Endolymphatic sac tumors in patients with and without von Hippel—Lindau disease: the role of genetic mutation, von Hippel—Lindau protein, and hypoxia inducible factor-1α expression

2004 ◽  
Vol 100 (3) ◽  
pp. 488-497 ◽  
Author(s):  
Randy L. Jensen ◽  
David Gillespie ◽  
Paul House ◽  
Lester Layfield ◽  
Clough Shelton
Keyword(s):  
Gene Expression ◽  
Tumor Tissue ◽  
Hypoxia Inducible Factor ◽  
Endolymphatic Sac ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Ca Ix ◽  
Vhl Disease ◽  
Fine Print

Object. Endolymphatic sac (ELS) tumors are low-grade malignancies of the temporal bone that are associated with von Hippel—Lindau (VHL) disease but can also occur sporadically. The VHL gene product VHL protein is important in the regulation of hypoxia inducible factor (HIF)-1α, which controls expression of molecules that are important in angiogenesis and cell metabolism. In this study the authors examine the role of VHL and HIF-1 in ELS tumors. Methods. The ELS tumors from three patients were examined using the following method: DNA from tumor tissue was isolated, amplified by polymerase chain reaction and the VHL gene sequence was compared with the known wild-type sequence. Loss of heterozygosity (LOH) studies were performed to confirm the sequencing data. Immunohistochemical evaluation for VHL, HIF-1α, vascular endothelial growth factor (VEGF), and carbonic anhydrase IX (CA IX) was performed. Snap-frozen tumor tissue was examined using Western blot and HIF-1 immunoassays for HIF-1α and VHL expression. Two patients had sporadic ELS tumors and the other one suffered from VHL disease. Results of VHL gene sequencing were normal in the tissue derived from the sporadic ELS tumors. The ELS tumor, pheochromocytoma, and spinal hemangioblastoma were heterozygous for the same C-to-A transversion found in the germline carried by the patient with VHL disease. No LOH was detected in the tumor tissue obtained in the patient with VHL disease. Expression of HIF-1α, VEGF, and CA IX evaluated using immunohistochemical studies was elevated in the VHL-associated tumors. Nevertheless, Western blots and immunoassays for HIF-1α did not show elevated expression in these tumors. Conclusions. The sporadic and VHL disease—associated ELS tumors in this study had normal VHL-mediated HIF-1 regulation. This is a result of normal VHL gene expression in the case of the sporadic ELS tumor. In the VHL-associated ELS tumor, this is due to one normal copy of the VHL gene and adequate VHL gene expression.

Endolymphatic sac tumors in von Hippel—Lindau disease

2004 ◽  
Vol 100 (3) ◽  
pp. 480-487 ◽  
Author(s):  
Daniel Choo ◽  
Lawrence Shotland ◽  
Maryann Mastroianni ◽  
Gladys Glenn ◽  
Carter van Waes ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Inner Ear ◽  
Family Members ◽  
Magnetic Resonance Images ◽  
Endolymphatic Sac ◽  
Specific Gene ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Vhl Disease ◽  
Fine Print

Object. Von Hippel—Lindau (VHL) disease is a hereditary multiple-neoplasia syndrome mapping to chromosome 3p25–26. Endolymphatic sac (ELS) tumors have been identified as a neoplastic manifestation of VHL disease. The purpose of this study was to evaluate comprehensively the natural history of inner ear disease in a large population of patients with confirmed or suspected VHL disease and to correlate the clinical features with the VHL genotype. Methods. The authors collated and analyzed clinical and genotypic data obtained in patients enrolled in an Institutional Review Board—approved protocol in which families and individuals affected by VHL disease were studied. These data included results from multidisciplinary history workups and physical examinations, imaging studies, and a battery of audiological tests. One hundred seventy-five patients were enrolled in the study, 129 with confirmed VHL disease and 46 of their family members in whom test results for VHL disease were negative and who served as controls. Twenty-one patients had ELS tumors that were evident on magnetic resonance images; three of them had bilateral ELS lesions. Hearing loss, often sudden in onset and severe to profound in nature, vestibulopathy, aural fullness, and tinnitus represented the primary symptoms of ELS tumor. Distinct patterns of auditory and vestibular dysfunction occurred at different stages of the disease. Phenotypic data showed that 17 of 21 patients with ELS tumors did not have pheochromocytomas, whereas all had VHL disease affecting the kidney, all but two had VHL disease affecting the central nervous system, and all but one had disease affecting the pancreas. Genotyping revealed 10 rearrangements (partial deletions), eight single bp substitutions, and one 3-bp insertion. Although there was no difference in the incidence of hearing loss between populations, symptoms of imbalance and aural fullness were more common in patients with VHL disease but without imaging evidence of ELS tumor than they were in family members who did not have VHL disease (p < 0.01). Conclusions. Endolymphatic sac tumors are frequently associated with VHL disease. Symptoms of disequilibrium or aural fullness in patients with VHL disease may be an early indication of endolymphatic dysfunction. Patients with VHL disease provide a unique opportunity to examine the effects of specific gene mutations and a discrete neoplastic process on the human inner ear. The study of ELS tumors in this group also provides a pathological model of ELS function and supplies evidence for a role of the ELS in clinical Ménière-like disease(s).

