Calcium calmodulin-dependent protein kinase signal transduction in cerebral arteries

Cerebral arteries participate actively in the response that follows an episode of cerebral ischemia in man and rat. It has been shown that the vascular endothelin receptor expression is increased in stroke and organ culture. Furthermore, studies have demonstrated the intracellular signalling pathways, leading to the enhanced expression of vascular endothelin receptors. We have revealed that both calcium calmodulin dependent protein kinase and mitogen activated protein kianses play an important role. The signal transduction processes lead to powerful and prolonged effects of the initial activation. The synergistic nature of these processes, involve several gene groups. Our hypothesis is that inhibition of CAMK signal transduction would have effects on genes that are involved in cerebral ischemia and cerebrovascular receptor upregulation. The results of these studies show that the effect of CAMK or ERK1/2 inhibitor was stronger and more effective compared to that of other MAPK kinases. On the other hand the ability of CAMK to attenuate the contractions induced not only by endothelin receptors but also potassium depolarization revealed the unique role of CAMK in contraction of cerebral arteries. Investigation of the CAMK intracellular pathways shows the dependence of the intra-cellular calcium channel IP3R and CAMK on endothelin receptor expression. Further in vivo studies using the SAH model in rat showed that a CAMK inhibitor attenuated contractions induced by ET-1. It suggests an important role of the CAMK in late vasospasm after SAH. This thesis provides new perspectives on the pathophysiology of cerebral ischemia, and provides a possible explanation to the beneficial effects of treatment with CAMK inhibitors to limit the sequels of cerebral ischemia

Involvement of calcium-calmodulin-dependent protein kinase II in endothelin receptor expression in rat cerebral arteries

Waldsee R, Ahnstedt H, Eftekhari S, Edvinsson L. Involvement of calcium-calmodulin-dependent protein kinase II in endothelin receptor expression in rat cerebral arteries. Am J Physiol Heart Circ Physiol 298: H823-H832, 2010. First published December 11, 2009; doi:10.1152/ajpheart.00759.2009.-Experimental cerebral ischemia and organ culture of cerebral arteries result in the enhanced expression of endothelin ETB receptors in smooth muscle cells via increased transcription. The present study was designed to evaluate the involvement of calcium-calmodulin-dependent protein kinase (CAMK) in the transcriptional expression of endothelin receptors after organ culture. Rat basilar arteries were incubated for 24 h with or without the CAMK inhibitor KN93 or ERK1/2 inhibitor U0126. The contractile responses to endothelin-1 (ET-1; ETA and ETB receptor agonist) and sarafotoxin 6c (S6c; ETB receptor agonist) were studied using a sensitive myograph. The mRNA levels of the ETA and ETB receptors and CAMKII were determined by real-time PCR, and their protein levels were evaluated by immunohistochemistry and Western blot. The mRNA levels of CAMKII and the ETB receptor increased during organ culture, but there was no change in the expression of the ETA receptor. This effect was abolished by coincubation with KN93 or U0126. In functional studies, both inhibitors attenuated the S6c-induced contraction. Incubating the arteries with KN93, but not U0126, decreased the amount of phosphorylated CAMKII. The inhibitors had no effect on the levels of myosin light chain during organ culture, as measured by Western blot. CAMKII is involved in the upregulation of the endothelin ETB receptor and interacts with the ERK1/2 pathway to enhance receptor expression. CAMKII has no effect on the contractile apparatus in rat cerebral arteries

CaMKII inhibition with KN93 attenuates endothelin and serotonin receptor-mediated vasoconstriction and prevents subarachnoid hemorrhage-induced deficits in sensorimotor function

It has been suggested that transcriptional upregulation of cerebral artery contractile endothelin (ETB) and 5-hydroxytryptamine (5-HT1B) receptors play an important role in the development of late cerebral ischemia and increased vasoconstriction after subarachnoid hemorrhage (SAH). We tested the hypothesis that inhibition of calcium calmodulin-dependent protein kinase II (CaMKII) may reduce cerebral vasoconstriction mediated by endothelin and serotonin receptors and improve neurological outcome after experimental SAH

CaMKII and MEK1/2 inhibition time-dependently modify inflammatory signaling in rat cerebral arteries during organ culture.

Cerebral ischemia induces transcriptional upregulation of inflammatory genes in the brain parenchyma and in cerebral arteries, thereby contributing to the infarct development. The present study was designed to evaluate the involvement of calcium-calmodulin-dependent protein kinase (CaMKII) II and extracellular signal-regulated kinase1/2 (ERK1/2) on inflammatory mediators in rat cerebral arteries using organ culture as a method for inducing ischemic-like vascular wall changes

Cooperative effect of angiotensin AT, and endothelin ETA receptor antagonism limits the brain damage after ischemic stroke in rat

Cerebral ischemia results in enhanced expression of smooth muscle cell endothelin and angiotensin receptors in cerebral arteries. We hypothesise that this phenomenon may be detrimental and that acute treatment with a combined non-hypotensive dose of the angiotensin AT, receptor inhibitor candesartan and the endothelin ETA receptor antagonist ZD 1611 reduces the infarct in experimental ischemic stroke. Transient middle cerebral artery occlusion was induced in male Wistar rats by the intraluminal filament technique for 2 h followed by recirculation. The animals received systemic candesartan (0.05 mg/kg/day), ZD1611 (0.15 mg/kg/day), both combined or vehicle with start immediately after the occlusion. After 48 h the rats were sacrificed, the brains sliced and stained with 1% 2, 3, 5-triphenyltetrazolium chloride (TTC) and the volume of ischemic damage determined. The middle cerebral arteries were harvested for immunocytochemical studies of angiotensin AT, and endothelin ETA receptor expression. Candesartan or ZD1611 did alone not significantly decrease the brain damage or improve neurological scores as compared to vehicle controls. The combined inhibition of angiotensin AT, and endothelin ETA receptors however decreased the brain damage and improved the neurological scores (both P < 0.05). The treatment did not change resting mean arterial blood pressure. In addition, there was an upregulation of angiotensin AT, receptors in the ischemic middle cerebral artery smooth muscle cells, which was normalised by the combined treatment. In conclusion, the present study shows that combined inhibition of angiotensin AT, and endothelin ETA receptors reduces the brain damage and improves the neurological outcome after ischemic stroke in rat. (c) 2007 Elsevier B.V. All rights reserved