Upregulation of rho A and rho kinase messenger RNAs in the basilar artery of a rat model of subarachnoid hemorrhage

Object. Rho A, a small guanosine triphosphate-binding protein, and rho kina ses have been suggested to play an important role in the agonist-induced my ofilament Ca++ sensitization and cytoskeletal organization of smooth-muscle cells. To discover their possible roles in the prolonged contraction seen in cerebral vasospasm, the authors investigated the messenger (m)RNA expres sions of rho A and rho-associated kinases alpha and beta in the basilar art ery (BA) of a rat double cisternal blood-injection model. Methods. An experimental subarachnoid hemorrhage (SAH) was achieved in rats by twice injecting autologous arterial blood into the cisterna magna of ea ch animal. The mRNAs for rho A and rho-associated kinases alpha and beta of the rat BA were analyzed using reverse transcription-polymerase chain reac tion (RT-PCR). The cisternal blood injection induced a marked corrugation o f elastic lamina and contraction of smooth-muscle cells observed with the a id of light and transmission electron microscopy in the rat BA on Days 3, 5 , and 7. Results of the RT-PCR revealed that mRNAs for rho A and rho kinase s alpha and beta were expressed in the rat BA and that they were significan tly upregulated and reached their peaks on Day 5. Conclusions. The mRNA upregulation of these proteins indicates that activat ion of rho A/rho kinase-related signal transduction pathways is involved in the development of long-lasting contraction of cerebral arteries after SAH .