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- Sadegh, Mardjaneh Karbalaei, et al.
(författare)
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Biomechanical properties and innervation of the female caveolin-1-deficient detrusor.
- 2011
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Ingår i: British Journal of Pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; Dec, s. 1156-1170
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Caveolin-1-deficiency is associated with substantial urogenital alterations. Here, a mechanical, histological and biochemical characterization of female detrusors from wild-type (WT) and caveolin-1-deficient (KO) mice was made to increase the understanding of detrusor changes caused by lack of caveolae. Experimental approach: Length-tension relationships were generated, and we recorded responses to electrical field stimulation (EFS), the muscarinic receptor agonist carbachol, and the purinoceptor agonist ATP. Tyrosine nitration and the contents of caveolin-1, cavin-1, muscarinic M(3) receptors, phospholipase C(β1) (PLC(β1) ), muscle-specific kinase (MuSK), and L-type Ca(2+) -channels were determined by immunoblotting. Innervation was assessed by immunohistochemistry. Key results: Bladder to body weight ratio was not changed, nor was there any change in the optimum circumference for force development. Depolarization- and ATP-induced stress was reduced, as was carbachol-induced stress between 0.1 and 3 µM, but the supramaximal relative (% K(+) ) response to carbachol was increased, as was M(3) expression. The scopolamine-sensitive component of the EFS-response was impaired, and yet bladder nerves contained little caveolin-1. The density of cholinergic nerves was unchanged, whereas CART- and CGRP-positive nerves were reduced. Immunoblotting revealed loss of MuSK. Conclusions and implications: Ablation of caveolae in the female detrusor leads to generalised impairment of contractility, ruling out prostate hypertrophy as a contributing factor. Cholinergic neuroeffector transmission is impaired without conspicuous changes in the density of cholinergic nerves or morphology of their terminals, but correlating with reduced expression of MuSK.
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| 2. |
- Shakirova, Yulia, et al.
(författare)
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Human urinary bladder smooth muscle is dependent on membrane cholesterol for cholinergic activation.
- 2010
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 634, s. 142-148
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Tidskriftsartikel (refereegranskat)abstract
- Voiding is mediated by muscarinic receptors in urinary bladder smooth muscle cells. Lipid rafts and caveolae are cholesterol enriched membrane domains that modulate the activity of G protein-coupled receptors and second messenger systems. Conflicting findings regarding sensitivity of muscarinic signalling to cholesterol desorption, which perturbs lipid rafts and caveolae, have been reported, and no study has used human urinary bladder. Here, the dependence of human bladder muscarinic receptor signalling on plasma membrane cholesterol was examined. Nerve-mediated contraction, elicited by electrical field stimulation of human bladder strips, was impaired by desorption of cholesterol using methyl-beta-cyclodextrin, and the concentration-response curve for the muscarinic agonist carbachol was right-shifted. No effect of cholesterol desorption was observed in rat, and in mouse increased maximum contraction was seen. Expression of caveolin-1, PLC(beta1) and M(3) muscarinic receptors did not differ between species in a manner that would explain the differential sensitivity to cholesterol desorption. In human bladder, threshold depolarisation eliminated the difference between cyclodextrin-treated and control preparations. Contraction elicited by depolarisation per se was not affected. M(3) muscarinic receptors appeared clustered along plasma membrane profiles as shown by immunohistochemical staining of human bladder, but no redistribution in association with cholesterol reduction were seen. Thus, muscarinic receptor-induced contraction of the urinary bladder exhibits species-specific differences in its sensitivity to cholesterol desorption suggesting differential roles of lipid rafts/caveolae in muscarinic receptor signalling between species.
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