Marilyn J. Cipolla
>thank you for your comments. Even though we used fresh isolated smooth muscle cells from rat basilar artery and used cells within 4 hrs, I agree that isolated cells are different from these in the vessel wall. Another side of the issue is cerebral vasospasm takes days to develop and calcium studies are done in several min. The acute effect may not be the true response leads to a prolonged contraction. Incubating arteries in hemoglobin for days may produce contraction not reproducible by in vitro conditions. The calcium dependence of vasospasm is another issue people disagree. Some in vivo studies showed that the resting calcium during spasm was actually lower than normal arteries, even though all studies using cultures or fresh isolation demonstrate a calcium response to spasmgenes. PKC is an aspect people interested and some of PKC-induced contraction is calcium independent. As you know that PKC leads to the activation of tyrosine kinasesa and further MAPK. These two "new" fields are our current interests. Tyrosine and MAP kinase play roles in proliferation as well as contraction (by caldesmon), and proliferation is another aspect of vasospasm.
I think that the time course of vasospasm, being several days, is really interesting and probably key to discovering what factors play a role. I wonder how the cells within the vascular wall are altered phenotypically during this time period. I guess if you knew that then your work would be complete!