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| 2. |
- Hansen-Schwartz, Jacob, et al.
(författare)
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Endothelium-Dependent Relaxant Responses to Selective 5-HT(1B/1D) Receptor Agonists in the Isolated Middle Cerebral Artery of the Rat.
- 2003
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Ingår i: Journal of Vascular Research. - : S. Karger AG. - 1423-0135 .- 1018-1172. ; 40:6, s. 561-566
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Tidskriftsartikel (refereegranskat)abstract
- The vasomotor effects of triptans in the middle cerebral artery (MCA) of rats were studied using the pressurised arteriography method and in vitro vessel baths. Using the arteriograph, MCAs from Sprague-Dawley rats were mounted on two glass micropipettes, pressurised to 85 mm Hg and luminally perfused. Luminally added 5- hydroxytryptamine (5-HT), sumatriptan and rizatriptan induced maximal dilatations of 22 ± 4, 10 ± 2 and 13 ± 5%, respectively, compared to the resting diameter. The relaxant effect of sumatriptan was blocked by the 5- HT<sub>1B/1D</sub> receptor selective antagonist GR 55562 (10<sup>–6</sup><i>M</i>). The use of N<sup>ω</sup>-nitro-<i>L</i>-arginine and charybdotoxin revealed that the dilatation involved both nitric oxide and endothelially derived hyperpolarising factor. Thus, the earlier demonstrated expression of 5-HT<sub>1B/1D</sub> immunoreactivity in the endothelium may well translate into a relaxant response to 5-HT and triptans. Using the vessel bath technique, MCA segments were mounted on two metal wires. The relaxant responses to sumatriptan could not be reproduced using this model; instead, weak contractile responses (6 ± 3% of submaximal contractile capacity) were observed. The difference in observations between the experimental models may be related to the maintenance of shear stress in the arteriograph.
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- Ansar, Saema, et al.
(författare)
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ERK1/2 inhibition attenuates cerebral blood flow reduction and abolishes ET(B) and 5-HT(1B) receptor upregulation after subarachnoid hemorrhage in rat.
- 2006
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016 .- 0271-678X. ; 26:Nov 2, s. 846-856
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Tidskriftsartikel (refereegranskat)abstract
- Upregulation of endothelin B (ETB) and 5-hydroxytryptamine 1B (5-HT1B) receptors via transcription has been found after experimental subarachnoid hemorrhage (SAH), and this is associated with enhanced phosphorylation of the mitogen-activated protein kinase ( MAPK) extracellular signal-regulated kinase ( ERK1/2). In the present study, we hypothesized that inhibition of ERK1/2 alters the ETB and 5-HT1B receptor upregulation and at the same time prevents the sustained cerebral blood flow (CBF) reduction associated with SAH. The ERK1/2 inhibitor SB386023-b was injected intracisternally in conjunction with and after the induced SAH in rats. At 2 days after the SAH, cerebral arteries were harvested for quantitative real-time polymerase chain reaction, immunohistochemistry and analysis of contractile responses to endothelin-1 (ET-1; ETA and ETB receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1 receptor agonist) in a sensitive myograph. To investigate if ERK1/2 inhibition had an influence on the local and global CBF after SAH, an autoradiographic technique was used. At 48 h after induced SAH, global and regional CBF were reduced by 50%. This reduction was prevented by treatment with SB386023-b. The ERK1/2 inhibition also decreased the maximum contraction elicited by application of ET-1 and 5-CT in cerebral arteries compared with SAH. In parallel, ERK1/2 inhibition downregulated ETB and 5-HT1B receptor messenger ribonucleic acid and protein levels compared with the SAH. Cerebral ischemia after SAH involves vasoconstriction and subsequent reduction in the CBF. The results suggest that ERK1/2 inhibition might be a potential treatment for the prevention of cerebral vasospasm and ischemia associated with SAH.
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| 4. |
- Ansar, Saema, et al.
(författare)
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Protein kinase C inhibition prevents upregulation of vascular ET(B) and 5-HT(1B) receptors and reverses cerebral blood flow reduction after subarachnoid haemorrhage in rats.
