Acute Arterial Hypertension and the Blood-Brain Barrier: An Experimental Study in Dogs

A sudden large arterial blood pressure increase induced by Aramine has been found to cause blood-brain barrier (BBB) damage, while a stepwise rise in pressure to the same total increment leaves the BBB intact. The interpretation was that during the slow rise the autoregulatory mechanism was given time enough to prevent the pressure increase from being transmitted to the small vessels to the same extent as’with the sudden blood pressure rise (3). The pressure-flow relation in nonpharmacologically induced arterial hypertension shows autoregulation up to a certain limit, which at low or ordinary flow levels is usually found at a mean arterial blood pressure around 200 mm Hg. The higher the normotensive flow level was, the lower was the upper limit for autoregulation. Above the autoregulatory pressure limit a flow increase occurred (1).