Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
Board

We investigated the involvement of protein tyrosine kinase activity in hemolysate-mediated signal transduction in cerebral smooth muscle cells. Erythrocyte lysate induced, dose-dependently, Ca2+ release from intracellular stores and Ca2+ entry in rat basilar smooth muscle cells. Preincubation of cells with tyrosine kinase inhibitors genistein, tyrphostin 51, but not tyrphostin A1, an inactive analog of tyrphostin, reduced remarkably the [Ca2+]i response, both Ca2+ release and Ca2+ entry, to erythrocyte lysate. Erythrocyte lysate was then fractionated into two parts, molecules smaller or larger 10kDa. Small molecules induced a similar [Ca2+]i elevation to that of unfractionated erythrocyte lysate and large molecules produced only a weak response. Tyrosine kinase inhibitors attenuated the [Ca2+]i response to both fractions. In western blotting, erythrocyte lysate induced an increase in the level of tyrosine phosphorylation of two proteins, approximately 70 and 110 kDa, in the cultured rat basilar and rat thoracic aorta smooth muscle cells. We concluded that protein tyrosine kinase medicated the effect of erythrocyte lysate on [Ca2+]i and tyrosine phosphorylation may play a role in cerebral vasospasm.

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Presentation Number SAs. iwabuchi0452
Keywords: tyrosine kinase, vasospasm, smooth muscle cell, erythrocyte lysate, [Ca2+]i