Tumors of the endolymphatic sac in patients with von Hippel—Lindau disease: implications for their natural history, diagnosis, and treatment

2005 ◽  
Vol 102 (3) ◽  
pp. 503-512 ◽  
Author(s):  
H. Jeffrey Kim ◽  
John A. Butman ◽  
Carmen Brewer ◽  
Christopher Zalewski ◽  
Alexander O. Vortmeyer ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Natural History ◽  
Tumor Resection ◽  
Endolymphatic Sac ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Cranial Nerve Dysfunction ◽  
Vestibular Symptoms ◽  
Vhl Disease ◽  
Fine Print

Object. Endolymphatic sac tumors (ELSTs), which often are associated with von Hippel—Lindau (VHL) disease, cause irreversible hearing loss and vestibulopathy. Clinical and imaging surveillance protocols provide new insights into the natural history, mechanisms of symptom formation, and indications for the treatment of ELSTs. To clarify the uncertainties associated with the pathophysiology and treatment of ELSTs, the authors describe a series of patients with VHL disease in whom serial examinations recorded the development of ELSTs. Methods. Patients with VHL disease were included if serial clinical and imaging studies captured the development of ELSTs, and the patients underwent tumor resection. The patients' clinical, audiological, and imaging characteristics as well as their operative results were analyzed. Five consecutive patients (three men and two women) with a mean age at surgery of 34.8 years and a follow-up period of 6 to 18 months were included in this study. Audiovestibular symptoms were present in three patients before a tumor was evident on neuroimaging. Imaging evidence of an intralabyrinthine hemorrhage coincided with a loss of hearing in three patients. Successful resection of the ELSTs was accomplished by performing a retrolabyrinthine posterior petrosectomy (RLPP). Hearing stabilized and vestibular symptoms resolved after surgery in all patients. No patient has experienced a recurrence. Conclusions. Audiovestibular symptoms, including hearing loss, in patients with VHL disease can be the result of microscopic ELSTs. Once an ELST has been detected, it can be completely resected via an RLPP with preservation of hearing and amelioration of vestibular symptoms. Early detection and surgical treatment of small ELSTs, when hearing is still present, should reduce the incidence and severity of hearing loss, tinnitus, vertigo, and cranial nerve dysfunction, which are associated with these tumors.

Surgical management of spinal cord hemangioblastomas in patients with von Hippel—Lindau disease

2003 ◽  
Vol 98 (1) ◽  
pp. 106-116 ◽  
Author(s):  
Russell R. Lonser ◽  
Robert J. Weil ◽  
John E. Wanebo ◽  
Hetty L. Devroom ◽  
Edward H. Oldfield
Keyword(s):  
Spinal Cord ◽  
Surgical Management ◽  
Postoperative Outcome ◽  
Tumor Location ◽  
Neurological Dysfunction ◽  
Autosomal Dominant Disorder ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Vhl Disease ◽  
Fine Print

