The influence of ionizing irradiation (1, 2 and 4 Gy 137Cs) on both the activity of free-radical processes in plasma, formed elements and aorta wall as well as on the character of contractile vascular reactions of isolated rings of thoracic aorta and carotid artery in rabbits has been studied. The experiments were carried out on the 7th day after the whole-body irradiation. The results indicate that simultaneously with the weakening of antioxidant mechanisms both endothelium-dependent and endothelium-independent vascular wall relaxation slightly decreases after 1 Gy exposure. Noradrenaline and KCI-induced contraction is shown to increase. However, these changes are not statistically significant. Irradiation in dose of 2 and 4 Gy considerably decreases endothelium-dependent relaxation. Nitroglycerin-induced relaxation greatly diminishes, KCI- and noradrenaline-induced constriction considerably increases in these conditions. The level of activation of free-radical processes considerably increases too. Thus, already on the 7th day after irradiation significant changes in reactivity of vascular wall are developed. Radiation injures both endothelium and vascular smooth muscle cells. The free-radical processes seem to be the main cause of radiation vascular damage, so there is a pronounced correlation between the changes of vascular contractile properties and the degree of activation of these processes.
Chronic experiments on dogs with gastric fistulas were carried out to study the influence of angiotensin 1 and angiotensin 2 on pentagastrin- and histamine-induced gastric acid secretion. It was established that both angiotensins inhibited gastric acid secretion stimulated by pentagastrin but not by histamine. Comparative analysis of the effects of stimulation and inhibition of cholino- and adrenoreceptors on this inhibitory action of angiotensins suggested the mediation of angiotensin influence through the modulation of cholinergic reactions of parietal cells in the stomach.
BACKGROUND: The eosinophil granulocyte is an inflammatory cell that plays an active part in diseases such as asthma and rhinitis. This study aimed to investigate oxidative metabolism by blood eosinophils taken from allergic rhinitis patients, asthmatics, and nonallergic controls before and during the birch-pollen season. METHODS: Twenty patients with allergy to birch pollen and seasonal symptoms of rhinitis, some of whom were also asthmatic, were followed before and during the birch-pollen season in Sweden. The cells were purified using a Percoll gradient and the MACS system. Eosinophil purity in all samples was > 95%. Oxidative metabolism was measured by a chemiluminescence (CL) assay, with luminol and lucigenin acting as enhancers, and PMA, serum-treated zymosan (STZ), interleukin (IL)-5, or RANTES as stimuli. RESULTS: The allergic subjects showed reduced luminol CL when activated before the season with PMA (P = 0.040) or STZ (P = 0.0055). This was not seen during pollen exposure. STZ-activated lucigenin CL was also reduced before the season (P = 0.0027). The reduction was most evident in the group with asymptomatic rhinitis. In terms of eosinophil stimulation, IL-5 and RANTES were equally effective in allergic and nonallergic subjects, both before and during the pollen season. CONCLUSIONS: Blood eosinophils from asymptomatic allergics may have a lower capacity to produce oxygen-free radicals than eosinophils from nonallergics.