- 2007
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016 .- 0271-678X. ; 27:1, s. 21-32
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenesis of cerebral ischaemia after subarachnoid haemorrhage (SAH) still remains elusive. The purpose of the present study was to examine whether specific protein kinas C (PKC) inhibition in rats could alter the transcriptional SAH induced Endothelin (ET) type B and 5-hydroxytryptamine type 1B (5-HT1B) receptor upregulation and prevent the associated cerebral blood flow (CBF) reduction. The PKC inhibitor RO-31-7549 or vehicle was injected intracisternally after the induced SAH in rats (n = 3 to 10 in each groups for each method). The involvement of the PKC isoforms was investigated with Western blot; only PKC delta and PKC alpha subtypes were increased after SAH RO-31-7549 treatment abolished this. At 2 days after the SAH basilar and middle cerebral arteries were harvested and the contractile response to endothelin-1 (ET-1; ETA and ETB receptor agonist) and 5-carboxamidotryptamine (5-CT; 5-HT1B receptor agonist) were investigated with a myograph. The contractile responses to ET-1 and 5-CT were increased (P < 0.05) after SAH compared with sham operated rats. In parallel, the ETB and 5-HT1B receptor mRNA and protein expression were significantly elevated after SAH, as analysed by quantitative real-time polymerase chain reaction and immunohistochemistry, respectively. Administration of RO-31-7549 prevented the upregulated contraction elicited by application of ET-1 and 5-CT in cerebral arteries and kept the ETB and 5-HT1B receptor mRNA and protein levels at pre-SAH levels. Regional and global CBF evaluated by an autoradiographic technique were reduced by 60% 64% after SAH (P < 0.05) and prevented by treatment with RO-31-7549. Our study suggests that PKC plays an important role in the pathogenesis of cerebral ischaemia after SAH.
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| 5. |
- Hansen-Schwartz, Jacob, et al.
(författare)
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Cerebral vasoconstriction after subarachnoid hemorrhage - Role of changes in vascular receptor phenotype
- 2008
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Ingår i: Frontiers in Bioscience. - : IMR Press. - 1093-9946 .- 1093-4715. ; 13, s. 2160-2164
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Tidskriftsartikel (refereegranskat)abstract
- The pathological constriction of cerebral arteries known as cerebral vasospasm (CVS) is with a delay of 4 to 10 days linked to subarachnoid hemorrhage. Several agents have been suggested as being responsible; amongst these perhaps 5-hydroxytryptamine (5-HT) and endothelin-1 (ET-1) are the most prominent given their ability to elicit powerful constriction of cerebral arteries. Investigating both 5-HT and ET receptors we have observed that there are distinct changes in receptor phenotype after experimental SAH, namely upregulation of the ETB and 5-HT1B receptors, and that this upregulation is linked to a higher sensitivity to the endogenous agonists. It has also been shown that reduction in regional cerebral blood flow (CBF) is associated with receptor upregulation and interventional animal experiments have shown a benefit from inhibiting the PKC and MAP kinase pathways on receptor upregulation, CBF and neurological outcome.
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| 6. |
- Hansen-Schwartz, Jacob, et al.
(författare)
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Human endothelin subtype a receptor enhancement during tissue culture via de novo transcription
- 2002
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Ingår i: Neurosurgery. - 0148-396X. ; 50:1, s. 127-133
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Endothelin (ET) has, since its discovery, increasingly been considered a key player in the pathophysiological processes of cerebral vasospasm in the course of subarachnoid hemorrhage, although it remains unclear how ET is involved. We present data that indicate an inherent capacity of human cerebral arteries to change their sensitivity to ET. METHODS: Human cerebral arteries were obtained from patients undergoing intracranial tumor surgery. The vessels were divided into segments and subjected to organ culture for 48 hours. The vessels were then examined by using in vitro pharmacological methods and molecular biological techniques. RESULTS: After organ culture of the cerebral arteries, both the sensitivity to and potency of ET were enhanced (maximal response, 152 +/- 9%; -log (50% effective concentration), 10.3 +/- 0.3), in comparison with data for fresh cerebral arteries. Contractions were inhibited by both FR139317 (a specific ETA receptor antagonist) and bosentan (a mixed ETA and ETB receptor antagonist), in a manner indicating the sole presence of contractile ETA receptors. An inconsistent dilative response to the selective ETB receptor agonist sarafotoxin 6c was observed; the response was preserved in some segments and abolished in others, and potentiation of the precontraction was observed in yet other segments. No isolated contractile response to sarafotoxin 6c was observed, however. In reverse transcription-polymerase chain reaction assays, both ETA and ETB receptor messenger ribonucleic acid was detected. CONCLUSION: These results demonstrate that human cerebral arteries are capable of enhancing the function of ETA receptors.