Object. Von Hippel—Lindau (VHL) disease is an autosomal-dominant disorder frequently associated with hemangioblastomas of the spinal cord. Because of the slow progression, protean nature, and high frequency of multiple spinal hemangioblastomas associated with VHL disease, the surgical management of these lesions is complex. Because prior reports have not identified the factors that predict which patients with spinal cord hemangioblastomas need surgery or what outcomes of this procedure should be expected, the authors have reviewed a series of patients with VHL disease who underwent resection of spinal hemangioblastomas at a single institution to identify features that might guide surgical management of these patients. Methods. Forty-four consecutive patients with VHL disease (26 men and 18 women) who underwent 55 operations with resection of 86 spinal cord hemangioblastomas (mean age at surgery 34 years; range 20–58 years) at the National Institutes of Health were included in this study (mean clinical follow up 44 months). Patient examination, review of hospital charts, operative findings, and magnetic resonance imaging studies were used to analyze surgical management and its outcome. To evaluate the clinical course, clinical grades were assigned to patients before and after surgery. Preoperative neurological status, tumor size, and tumor location were predictive of postoperative outcome. Patients with no or minimal preoperative neurological dysfunction, with lesions smaller than 500 mm3, and with dorsal lesions were more likely to have no or minimal neurological impairment. Syrinx resolution was the result of tumor removal and was not influenced by whether the syrinx cavity was entered. Conclusions. Spinal cord hemangioblastomas can be safely removed in the majority of patients with VHL disease. Generally in these patients, hemangioblastomas of the spinal cord should be removed when they produce symptoms or signs.

The natural history of hemangioblastomas of the central nervous system in patients with von Hippel—Lindau disease

2003 ◽  
Vol 98 (1) ◽  
pp. 82-94 ◽  
Author(s):  
John E. Wanebo ◽  
Russell R. Lonser ◽  
Gladys M. Glenn ◽  
Edward H. Oldfield
Keyword(s):  
Spinal Cord ◽  
Natural History ◽  
Mass Effect ◽  
Content Type ◽  
Von Hippel Lindau ◽  
History Of ◽  
The Central Nervous System ◽  
Brainstem Tumors ◽  
Vhl Disease ◽  
Fine Print

Object. The goals of this study were to define the natural history and growth pattern of hemangioblastomas of the central nervous system (CNS) that are associated with von Hippel—Lindau (VHL) disease and to correlate features of hemangioblastomas that are associated with the development of symptoms and the need for treatment. Methods. The authors reviewed serial magnetic resonance images and clinical histories of 160 consecutive patients with VHL disease who harbored CNS hemangioblastomas and serially measured the volumes of tumors and associated cysts. Six hundred fifty-five hemangioblastomas were identified in the cerebellum (250 tumors), brainstem (64 tumors, all of which were located in the posterior medulla oblongata), spinal cord (331 tumors, 96% of which were located in the posterior half of spinal cord), and the supratentorial brain (10 tumors). The symptoms were related to a mass effect. A serial increase in hemangioblastoma size was observed in cerebellar, brainstem, and spinal cord tumors as patients progressed from being asymptomatic to symptomatic and requiring surgery (p < 0.0001). Twenty-one (72%) of 29 symptom-producing cerebellar tumors had an associated cyst, whereas only 28 (13%) of 221 nonsymptomatic cerebellar tumors had tumor-associated cysts (p < 0.0001). Nine (75%) of 12 symptomatic brainstem tumors had associated cysts, compared with only four (8%) of 52 nonsymptomatic brainstem lesions (p < 0.0001). By the time the symptoms appeared and surgery was required, the cyst was larger than the causative tumor; cerebellar and brainstem cysts measured 34 and 19 times the size of their associated tumors at surgery, respectively. Ninety-five percent of symptom-producing spinal hemangioblastomas were associated with syringomyelia. The clinical circumstance was dynamic. Among the 88 patients who had undergone serial imaging for 6 months or longer (median 32 months), 164 (44%) of 373 hemangioblastomas and 37 (67%) of 55 tumor-associated cysts enlarged. No tumors or cysts spontaneously diminished in size. Symptomatic cerebellar and brainstem tumors grew at rates six and nine times greater, respectively, than asymptomatic tumors in the same regions. Cysts enlarged seven (cerebellum) and 15 (brainstem) times faster than the hemangioblastomas causing them. Hemangioblastomas frequently demonstrated a pattern of growth in which they would enlarge for a period of time (growth phase) and then stabilize in a period of arrested growth (quiescent phase). Of 69 patients with documented tumor growth, 18 (26%) harbored tumors with at least two growth phases. Of 160 patients with hemangioblastomas, 34 patients (median follow up 51 months) were found to have 115 new hemangioblastomas and 15 patients new tumor-associated cysts. Conclusions. In this study the authors define the natural history of CNS hemangioblastomas associated with VHL disease. Not only were cysts commonly associated with cerebellar, brainstem, and spinal hemangioblastomas, the pace of enlargement was much faster for cysts than for hemangioblastomas. By the time symptoms appeared, the majority of mass effect—producing symptoms derived from the cyst, rather than from the tumor causing the cyst. These tumors often have multiple periods of tumor growth separated by periods of arrested growth, and many untreated tumors may remain the same size for several years. These characteristics must be considered when determining the optimal timing of screening for individual patients and for evaluating the timing and results of treatment.

