Effect of stimulation of leukocyte chemotaxis by fMLP on white blood cell behaviour in the microcirculation of rat brain.

The role of white blood cells in acute cerebral disorders such as ischemia or stroke is still unclear. Therefore, in the present study we investigated the effects of the leukotaxin n-formyl-methionyl-leucyl-phenylalanine (fMLP) on white blood cell endothelial-cell interactions in the rat brain surface microcirculation. An improved closed cranial window technique was applied. Superfusion of fMLP in rising concentrations (10(-8) - 10(-5) M) was seen to induce rolling and adherence of leukocytes to teh endothelium of small venules. Rolling was more effectively stimulated than firm attachment. fMLP-induced vasodilation was more pronounced in arterioles than in venules. In this study it has been shown that the hydrophilic fMLP is effectively stimulating neutrophil chemotaxis across the blood-brain barrier. Further, the closed cranial window preparation is useful to analyze quantitatively properties of activated leukocytes, which may be pertinent in injury to the blood-brain barrier and induction of microcirculatory disturbances.