The relation between antioxidative ability and the diet of young swimmers.

PURPOSE: The comparison of nutrition of children with high level of physical activity in dependence on antioxidative efficiency expressed in Ferric Reducing Ability of Plasma--FRAP adapted for saliva. MATERIAL AND METHODS: The group consisted of 74 pupils (43 boys and 31 girls) from swimming classes of Sport Championship School in Kraków. FRAP was measured in saliva with the use of colorimetric method and was presented in calculation per 1 gram of proteins. Three groups were separated on the basis of FRAP/ protein (g) values distribution of 15 and 85 percentile. In each group the comparison of particular nutritional components was done with taking into consideration the 24 hour nutritional recall. RESULTS: The statistically significant differences in nutrition were observed only in girls group in dependence on the FRAP values. These differences concerned energy and carbohydrates intake. Fats always provided more then 30% of energy, especially among children with high FRAP/ protein (g) value--34.3%. The shortage of proteins was not observed. The mean intake of calcium, and zinc was below and phosphorus, vitamin A and C intake was above the recommended level. CONCLUSIONS: Non-enzymatic mechanisms of antioxidative efficiency (FRAP) are partially being modified by nutritional factors.

The highest ambient temperature tolerated by normocapnic and hypercapnic rabbits.

The highest ambient temperature tolerated by rabbits was 30 degrees C at the relative humidity of air 80-95%. During the exposure to these environmental conditions the vasomotor thermoregulatory response developed fully, while the respiratory frequency did not attain the maximum level, i.e. the rabbit's potential ability for thermal panting. Prolonged heat exposure (approx. 4 hours) had a depressive effect on the respiratory frequency. Increased concentration of carbon dioxide (3, 6 and 9%) in the inspired gas mixture did not disturb the thermoregulatory mechanisms at 30 degrees C in the rabbits.

Reduced hypothalamic thermosensitivity following intraventricular injection of pyrogen in conscious rabbits.

Hypothalamic temperature thresholds for vasodilatory and respiratory reactions were determined before and after i.c.v. injection of pyrogen in rabbits. During the rising phase of fever the increases in the hypothalamic thresholds for vasodilatory and respiratory reactions differed from those found in the pre-pyrogen preoptic anterior hypothalamic area (POAH) heating by 2.1 +/- 0.2 degrees C and 1.89 +/- 0.31 degrees C, respectively. During the plateau phase of fever the threshold for vasodilatory reaction was further increased (by 0.7 +/- 0.23 degrees C), whereas that for panting remained at the same level. It is concluded that pyrogen exerts a depressive action on POAH thermosensitivity.

Dehydration attenuates panting response to intraventricular 5-hydroxytryptamine in the rabbit.

Panting response and a fall in rectal temperature following intraventricular injection of 5-hydroxytryptamine (5-HT) were significantly reduced in dehydrated rabbits as compared with normally hydrated animals. The vasomotor heat loss response to 5-HT was essentially similar in both groups. These as well as earlier findings suggest that dehydration may modify signals generated in brain thermoregulatory centers controlling evaporative but not the vasomotor heat loss.

Effect of nembutal anaesthesia on the tolerance of high ambient temperature in guinea pigs.

A significantly lower rise of rectal temperature was observed in guinea pigs under nembutal general anaesthesia (2 degrees C) in comparison to the rise in this temperature in non-anaesthetised animals (2.6 degrees C) kept for 2.5 hours at an ambient temperature of 36 degrees C. Better tolerance of heat in the animals under general anaesthesia was due to reduced heat production and it was independent of a modification by nembutal of the thermoinsulating properties of the skin and coat, as it is a case at low and neutral ambient temperatures.

Stroke volume and cardiac output hypoxemic hypoxia produced by intravenous infusion of carbon dioxide.

Hypoxia produced by intravenous infusion of gaseous carbon dioxide was associated in conscious rabbits with decreases in cardiac output and stroke volume. At the same time the arterial blood pressure, oxygen uptake and blood pH decreased, whereas carbon dioxide pressure and lactate level in the arterial blood increased. Pulmonary ventilation increased too, due to the rise in the respiratory frequency and tidal volume. The fall in cardiac output and stroke volume explains a great fall of oxygen uptake in response to decrease of oxygen pressure in the blood.

Hypercapnia-induced thermoregulatory disturbances in rabbits at low ambient temperature.

The effect of 30 minute inhalation of a gaseous mixture containing 6% CO2, 21% O2 and 73 N2 on the thermoregulatory reactions was studied in rabbits at ambient temperatures (Ta) of 6 and 18 degrees C. At Ta 6 degrees C the CO2 inhalation caused a greater fall of the rectal temperature (Tre) as well as the subcutaneous and skin temperatures (TS1 and TS2) than at Ta 18 degrees C. At the same time, the gradients Tre-TS1 and TS1-TS2 decreased, the respiratory rate increased and the electrical activity of skeletal muscles was depressed in both thermal conditions. A considerable fall in heat production occurred only at Ta 6 degrees C, at which the initial electric activity of the skeletal muscles was also greater. These results suggest that Tre fall associated with CO2 inhalation at low temperatures was caused mainly by inhibition of shivering-thermogenesis, however, the changes in skin temperatures were without any greater importance for the body temperature at Ta 6 degrees C as well as at 18 degrees C.

Influence of hypercapnia on certain aspects of heat exchanges at room temperature in the rabbit.

Heat production as well as heat loss from the surface of the ear and airways during and after hypercapnia induced by one hour inhalation of 10% mixture was studied in conscious rabbits. The arterial CO2 tension increased by about 45 mm Hg and pH fell by about 0.3. These changes were associated with decreasing of heat production while heat loss from the ears and airways increased significantly. Consequently the rectal temperature fell meanly by about 0.9 degrees C. The data show that fall of body temperature in the rabbits exposed on 10% CO2 at room temperature is due both to heat production changes and heat loss changes.

The effect of environmental temperature on thermoregulatory disturbances caused by hypoxaemic hypoxia in the guinea pig.

Unanaesthetized guinea-pigs, unadapted to cold, were used to study the effect of 20--30 min hypoxaemic hypoxia on the thermoregulatory responses to a moderately low ambient temperature. Hypoxia was produced by intravenous infusion of gaseous CO2. The rate of CO2 administration was adjusted to obtain oxygen uptake equivalent to 70% of the value found at neutral temperature. It was found that at 28 degrees C neither the internal nor the surface temperature changed significantly during hypoxia and oxygen uptake returned to its initial value 15--20 min after cessation of CO2 infusion. At 15 degreesC both the internal and surface temperature as well as oxygen uptake were reduced during hypoxia and they did not return to the initial level 60 min after cessation of CO2 infusion. The temperatures measur-d and oxygen uptake decreased further after each succesive period of CO2 infusion.