female arteries. In addition, we 22277057 tested the selective ETB receptor agonist sarafotoxin S6c, which did not induce any vasoconstrictor responses, in agreement with earlier observations in fresh and cultured human cerebral arteries. Age The pEC50 values for 5-CT and Ang II, and the EMAX for ET-1 were plotted against age of the patient to examine possible correlations between age and vasomotor reactivity. Linear regression analyses showed that the slopes were not significantly different from zero, except for Ang II. 16580199 The linear regression for Ang II in female cerebral arteries had a slope of -0.0460.01 indicating a minor decrease in pEC50 with increasing age. Real-time PCR The effect of organ culture on 5-HT1B, AT1 and ETB receptor 
mRNA levels was evaluated by real-time PCR of arterial segments taken before and after culture. 5-HT1B receptor mRNA was significantly increased in females after organ culture while the set statistical level of significance was not reached in males. However, previous data have shown this in diseased stroke patients. AT1 receptor mRNA levels were markedly increased in both male and female cerebral arteries. Incubation of cerebral arteries for 48 h increased ETB receptor mRNA GS 4059 expression in females. Values are represented as mean 6 SEM, with n representing the number of patients. Statistical analyses were performed using the non-parametric Mann-Whitney’s test. a P = 0.09, b P = 0.08 compared to females. Response too low to accurately calculate pEC50. 5-CT 5-carboxamidotryptamine, Ang II angiotensin II, ET-1 endothelin-1. clusive result could be obtained regarding ET-1 expression in fresh and incubated arteries in these patients. Localization of G-protein coupled receptors and angiotensin II in endothelial cells. Immunoreactivity to 5- Immunohistochemistry Htx-eosin staining was performed on all specimens. No morphological differences were observed between non-incubated and incubated arteries or between male and female arteries, which is in agreement with earlier data. Upregulation of G-protein coupled receptors and angiotensin II in vascular smooth muscle. Protein expres- sion of 5-HT1B, AT1 and ETB receptors and Ang II were examined by indirect immunohistochemistry of both fresh arteries and arteries incubated for 48 h. 5-HT1B, AT1 and ETB receptor immunoreactivity was markedly increased in VSMCs of incubated male and female arteries compared to fresh arteries. Interestingly, female and male arteries showed increase of receptor immunoreactivity after organ culture and no obvious sex differences in receptor immunoreactivity was detected. This was surprising in light of the differences in contractility that were observed. The expression of Ang II was also examined. An increase in immunoreactivity was observed in the medial layer of both male and female arteries after 48 h of organ culture. In addition, fluorescence intensity measurements in the smooth muscle cell layer showed increased immunoreactivity in both male and female cerebral arteries after organ culture. ET-1 immunoreactivity in arteries from male and female patients showed high inter-individual differences. Consequently, no con- HT1B and ETB receptors and Ang II was found not only in the smooth muscle, but also in endothelial cells. This endothelial localization was observed in both male and female arteries, and in fresh and incubated arteries. However, endothelial immunoreactivity could not be found in all patients, most likely due to loss of endothelial c