The effect of a lipid hydroperoxide of arachidonic acid on the canine basilar artery

Abstract

The in vivo spasmogenic capacity of a lipid hydroperoxide (15-hydroperoxy arachidonic acid: 15-HPAA) was studied in a chronic experiment using the dog. The 15-HPAA was injected into the cisterna magna (0.2 or 2 mg emulsified in bovine serum albumin solution). The changes in diameter of the basilar artery were followed by angiography. The morphological changes were studied by EM. The cisternal injection of 0.2 mg of 15-HPAA caused a mild constriction of the basilar artery which lasted about 7 h. The cisternal injection of 2 mg of 15-HPAA caused a biphasic constriction, the initial phase of which was a moderate narrowing lasting about 10 h. The 2nd phase started on the 2nd or the 3rd day after injection. The intensity of the arterial narrowing was more pronounced in the 2nd phase than in the 1st. The prolonged secondary constriction of the basilar artery continued until sacrifice on the 7th day after injection. EM study revealed a marked degenerative change in the endothelium and myonecrotic changes in the tunica media. The prolonged arterial constriction in the 2nd phase was invariably associated with remarkable degeneration of the endothelium. Myonecrotic changes were limited to a small number of smooth-muscle cells. Lipid peroxidation associated with lysis of the subarachnoid clot apparently is involved in the genesis of chronic vasospasm in subarachnoid hemorrhage.