Physiological and morphometric analysis of the microcirculation of the cerebral cortex under acute vasospasm

Tissue PO2 measurements with microelectrodes and morphometric analysis of capillaries were combined to investigate microcirculatory changes in cat brains subjected to vasospasm (superfusion of platelet-poor plasma). It can be shown that vasospasm leads to marked tissue hypoxia as illustrated by a drastic shift in the PO2 distribution within the cortical tissue. Morphological measurements of various capillary parameters demonstrated a marked constriction in precapillary segments as well as in capillaries themselves. This decrease in perfusion of the capillary bed could not be compensated for by increasing the systemic arterial blood pressure. Our results demonstrate that, even with a platelet-poor fraction, marked changes occur on a microcirculatory level in the cerebral cortex with vasospasm, which may not be detected by macroscopic techniques.