No abstract

The aim of the present study was to measure the therapeutic effects of bradykinin antagonists on lesion volume and brain swelling induced by cold injury in the parietal cortex of rat and mouse, respectively. Cold lesion was induced by application of a precooled (-78 degrees C) copper cylinder (3 mm diameter) to the intact dura of rat and mouse for 6 and 30 sec, respectively. At 24 h after the injury, the brains were removed and lesion volume was determined by the triphenyltetrazolium chloride method in rats. In the mouse, brain swelling was expressed as percentage increase in weight of the injured hemisphere which is compared to the contralateral side. After a subcutaneous priming dose of 18 microg/kg, a 1-h pretreatment and 24-h posttreatment using osmotic minipumps (300 ng/kg x min) was applied. Hoe140, a bradykinin receptor 2 antagonist, revealed a 19% reduction of lesion volume (p < 0.05) in the rat and a 14% diminution of brain swelling (p < 0.05) in the mouse. In contrast, the bradykinin receptor 1 antagonist, B 9858, had no effect on lesion volume compared to sham treated rats. When B 9858 was given in combination with Hoe140, a significant reduction in lesion volume was seen which was equivalent to and not different from that seen with Hoe140 alone in the rat. We conclude that brain injury after cold lesion is partially mediated by bradykinin and can be successfully treated with B2 antagonists.

The aim of the present study was to investigate whether endothelin-1 (ET-1) in cerebral arteries is inhibited by the new, non-peptidergic ET(A) receptor antagonist Ro 61-1790 and, if it is, whether that inhibition reduces the lesion volume induced by cold injury in the parietal cortex. In vitro experiments were performed by measuring the isometric contractions of the rat middle cerebral and basilar arteries. A cold lesion was induced in vivo by the application of a pre-cooled (-78 degrees C) copper cylinder (diameter 3 mm) to the intact dura of rats for 6 s. After 24 h, lesion volume was determined by the triphenyltetrazolium method. In vitro, ET-1 (10(-12) - 3x10(-7) M) caused a dose-dependent contraction under resting conditions in the middle cerebral and basilar arteries of control rats. Ro 61-1790 (3x10(-9) M, 10(-7) M) shifted the concentration-effect curves for ET-1 in a parallel fashion (Emax unaltered). Post-treatment with Ro 61-1790 (10(-7)-10(-5) M) also inhibited the prior contraction elicited by ET-1 (3x10(-9) M) significantly. In vitro ET-1 application 3 h after the intracerebroventricular in vivo administration of Ro 61-1790 showed that the antagonist had reached the arteries and was bound to their ET(A) receptors. Intracerebroventricular pre-treatment of Ro 61-1790 reduced significantly the lesion volume by 23% after the injury. We conclude that ET-1 is involved in the development of secondary brain damage and that intracerebroventricular treatment with Ro 61-1790 reduces the size of the brain lesion caused by cold injury.