Comparison of anterior and posterior surgical approaches in the treatment of ventral spinal hemangioblastomas in patients with von Hippel—Lindau disease

2003 ◽  
Vol 98 (1) ◽  
pp. 117-124 ◽  
Author(s):  
Ryszard M. Pluta ◽  
Brian Iuliano ◽  
Hetty L. Devroom ◽  
Tung Nguyen ◽  
Edward H. Oldfield
Keyword(s):  
Spinal Cord ◽  
Anterior Approach ◽  
Posterior Approach ◽  
Long Term Results ◽  
Surgical Approaches ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Vhl Disease ◽  
Ventral Spinal Cord ◽  
Fine Print

Object. Von Hippel—Lindau (VHL) disease is an autosomal-dominant neoplastic syndrome with manifestations in multiple organs, which is evoked by the deletion or mutation of a tumor suppressor gene on chromosome 3p25. Spinal hemangioblastomas (40% of VHL disease—associated lesions of the central nervous system) arise predominantly in the posterior aspect of the spinal cord and are often associated with an intraspinal cyst. Rarely, the tumor develops in the anterior aspect of the spinal cord. Ventral spinal hemangioblastomas are a surgical challenge because of difficult access and because vessels feeding the tumor originate from the anterior spinal artery. The goal of this study was to clarify whether an anterior or posterior surgical approach is better for management of hemangioblastomas of the ventral spinal cord. Methods. The authors performed a retrospective analysis of clinical outcomes and findings on magnetic resonance (MR) imaging studies in eight patients (two women and six men with a mean age of 34 ± 15 years) who underwent resection of ventral spinal hemangioblastomas (nine tumors: five cervical and four thoracic). Two surgical approaches were used to resect these tumors. A posterior approach was selected to treat five patients (laminectomy and posterior myelotomy in four patients and the posterolateral approach in one patient); an anterior approach (corpectomy and arthrodesis) was selected to treat the remaining three patients. Immediately after surgery, the ability to ambulate remained unchanged in patients in whom an anterior approach had been performed, but deteriorated significantly in patients in whom a posterior approach had been used, because of motor weakness (four of five patients) and/or proprioceptive sensory loss (three of five patients). This difference in ambulation, despite significant improvements over time among patients in the posterior access group, remained significant 6 months after surgery. In all cases, MR images revealed complete resection of the tumor and in five patients significant or complete resolution of the intramedullary cyst was demonstrated (present in six of eight patients). Conclusions. The outcomes of these eight patients with hemangioblastomas of the ventral spinal cord indicate that both immediate and long-term results are better when an anterior approach is selected for resection.

Surgical management of brainstem hemangioblastomas in patients with von Hippel—Lindau disease

2003 ◽  
Vol 98 (1) ◽  
pp. 95-105 ◽  
Author(s):  
Robert J. Weil ◽  
Russell R. Lonser ◽  
Hetty L. Devroom ◽  
John E. Wanebo ◽  
Edward H. Oldfield
Keyword(s):  
Magnetic Resonance ◽  
Preoperative Evaluation ◽  
Magnetic Resonance Images ◽  
Long Term Outcome ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Vhl Disease ◽  
Fine Print

