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Mitogen-activated protein kinase mediation of hemolysate-induced contraction in rabbit basilar artery
A Y Zubkov1, K Ogihara, P Tumu
1Department of Neurosurgery, University of Mississippi Medical Center, Jackson 39216-4505, USA. azubkov@neurosurgery.umsmed.edu
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.
Insights
Mitogen-activated protein kinase (MAPK) activation by hemolysate causes rabbit basilar artery contraction. MAPK kinase inhibitors significantly reduced this contraction, suggesting their therapeutic potential for cerebral vasospasm.
Area of Science:
- Vascular biology
- Neuroscience
- Pharmacology
Background:
- Cerebral vasospasm after subarachnoid hemorrhage involves vascular proliferation and contraction.
- Mitogen-activated protein kinase (MAPK) is a key signaling factor in these vascular responses.
Purpose of the Study:
- To investigate the role of MAPK in hemolysate-induced signal transduction and contraction in rabbit basilar arteries (BA).
Main Methods:
- Isometric tension recordings measured contractile responses of rabbit BA to hemolysate.
- Western blots analyzed MAPK expression using specific antibodies.
- Pharmacological inhibitors, including PD-98059 (MAPK kinase inhibitor), were used to assess pathway involvement.
Main Results:
- Hemolysate induced concentration-dependent contraction of rabbit BA.
- Preincubation with PD-98059 significantly reduced hemolysate-induced contraction and relaxed sustained contractions.
- Hemolysate exposure led to a time-dependent increase in MAPK immunoreactivity, which was abolished by PD-98059.
Conclusions:
- Hemolysate triggers contraction in rabbit BA, likely through MAPK activation.
- MAPK inhibitors show promise as a potential therapeutic strategy for treating cerebral vasospasm.