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| 7. |
- Hansen-Schwartz, Jacob
(författare)
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On receptor changes in cerebral arteries after subarachnoid haemorrhage
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Overall the aim has been to characterise the in vitro upregulation of the 5-hydroxytryptamine 1B/1D (5-HT(1B/1D)) and endothelin (ET) receptors in the cerebral circulation as well as demonstrating phenotypic changes in a pathophysiological model mimicking subarachnoid haemorrhage. The first part describes receptor upregulation using organ culture of whole vessel segments from both rat and man. The upregulation is dependent on gene transcription and translation; thus, an active signalling pathway is involved. Further analysis of this pathway revealed that protein kinase C is especially important in the upregulation process of the ET(B) receptor. The second part attempts to take the concept of receptor upregulation into the pathophysiological realm, especially focusing on experimental subarachnoid haemorrhage. Changes similar to those observed using the in vitro organ culture technique were observed in vivo. Especially the ET(B) receptor upregulates and perhaps more importantly, this appears to be associated with a generally increased sensitivity towards ET-1. Now, even at physiological concentrations of ET-1 were appreciable contraction observed. Similar results were obtained when studying the upregulation of the 5-HT(1B) receptor; the upregulation imparts increased sensitivity of the cerebral arteries towards serotonin. The increased functional responses represent a significant contribution towards the understanding of cerebral vasospasm after subarachnoid haemorrhage. Finally, it is revealed that the ET(B) receptor is more frequently present in human arteries from patients with cerebrovascular disease thus substantiating the idea of receptor upregulation as part of human cerebrovascular pathology.
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| 8. |
- Hansen-Schwartz, Jacob, et al.
(författare)
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Protein kinase mediated upregulation of endothelin A, endothelin B and 5-hydroxytryptamine 1B/1D receptors during organ culture in rat basilar artery.
- 2002
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 137:1, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- 1 Organ culture has been shown to upregulate both endothelin (ET) and 5-hydroxytryptamine 1B/1D (5-HT(1B/1D)) receptors in rat cerebral arteries. The purpose of the present study was to investigate the involvement of protein kinases, especially protein kinases C (PKC) and A (PKA) in this process. 2 The effect of inhibiting protein kinases during organ culture with staurosporine (unspecific protein kinase inhitor), RO 31-7549 (specific inhibitor of classical PKC's) and H 89 (specific inhibitor of PKA) was examined using in vitro pharmacological examination of cultured vessel segments with ET-1 (unspecific ET(A) and ET(B) agonist), S6c (specific ET(B) agonist) and 5-CT (5-HT(1) agonist). Levels of mRNA coding for the ET(A), ET(B), 5-HT(1B) and 5-HT(1D) receptors were analysed using real-time RT-PCR. 3 Classical PKC's are critically involved in the appearance of the ET(B) receptor; co-culture with RO 31-7549 abolished the contractile response (6.9+/-1.8%) and reduced the ET(B) receptor mRNA by 44+/-4% as compared to the cultured control. Correlation between decreased ET(B) receptor mRNA and abolished contractile function indicates upstream involvement of PKC. 4 Inhibition of PKA generally had an enhancing effect on the induced changes giving rise to a 7-25% increase in E(max) in response to ET-1, S6c and 5-CT as compared to the cultured control. 5 Staurosporine inhibited the culture induced upregulation of the response of both the ET(A) and the 5-HT(1B/1D) receptors, but had no significant effect on the mRNA levels of these receptors. This lack of correlation indicates an additional downstream involvement of protein kinases. British Journal of Pharmacology (2002) 137, 118-126. doi:10.1038/sj.bjp.0704838
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