Extracellular K+ and H+ activities in the brain cortex during and after a short period of ischaemia and arterial hypoxia.

Abstract

It is well known that cerebral blood flow increases strongly after a short period of tissue anoxia. However, the exact mechanism of the regulation is still unknown. Local H+ and K+ activities have been assumed to play an important role in the regulation of local cerebral blood flow. But recently some evidence against H and K+ as the main factors of regulation has been published (Astrup et al., 1976). As there is little direct information available about the kinetics of these ions in the brain cortex, especially with regards to local hydrogen activity, we investigated the behaviour of these ions in the brain cortex during a short period of arterial anoxia and total cerebral ischemia. Previous data were published elsewhere (Urbanics et al., 1976). Furthermore, we tried to clarify the question as to whether the redistribution of microflow which occurs during anoxia and which was described by Leniger-Follert et al. (1976) could be caused by different local kinetics of these ions. Another problem we tried to solve was whether these ions could be responsible for the rapid decrease of oxygen consumption after a few seconds of total cerebral ischaemia (see Leniger-Follert, this symposium).