In awake nonnocapnic rats, the density of the total and of the perfused capillary network was determined in 10 brain areas. The

Propofol diluted in an emulsion of medium- and long chain-triglycerides shows equivalent pharmacological properties during long-term sedation compared with its hitherto well known formulation containing long-chain triglycerides only. In addition, potential favorable effects on the plasma triglyceride profile could be found.

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Summary: The densities of perfused and existing capil laries were measured in different cortical regions of rat brains after subtemporal occlusion of the middle cerebral artery (MCA). Capillary perfusion patterns (perfused cap illaries versus nonperfused capillaries) were verified im mediately after MCA occlusion in one group of rats and I h later in a second group using fluorescent double staining of capillary morphology and plasma perfusion in identical brain sections. In addition, local cerebral blood flow (CBF) was measured in another group of rats I h after MCA occlusion using the autoradiographic iodo-[14C] antipyrine method. Although cortical CBF was decreased by up to 75% 1 h after MCA occlusion, plasma perfusion

Summary:To assess the reliability of fluorescence meth ods for a quantitative staining of brain capillaries, three different immunohistochemical fluorescent markers were used in the rat brain. Staining of the basement membrane by antibodies directed against fibronectin was compared, in the same brain section, with simultaneous staining of the vascular endothelium constituents nonmuscle myosin or von Willebrand factor (factor VIII). These stainings all resulted in identical patterns, which demonstrates their suitability for capillary staining in the brain. It has beenIn a previous study (Gobel et aI., 1990), we have postulated a continuous perfusion of all capillaries in the brains of conscious rats. The fluorescent mi croscopical method as used in this study has been criticized since higher capillary counts were mea sured than have been reported by groups that used light microscopical histochemical methods (Weiss, 1989; Kikano et aI., 1989; Anwar et aI., 1990). The discrepancy was ascribed to the fixation procedure employed in our experiments, which "causes changes in the FITC label which may cause clump ing or movement to noncapillary areas" (Weiss, 1988). It was the aim of the present study to validate the use of fluorescent markers of brain capillaries and to exclude the possibility of artifacts caused by the staining procedure. MATERIALS AND METHODSThe experiments were performed on male Sprague Dawley rats weighing 270-350 g.Received April 25, 1991; revised June 27, 1991; accepted July I, 1991.Address correspondence and reprint requests to Prof. Dr. w. Kuschinsky at Physiologisches Institut der Universitat Heidel berg, 1m Neuenheimer Feld 326, W-6900 Heidelberg, F.R.G.Abbreviations used: DTAF , 4.5-[(4,6-dichlorothriazin-2-yl)aminolfluorescein; PBS, phosphate-buffered saline; TRITe, tetramethylrhodamine B isothiocyanate. 347claimed that fixation of the tissue results in the appear ance of spurious capillary spots. Such a fixation artifact could be excluded using nonmuscle myosin staining. These results validate the methods of quantitative fluo rescent microscopical staining of capillary morphology in the brain and therefore support our concept of a contin uous perfusion of all capillaries in the brains of conscious rats. Key Words: Brain capillaries-Capillary perfusion Fibronectin-Indirect immunofluorescence-Nonmuscle myosin-von Wille brand factor. Double staining of capillary morphologyAfter decapitation, the brains of nine rats were pro cessed as described previously (Gobel et aI., 1990, Method 3). Fixation in pure acetone was performed for 30 s. The sections were overlaid with 70 j.Ll of the first of four antibodies (AI or Bl), and then they were incubated in a humid chamber at room temperature for 30 min. There after, the sections were washed three times in phosphate buffered saline (PBS) for 5 min. The margins were wiped dry, and the sections were overlaid with the second an tibody (A2 or B2). This procedure was repeated twice (A3 or B3, A4 or B4). The following sequence (1-4) of the staining steps yi...