Abstract
It has been revealed that the large cerebral artery adjacent to a ruptured aneurysm has not only a functional contraction but also various pathological changes of the blood vessel in the stage of late spasm. We reported previously that when the narrowing artery was recognized on a cerebral angiogram in patients with ruptured aneurysm, its histological change could be estimated by studying the appearance and frequency of electrical discharges recorded from the narrowing artery after clipping of the aneurysm.
In this study, we recorded simultaneously the isometric contraction and electrical discharge from a ring-cut bovine middle cerebral artery in organ bath by administration of serotonin and incubated bovine blood. Furthermore, we studied the relationship between the frequency of an electrical discharge induced by incubated blood and the pathological change of vascular smooth muscle after making the vessel contract continuously in incubated blood for 5 minutes, 3 hours and 6 hours.
The result was as follows; Vascular contraction induced by serotonin and incubated blood followed an electrical discharge recorded from the vascular wall. After 5 minutes of overloading of incubated blood on the vessel, the electrical discharge showed burst appearance and the histological findings of the vascular smooth muscle was considered to be nearly normal. After 3 hours, the electrical discharge showed sporadic appearance and the histological picture had partial degenerative change of vascular smooth muscle. After 6 hours, the electrical discharge was seldom or never detected and the histological picture had a diffuse degenerative change of vascular smooth muscle.
From the result of the experimental study, we were able to determine that the electrical discharge recorded from the vascular wall in patients with ruptured aneurysm is derived from vascular smooth muscle and its appearance could be regarded as the indicator of the functional reversibility of cerebral vasospasm.