Object. Hemangioblastomas of the brainstem constitute 5 to 10% of central nervous system (CNS) tumors in patients with von Hippel—Lindau (VHL) disease. At present, optimal management of brainstem hemangioblastomas associated with VHL disease is incompletely defined. In an attempt to clarify some of the uncertainty about the operative treatment of these lesions and its outcome, the authors reviewed all cases of VHL disease in which resection of brainstem hemangioblastomas was performed at the National Institutes of Health during a 10-year period. Methods. Twelve consecutive patients with VHL disease (six male and six female patients [mean age 31.7 ± 9 years; range 15–46 years]) who underwent 13 operations to remove 17 brainstem hemangioblastomas were included in this study (mean follow-up period, 88.4 ± 37.4 months; range 37–144 months). Serial examinations, hospital charts, magnetic resonance images, and operative records were reviewed. To evaluate clinical course, clinical grades were assigned to each patient before and after surgery. Preoperative neurological function was the best predictor of long-term outcome. In addition, patients who underwent CNS surgeries for hemangioblastomas were more likely to improve or to remain neurologically stable. Tumor or cyst size, the presence of a cyst, or the location of the tumor (intramedullary, extramedullary, or mixed; posterior medullary, obex, or lateral) did not affect outcome. No patient was neurologically worse after brainstem surgery. At long-term follow-up review (mean 88.4 months), only one patient had declined neurologically and this was due to the cumulative neurological effects caused by eight additional hemangioblastomas of the spinal cord and their surgical treatment. Conclusions. Brainstem hemangioblastomas in patients with VHL disease can be removed safely; they generally should be resected when they become symptomatic or when the tumor has reached a size such that further growth will increase the risks associated with surgery, or in the presence of an enlarging cyst. Magnetic resonance imaging is usually sufficient for preoperative evaluation and presurgical embolization is unnecessary. The goal of surgery is complete resection of the lesion before the patient experiences a disabling neurological deficit.

Coexpression of erythropoietin and its receptor in endolymphatic sac tumors

2005 ◽  
Vol 103 (2) ◽  
pp. 284-288 ◽  
Author(s):  
Timothy W. A. Vogel ◽  
Alexander O. Vortmeyer ◽  
Irina A. Lubensky ◽  
Youn-Soo Lee ◽  
Makoto Furuta ◽  
...  
Keyword(s):  
Immunohistochemical Analysis ◽  
Endolymphatic Sac ◽  
Organ Distribution ◽  
Cell Of Origin ◽  
Endolymphatic Sac Tumor ◽  
Content Type ◽  
Gene Deficiency ◽  
Vhl Disease ◽  
Associated Tumors ◽  
Fine Print

Object. Von Hippel—Lindau (VHL) disease is characterized by multiple tumors in specific organs. The cell of origin and the reason for the particular organ distribution of the tumors remains unknown. Endolymphatic sac tumor (ELST) is one of the lesions associated with VHL disease. Data from previous studies of VHL disease—associated hemangioblastomas (HBs) and renal cell carcinomas (RCCs) have indicated that VHL gene deficiency causes coexpression of erythropoietin (Epo) and its receptor (Epo-R), which facilitates tumor growth. Methods. The authors studied ELSTs from five patients with VHL germline mutations. Analysis of the five ELST samples revealed loss of the wild-type allele, consistent with Knudson's two-hit hypothesis for tumorigenesis. All five ELST specimens were characterized microscopically and by immunohistochemical analysis. Coexpression of Epo and Epo-R was found in all five tumors on immunohistochemical studies and confirmed through reverse transcription—polymerase chain reaction and Western blot analysis. Conclusions. Expression of Epo appears to be a result of VHL gene deficiency, whereas the simultaneous coexpression of Epo-R may reflect a developmental mechanism of tumorigenesis. Coexpression of Epo and Epo-R in ELSTs together with the morphological and genetic similarities of these lesions with other VHL disease—associated tumors indicates that VHL disease—associated tumors in different organs share common pathogenetic pathways.

Spinal hemangioblastoma containing metastatic renal cell carcinoma in von Hippel—Lindau disease

2005 ◽  
Vol 3 (6) ◽  
pp. 495-500 ◽  
Author(s):  
Meric A. Altinoz ◽  
Carlo Santaguida ◽  
Marie-Christine Guiot ◽  
Rolando F. Del Maestro
Keyword(s):  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Metastatic Renal Cell Carcinoma ◽  
Renal Cell ◽  
Electron Microscopic ◽  
Content Type ◽  
Von Hippel Lindau ◽  
Spinal Hemangioblastoma ◽  
Vhl Disease ◽  
Fine Print

