosclerosis. Little attention has been paid to the influence of sex hormones on resistance of the myocardium itself to acute ischaemia. Experiments on rats showed that isolated female hearts were more resistant than male hearts. A period of eight weeks spent at an altitude of 1,350 m raised heart resistance only in males. Conversely, gonadectomy abruptly reduced the resistance of the male heart to ischaemia, especially under conditions of mild altitude hypoxia. The administration of oestradiol to gonadectomized male rats largely abolished the disturbance caused by isolated gonadectomy. Since coronary vasoconstriction and vasospasm lead to temporary ischaemia and even to infarction, the above effect of the sex hormones may play a role in the increased incidence of heart attacks after the gonads have ceased to function.

Age-dependent influence of a moderate altitude (1,350 m) on the rat cardiopulmonary system.

The aim of the study was to determine whether a moderate altitude (1,350 m, Strbské Pleso, High Tatras) would act as a hypoxic stimulus on the cardiopulmonary system of young and adult rats. We used three experimental groups of animals differing in the duration of time for which they were kept at the given altitude (60 and 120 days) and the age at which they were acclimatized (from the 5th and the 60th day of life). The controls were kept at an altitude of 200 m (Prague). We found that an altitude of 1,350 m produced a significant increase in blood pressure in the lesser circulation; this response did not depend on the animals' age. Right ventricular enlargement occurred at the same time and was more pronounced in rats which had been acclimatized from infancy. The systemic blood pressure fell mildly, but significantly, only in animals exposed to altitude from adulthood; elevation of the haematocrit was likewise recorded only in this group. The results show that even a moderate altitude influences the cardiopulmonary system of the rat in a manner characteristic of the effect of chronic hypoxic hypoxia.

Effects of sauna and glucose intake on TSH and thyroid hormone levels in plasma of euthyroid subjects.

The effect of sauna on thyroid function parameters and its modification by glucose was studied in young euthyroid male volunteers. A 30-minute stay in sauna resulted in an increase in plasma TSH; the response was exaggerated if glycemia had been increased by oral glucose intake at the beginning of the experiment. Plasma rT3 also increased in sauna, this response was, however, blunted by the higher glycemia. TSH response to sauna was definitely present in young men (aged 20 to 25) and absent in middle-aged ones (50 to 55). To explore the mechanism of the effect of increased glycemia, TRH tests were performed and dopamine infusions were administered with and without glucose pretreatment. Increased glycemia did not affect TSH and T3 response to TRH in young volunteers; however, 90 minutes after the administration, plasma rT3 levels were significantly lower in glucose pretreated subjects than in those receiving TRH injections after water pretreatment. Simultaneous infusion of glucose prevented the inhibitory effect of dopamine infusion on plasma TSH. It was concluded that glucose directly modulates the effect of sauna on plasma TSH at a suprapituitary level, while the inhibiting effect of glucose on plasma rT3 response to sauna and TRH is probably mediated by the insulin effect on thyroid hormone metabolism.

Venous plasma adrenaline response to orthostatic syncope during tilting in healthy men.

The effect of transient cerebral ischaemia connected with acute orthostatic hypotension on plasma adrenaline and noradrenaline levels was studied in seven healthy male volunteers during tilt. Sublingual administration of 1 mg nitroglycerin was used to block peripheral vascular reflexes and thus to provoke orthostatic intolerance. A consistent increase in plasma adrenaline concentrations (from 19.2 to 104.3 pg/ml on average, P less than 0.01) was found in six subjects who developed clinical signs of collapse after tilting. Plasma adrenaline never changed after tilting without collapse. Posturally stimulated plasma noradrenaline increases were similar yet irrespective of the presence of collapse.

Increased glucagon secretion during hyperthermia in a sauna.

Plasma glucagon, adrenaline, noradrenaline, insulin and glucose concentrations were measured in 7 healthy young males during hyperthermia in a sauna bath: plasma glucagon levels increased from baseline values of 127.0 +/- 12.9 (SEM) pg X ml-1 to a maximum of 173.6 +/- 16.1 (SEM) pg X ml-1 at the 20th min of exposure. No change in plasma insulin and a slight increase in plasma glucose concentration were seen. Since a concomitant moderate increase in plasma catecholamine levels was also present, the adrenergic stimulus is believed to trigger glucagon release during hyperthermia. Diminished visceral blood flow, known to occur in sauna baths, may cause a decrease in the degradation of plasma glucagon and thus contribute to the elevated plasma glucagon levels.

Impaired glucose utilization in man during acute exposure to environmental heat.

In 6 healthy males the oral glucose tolerance test (OGTT) was performed after the administration of 100 g glucose during the hyperthermic Finnish sauna bath (85 degrees C) of 30 min duration. The lowered insulin response (P less than 0.001) to glucose challenge during heating and the subsequent prolonged hyperglycemia (P less than 0.001) after heating were observed, when compared to OGTT under thermoneutral conditions (23 degrees C). It is suggested that the heat-induced decrease in visceral blood flow and stimulation of sympathoadrenomedullary and pituitary activity may be responsible for this effect.

Response of the rat cardiovascular system to a moderate altitude in connection with endurance training.

The authors investigated whether an altitude of 1,350 m would affect the rat cardiovascular system in the same way as genuine altitude hypoxia and the way it would take effect when combined with endurance training in the form of swimming It was found that 8 weeks spent at this altitude led to an increase in absolute and relative heart weight, to right ventricular hypertrophy, and to increased resistance of the myocardium to acute anoxia. Physical training at a moderate altitude resulted in an increase in the relative weight of the musculature of both the right and the left ventricle and of the septum. Unlike low altitude training, however, growth of the two compartments of the heart was proportional. The resistance of the myocardium of trained animals against anoxia was the same, irrespective of whether they trained at a low or a high altitude. The results show that even a moderate altitude is not a matter of indifference for the rat organism, but that it leads to characteristic manifestations of altitude hypoxia in the cardiovascular system.

TSH response to 30 min stay in sauna in the morning and during evening hours.

The response of plasma TSH to 30 min stay in sauna was compared in the morning and in the evening. Both in the morning and in the evening plasma TSH was significantly elevated after sauna, with more prolonged response in the evening. This difference resembles the different reactivity of TSH to exogenous TRH administration in various times of day.