[A study of pial vessel behavior on superior sagittal sinus and cortical venous occlusion]

In cerebral circulation, it is suspected that neurogenic or myogenic mechanism protect blood vessel and blood-brain barrier during sudden increase in arterial pressure. To discriminate metabolic mechanism from neurogenic and myogenic mechanism, complete cerebral venous occlusion model of cat was used to obtain high venous pressure. In twenty-one anesthetized cats, 0.3 ml of cyanoacrylate were injected into anterior part of SSS to occlude SSS and cortical vein. Diameter of pial vessels and ICP were measured through the cranial window. An average of ICP was 6.7 +/- 1.8 mmHg before occlusion. 5 minutes after occlusion ICP was elevated to an average of 10.4 +/- 4.8 mmHg. Finally, ICP increased over 20 mmHg in nine animals. All pial vein dilated immediately after injection of cyanoacrylate and the dilatation rate was 2-55%. Pial arteriole between 50 microns and 100 microns in diameter was observed. In early stages, 2-24% contraction of arteriole were observed in fifteen animals and 2-16% dilatation were observed in six animals. In later stages, 1-87% dilatation of arteriole were observed in ten cats. Ten of twelve ( 83%) cases with ICP under 20 mmHg showed contraction of pial arteriole. Eight of nine (89%) cases with ICP over 20 mmHg showed dilatation of pial arteriole. In addition, the elevation of ICP and the dilatation of pial arteriole were observed simultaneously. Correlation between ICP and arterial diameter is obvious. The dominant mechanism of cerebral blood flow control is metabolic, not neurogenic and myogenic. Increase of ICP, dilatation of vein and dilatation of artery with increasing ICP are consistent with the theory.(ABSTRACT TRUNCATED AT 250 WORDS)