| 1. |
- Arlock, Per, et al.
(author)
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Excitation and contraction of cardiac muscle and coronary arteries of brain-dead pigs
- 2023
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In: FASEB BioAdvances. - : Wiley. - 2573-9832. ; 5:2, s. 71-84
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Journal article (peer-reviewed)abstract
- Excitability and contraction of cardiac muscle from brain-dead donors critically influence the success of heart transplantation. Membrane physiology, Ca2+-handling, and force production of cardiac muscle and the contractile properties of coronary arteries were studied in hearts of brain-dead pigs. Cardiac muscle and vascular function after 12 h brain death (decapitation between C2 and C3) were compared with properties of fresh tissue. In both isolated cardiomyocytes (whole-cell patch clamp) and trabecular muscle (conventional microelectrodes), action potential duration was shorter in brain dead, compared to controls. Cellular shortening and Ca2+ transients were attenuated in the brain dead, and linked to lower mRNA expression of L-type calcium channels and a slightly lower ICa,L, current, as well as to a lower expression of phospholamban. The current–voltage relationship and the current above the equilibrium potential of the inward K+ (IK1) channel were altered in the brain-dead group, associated with lower mRNA expression of the Kir2.2 channel. Delayed K+ currents were detected (IKr, IKs) and were not different between groups. The transient outward K+ current (Ito) was not observed in the pig heart. Coronary arteries exhibited increased contractility and sensitivity to the thromboxane analogue (U46619), and unaltered endothelial relaxation. In conclusion, brain death involves changes in cardiac cellular excitation which might lower contractility after transplantation. Changes in the inward rectifier K+ channel can be associated with an increased risk for arrhythmia. Increased reactivity of coronary arteries may lead to increased risk of vascular spasm, although endothelial relaxant function was well preserved.
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| 2. |
- Lövdahl, Cecilia
(author)
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Injury-induced activation of vascular smooth muscle cells. Role of specific gene expression and intracellular signalling pathways
- 2000
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Doctoral thesis (other academic/artistic)abstract
- Migration and proliferation of smooth muscle cells (SMC) are important events in the development of atherosclerosis and restenosis following angioplastic surgery. It is important to gain further knowledge about the mechanisms regulating SMC form and function in order to understand the underlying disease process. In this thesis I have used cultured rat aortic SMC and analysed how these cells respond to either a mechanical or enzymatic injury. The objective has been to identify the molecular mechanisms involved in injury-induced activation of SMC. I have focused my studies on the role of molecules regulating migration and proliferation. These include metalloproteinases and the intracellular signalling molecule ERK1/2. Increased expression of the migration-related stromelysin gene as well as early and transient expression of the transcription factor Ets-1 were detected when primary SMC were established in culture. Up-regulated Ets-1 expression was also seen in the rat carotid artery following balloon-injury. Since Ets-1 regulates the stromelysin gene, the role of stromelysin in injury-induced SMC activation was further investigated using antisense oligonucleotides directed towards the stromelysin translation initiation site. Treatment with antisense oligos inhibited phenotypic change as well as decreased the migration and proliferation of SMC after injury in vitro. Furthermore, these antisense oligos reduced neointimal thickening after balloon-injury in rat carotid arteries. Injury-induced ERK1/2 phosphorylation could be coupled to altered SMC function by the use of the MEK1-inhibitor PD98059. In addition, the synthetic metalloproteinase inhibitor Batimastat (BB94) reduced ERK1/2 activation as well as SMC migration and proliferation. Further studies demonstrated that Ca2+, calmodulin, tyrosine kinases, G-proteins and Src all appear to be involved in injury-induced ERK1/2 activation, migration and proliferation in SMC. In conclusion, these results suggest (1) a role for Ets-1 and metalloproteinases such as stromelysin in the SMC response to injury, (2) that the ERK1/2 is a key signalling molecule in the alteration of SMC function, (3) that release of Ca2+ is necessary for optimal ERK1/2 activation, and (4) that SMC activation due to injury is a result of signal transmission via several converging ERK1/2 connected pathways.
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| 3. |
- Moses, Sara, et al.
(author)
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Smooth muscle cell response to mechanical injury involves intracellular calcium release and ERK1/ERK2 phosphorylation
- 2001
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In: Experimental Cell Research. - : Elsevier BV. - 1090-2422 .- 0014-4827. ; 269:1, s. 88-96
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Journal article (peer-reviewed)abstract
- We have investigated possible signaling pathways coupled to injury-induced ERK1/2 activation and the subsequent initiation of vascular rat smooth muscle cell migration and proliferation. Aortic smooth muscle cells were cultured to confluency and subjected to in vitro injury under serum-free conditions. In fluo-4-loaded cells, injury induced a rapid wave of intracellular Ca(2+) release that propagated about 200 microm in radius from the injured zone, reached a peak in about 20 s, and subsided to the baseline within 2 min. The wave was abolished by prior treatment with the sarcoplasmic reticulum ATPase inhibitor thapsigargin, but not by omission of extracellular Ca(2+). ERK1/2 activation reached a peak at 10 min after injury and was inhibited by the MEK1 inhibitor PD98059, as well as by thapsigargin, fluphenazine, genistein, and the Src inhibitor PP2. These inhibitors also reduced [(3)H]thymidine incorporation and migration of cells into the injured area determined at 48 h after injury. These results show that mechanical injury to vascular smooth muscle cells induces a Ca(2+) wave which is dependent on intracellular Ca(2+) release. Furthermore, the injury activates ERK1/2 phosphorylation as well as cell migration and replication.
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| 4. |
- Olofsson, Peder S., et al.
(author)
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Blood pressure regulation by CD4+ lymphocytes expressing choline acetyltransferase
- 2016
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In: Nature Biotechnology. - : Nature Publishing Group. - 1087-0156 .- 1546-1696. ; 34:10, s. 1066-1071
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Journal article (peer-reviewed)abstract
- Blood pressure regulation is known to be maintained by a neuro-endocrine circuit, but whether immune cells contribute to blood pressure homeostasis has not been determined. We previously showed that CD4(+) T lymphocytes that express choline acetyltransferase (ChAT), which catalyzes the synthesis of the vasorelaxant acetylcholine, relay neural signals(1). Here we show that these CD4(+)CD44(hi)CD62L(Io) T helper cells by gene expression are a distinct T-cell population defined by ChAT (CD4 T-ChAT). Mice lacking ChAT expression in CD4(+) cells have elevated arterial blood pressure, compared to littermate controls. Jurkat T cells overexpressing ChAT (JT(ChAT)) decreased blood pressure when infused into mice. Co-incubation of JT(ChAT) and endothelial cells increased endothelial cell levels of phosphorylated endothelial nitric oxide synthase, and of nitrates and nitrites in conditioned media, indicating increased release of the potent vasorelaxant nitric oxide. The isolation and characterization of CD4 T-ChAT cells will enable analysis of the role of these cells in hypotension and hypertension, and may suggest novel therapeutic strategies by targeting cell-mediated vasorelaxation.
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