[Study of the effects of Alfatesin on cerebral blood flow in cats].

The cerebral haemodynamic effects of CT 1341 also called Alfatesin, an anaesthetic steroid, were studied in the cat by means of the Xenon 133 isotopic clearance method to measure the cerebral blood flow. The injection or intravenous drip of Alfatesin in animals whose arterio PCO2 was kept unchanged induced a cerebral blood flow diminution, the importance of which was proportional to the injected dose. The cerebral blood flow fall was partly due to a cerebral arterio vasoconstriction evidenced by direct observation of the cortex vessels and by a diminution of the intracranial presure. During a deep anaesthesia induced by Alfatesin with recurrent burst suppression, there was a loss of cerebral blood flow autoregulation while the CO2 cerebral vascular reactivity was maintained. This last result accounts for the increase in cerebral blood flow parallel to the hypercapnia that could be observed among animals breathing freely.