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Effect of Ultraviolet-Irradiation Overdosage on Sodium, Potassium, Calcium and Aldosterone in Plasma of Calves

BROUCEK J, GAJDOSIK D, LETKOVICOVA M, KOVALCIK K
Veterinarni Medicina 37, 1992, 365-370

Five Holstein-Friesian calves, from one sire, with prevalent black hair coat pigmentation were used in the experiment. The mean age was 33 days and the mean live weight 51 kg. The animals were exposed free running without interruption for 12 hours to an artificial ultraviolet light in the range of 280-320 nm. The mean dosis of radiation was 179. 10(-10) J/h/m. One-spot high-pressure mercury discharge lamps Tesla RVK 400 W were used as a radiation source. The dose rate was estimated from measurements by a spectral photometer with filter UG 2 for absorbtion of visible light located at the height of the back of standing calf. Blood samples were collected immediately before the beginning of treatment and after 5, 12, 24, 48 and 72 hours. The blood plasma aldosterone was measured by radioimmunoassays, the levels of sodium, potassium and calcium in blood plasma by flame spectrophotometry. Double classification variance analysis and evaluation according to the Snedecor F-test, the contrast effect test according to Duncan and regression analysis were used for statistical evaluation. Compared to the first sampling, sodium increased significantly after 5 and 12 hours of exposure (Tab. I) to 138.1 and 138.3 mmol/l, respectively. In the subsequent samplings this trend continued up to 72 hours from the beginning of irradiation (140.5 mmol/1). The potassium level did not change statistically significantly. Owing to an excessive irradiation, the calcium concentration increased significantly. The greatest oncrease occurred after 12 hours of irradiation (from 2.29 mmol/l to 2.61 mmol/l) and after 36 hours from the and of irradiation (2.70 mmol/l). The aldosterone level showed the greatest increase as early as after 5 hours of irradiation (from 8.54 ng/l to 17.22 ng/l) and 12 hours after the termination of exposure it returned to the initial level. The correlations between the irradiation doses during 5 and 12 hours of exposure and the single indices are given in Tab. II. In the case of sodium, the relations were always positive and weak, with the exception of the blood sampling after 72 hours (r = 0.726


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