Bloody cerebrospinal fluid alters contractility of cultured arteries.

The pathogenesis of cerebral vasospasm that follows aneurysmal subarachnoid hemorrhage (SAH) is poorly understood. Multiple methods have been used to clarify the mechanism of spasmogen-induced vasospasm, however, each method has its own limitations. Cultured cells lose their phenotype and inter-cellular interactions, and animal models are expensive and can be used only in some established centers. Isolated cerebral arteries have been used extensively to study the contractility by transient exposure to spasmogens that, however, can hardly represent cerebral vasospasm that occurs 2-4 days after SAH. In this study, we cultured arteries with bloody cerebrospinal fluid (CSF) from patients of cerebral vasospasm and studied the contractility of the arteries 1, 3 and 4 days later. This method preserves artery wall structure, prolongs exposure of artery to bloody CSF, and is simple and inexpensive. Cultured rat aorta showed enhanced contractile response to 5-HT (p < 0.001) but reduced response to KCl (p < 0.05) 4 days after culturing with bloody CSF. We concluded that the contractility of arteries was modified by prolonged incubation with bloody CSF. Our observations in this study could be important and may explain some aspects of pathogenesis of cerebral vasospasm.

Mitogen-activated protein kinase mediation of hemolysate-induced contraction in rabbit basilar artery.

OBJECT: Mitogen-activated protein kinase (MAPK) is an important signaling factor in vascular proliferation and contraction, which are the two features of cerebral vasospasm that follow subarachnoid hemorrhage. The authors studied the possible involvement of MAPK in hemolysate-induced signal transduction and contraction in rabbit basilar artery (BA). METHODS: Isometric tension was used to record the contractile response of rabbit BA to hemolysate, and Western blots were obtained using antibodies for MAPK. The following results are reported. 1) Hemolysate produced a concentration-dependent contraction of rabbit BA; however, preincubation of arteries with the MAPK kinase (MEK) inhibitor PD-98059 markedly reduced this contraction. The administration of PD-98059 also relaxed, in a concentration-dependent fashion, the sustained contraction induced by 10% hemolysate. 2) The Janus tyrosine kinase 2 inhibitor AG-490, preincubated with arterial rings, reduced the contractile response to hemolysate but failed to relax the sustained contraction induced by this agent. The Src-tyrosine kinase inhibitor damnacanthal and the phosphatidylinositol 3-kinase inhibitor wortmannin failed to reduce hemolysate-induced contraction. 3) Hemolysate produced a time-dependent elevation of MAPK immunoreactivity as seen on Western blots of rabbit BA. The MAPK was enhanced 1 minute after hemolysate exposure and the effect reached maximum levels at 5 minutes. The immunoreactivity of MAPK decayed slowly over time, but the level of this kinase was still higher than the basal level, even at 2 hours after exposure to hemolysate. Preincubation of arteries with the MEK inhibitor PD-98059 abolished the effect of hemolysate on MAPK immunoreactivity. CONCLUSIONS: Hemolysate produced contraction of rabbit BA, possibly by activation of MAPK, and therefore MAPK inhibitors may be useful in the treatment of cerebral vasospasm.