[Mechanisms of pial artery responses in hypo- and hypertension].

Simultaneous study of the pial arterial responses and quantitative changes of the systemic arterial pressure, as well as of the PO2, pH and PCO2 on the brain surface, showed no correlation between the values and time of changes of the above parameters in rabbits. The vascular responses are concluded not to be caused by the direct action of either the changes of the intravascular pressure, or of the mentioned metabolites on the arterial walls, but rather to be due to another, probably nervous, feedback mechanism.