Doppler sonography to monitor flow in different cerebral arteries in the rabbit

Most of the transcranial Doppler (TCD) experimental studies on cerebral haemodynamics have been performed in the rabbit because of the similarity between its Willis circle and that of the human, but these studies have mainly been limited to the basilar artery. The present study was aimed at extending the use of TCD sonography to all other large cerebral arteries. In anaesthetised rabbits, these arteries were insonated from three different recording sites, i.e. top-cranial, suboccipital and orbital, using a two-channel pulsed Doppler device equipped with 4 and 8 MHz probes. First, discrimination between intra- and extracranial arteries was achieved through a standard 'rebreathing' test (hypercapnic-hypoxic stimulation). The distinctive blood velocity response patterns, reflecting the different extents of metabolic reactivity in intra- and extracranial territories, are described and discussed. Intracranial arteries were then identified on the basis of their response to ipsi- and contralateral common carotid artery occlusion. This procedure allowed recording from the following arteries: anterior common trunk, anterior cerebral, internal carotid, middle cerebral and basilar; the latter could be simultaneously monitored with any of the others. This study provides an experimental model allowing investigation of regional differences in the haemodynamic response to neurogenic and pharmacological stimuli.