Effect of long-term exposure of rabbits to ultraviolet radiation on the level, creation and inactivation of kinins in blood.

Experimental rabbits were exposed to ultraviolet radiation during 6 weeks once daily for 10 minutes (from a high-pressure. Hanau Q 400 mercury lamp with a Schott UG 2 T filtre and absorber of long-wave radiation using ultraviolet rays of 405--289 nm wavelength and 134 000 erg/sec/cm2 power, directed onto skin with cropped hair of the back). Under general anaesthesia with pentothal blood samples were obtained from the carotid artery in 4 groups of 8 rabbits in each group. The blood samples were taken from non-exposed control rabbits and from the experimental groups after 2, 4 and 6 weeks of exposure. In the samples the levels of free kinins in the blood, and kininogen, and the activity of kallikreins and kininases in the plasma were determined. In the irradiated animals a progressive rise of free kinins most pronounced after 6 weeks was observed, and other findings included: a fall of kininogen level particularly steep after 2 weeks, very small rise in the activity of kallikreins, and progressing reduction of the activity of kininase, particularly steep after 2 weeks.