CHANGES IN CORTICAL DC POTENTIAL DURING COMPLETE AND INCOMPLETE BRAIN ISCHEMIA

In isolated dog head preparations the d.c. potential of the convexity of the brain (gyrus lateralis) with respect to the surface of os frontale was measured in complete and incomplete ischemia of the brain. During complete ischemia an initial positivity, reaching a maximum of 1.5 to 2 mV after 1.5 to 2.75 min, is followed by a negative shift. The negativity reaches a steady state of 6.5 mV on an average 3 to 8 min after onset of the ischemia. After termination of a complete ischemia a transitory positivity is followed by a longer lasting negativity. In incomplete ischemia the d.c. potential turns negative, when the blood pressure has decreased to 80 to 40 mm Hg. It is assumed that the negative shift begins at the critical blood pressure of the brain. © 1968 Springer-Verlag.