✓ The authors describe the case of a patient with von Hippel—Lindau (VHL) disease in which a spinal hemangioblastoma contained metastatic renal cell carcinoma (RCC). The literature on tumor-to-tumor metastasis associated with VHL disease of the central nervous system (CNS) is reviewed. Midthoracic back pain developed in this 43-year-old man with a left-sided radicular component 2 years after he underwent resection of a left RCC. Radiological findings demonstrated a T6–7 intradural intramedullary lesion. A T5–8 laminectomy and gross-total resection of the spinal cord mass were performed. Light and electron microscopic examination showed features of hemangioblastoma, which contained metastatic foci of RCC. Genetic analysis demonstrated the presence of a deleting mutation in the first exon (nt. 394–406) of the VHL locus, truncating 16 amino acids (N61–77) from the first beta sheet in the VHL protein. A review of the literature revealed that RCC-to-CNS hemangioblastoma is the second most common donor—recipient tumor association among the tumor-to-tumor metastases.

scholarly journals Inactivation of the Arylhydrocarbon Receptor Nuclear Translocator (Arnt) Suppresses von Hippel-Lindau Disease-Associated Vascular Tumors in Mice

2005 ◽  
Vol 25 (8) ◽  
pp. 3163-3172 ◽  
Author(s):  
Erinn B. Rankin ◽  
Debra F. Higgins ◽  
Jacqueline A. Walisser ◽  
Randall S. Johnson ◽  
Christopher A. Bradfield ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Germ Line ◽  
Hypoxia Inducible Factor ◽  
Suppressor Gene ◽  
Vascular Tumors ◽  
Von Hippel Lindau ◽  
Von Hippel Lindau Disease ◽  
Arylhydrocarbon Receptor ◽  
Vhl Disease ◽  
Endothelial Growth Factor

ABSTRACT Patients with germ line mutations in the VHL tumor suppressor gene are predisposed to the development of highly vascularized tumors within multiple tissues. Loss of pVHL results in constitutive activation of the transcription factors HIF-1 and HIF-2, whose relative contributions to the pathogenesis of the VHL phenotype have yet to be defined. In order to examine the role of HIF in von Hippel-Lindau (VHL)-associated vascular tumorigenesis, we utilized Cre-loxP-mediated recombination to inactivate hypoxia-inducible factor-1α (Hif-1α) and arylhydrocarbon receptor nuclear translocator (Arnt) genes in a VHL mouse model of cavernous liver hemangiomas and polycythemia. Deletion of Hif-1α did not affect the development of vascular tumors and polycythemia, nor did it suppress the increased expression of vascular endothelial growth factor (Vegf) and erythropoietin (Epo). In contrast, phosphoglycerokinase (Pgk) expression was substantially decreased, providing evidence for target gene-dependent functional redundancy between different Hif transcription factors. Inactivation of Arnt completely suppressed the development of hemangiomas, polycythemia, and Hif-induced gene expression. Here, we demonstrate genetically that the development of VHL-associated vascular tumors in the liver depends on functional ARNT. Furthermore, we provide evidence that individual HIF transcription factors may play distinct roles in the development of specific VHL disease manifestations.

scholarly journals Direct evidence for a key role of protein kinase C in the development of vasospasm after subarachnoid hemorrhage

1992 ◽  
Vol 76 (4) ◽  
pp. 635-639 ◽  
Author(s):  
Shigeru Nishizawa ◽  
Nobukazu Nezu ◽  
Kenichi Uemura
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Direct Evidence ◽  
Control Group ◽  
Content Type ◽  
Kinase C ◽  
Protein Kinase C Activity ◽  
Fine Print

✓ Vascular contraction is induced by the activation of intracellular contractile proteins mediated through signal transduction from the outside to the inside of cells. Protein kinase C plays a crucial role in this signal transduction. It is hypothesized that protein kinase C plays a causative part in the development of vasospasm after subarachnoid hemorrhage (SAH). To verify this directly, the authors measured protein kinase C activity in canine basilar arteries in an SAH model with (γ-32P)adenosine triphosphate and the data were compared to those in a control group. Protein kinase C is translocated to the membrane from the cytosol when it is activated, and the translocation is an index of the activation; thus, protein kinase C activity was measured both in the cytosol and in the membrane fractions. Protein kinase C activity in the membrane in the SAH model was remarkably enhanced compared to that in the control group. The percentage of membrane activity to the total was also significantly greater in the SAH vessels than in the control group, and the percentage of cytosol activity in the SAH group was decreased compared to that in the control arteries. The results indicate that protein kinase C in the vascular smooth muscle was translocated to the membrane from the cytosol and was activated when SAH occurred. It is concluded that this is direct evidence for a key role of protein kinase C in the development of vasospasm.

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