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Maximum Contraction (maximum + contraction)
Selected AbstractsExpression of RhoA mRNA and activated RhoA in urothelium and smooth muscle, and effects of a rho-kinase inhibitor on contraction of the porcine urinary bladder,,NEUROUROLOGY AND URODYNAMICS, Issue 6 2009Kimihiro Nakanishi Abstract Aims To investigate the concentration and activity of RhoA in detrusor and urothelium, as well as the effects of a Rho-kinase inhibitor, Y-27632 {(+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl) cyclohexanecarboxamide dihydrochloride}, on contraction of the pig urinary bladder. Methods The concentration of RhoA mRNA was studied by the real-time RT-PCR and activated RhoA enzyme was studied by activation assay and Western blotting. In functional studies, the response to Y-27632 was examined in bladder strips with or without urothelium. Results The concentration of RhoA mRNA (n,=,38) and activated RhoA enzyme (n,=,19) were greater in urothelium than in detrusor. Tension decrease after administration of Y-27632 (1 nM to 100 µM) was significantly greater in tissues with urothelium than in tissues without urothelium, after pre-contraction with KCl (decrease by 52.0,±,4.6% vs. 28.0,±,6.8%, respectively; P,=,0.0088) or with carbachol (decrease by 53.1,±,7.2% vs. 30.6,±,5.8%, respectively; P,=,0.0035). Maximum contraction on CRC to carbachol was reduced significantly after administration of 3, 10, and 30 µM Y-27632 (to 72.2,±,6.8%, 43.9,±,7.1%, and 25.0,±,5.5%, respectively, of the control value) in strips with intact urothelium (n,=,36), but was reduced only at 10 and 30 µM (to 66.7,±,8.3% and 85.6,±,2.6%, respectively) in tissues without urothelium (n,=,20). Inhibitory effect of Y-27632 (3,30 µM) on the response to electrical field stimulation at 20 and 50 Hz was also greater in tissues with intact urothelium than in tissues without urothelium. Conclusions The concentration of RhoA mRNA and activated RhoA enzyme were greater in urothelium than in detrusor. Y-27632 showed a stronger inhibitory effect in detrusor with intact urothelium than in dose without urothelium. Neurourol. Urodyn. 28:521,528, 2009. © 2009 Wiley-Liss, Inc. [source] Relaxant effects of , -adrenergic agonists on porcine and human detrusor muscleACTA PHYSIOLOGICA, Issue 2 2005J. K. Badawi Abstract Aim:, Relaxant effects of different , -adrenoceptor agonists on porcine and human detrusor were examined. Thus, the , -adrenoceptor subtype mainly responsible for relaxation in the detrusor muscle of pigs was characterized. Additionally, different effects of several , -agonists in both species were shown. Methods:, Experiments were performed on muscle strips of porcine and human detrusor suspended in a tissue bath. The relaxant effects of the non-selective , -agonist isoprenaline, the selective ,2-agonists procaterol, salbutamol and the selective ,3-agonists BRL 37344, CL 316 243 and CGP 12177 on potassium-induced contraction were investigated. The inhibitory effect of different substances on the maximum contraction and the rank order of potency for endogenous catecholamines was determined in pigs. Furthermore, concentration-relaxation curves were performed for pigs and humans. Results:,Pigs: In the pre-treatment experiments isoprenaline and procaterol showed similar effects. The concentration,response experiments showed that the maximum relaxation induced by procaterol and salbutamol was more than 90%, not significantly different from isoprenaline, whereas the maximum relaxations of CL 316 243, BRL 37344 and CGP 12177 amounted to 68, 70 or 30%, respectively. Rank order of potencies was isoprenaline , adrenaline > noradrenaline. Humans: Isoprenaline, procaterol, salbutamol and CL 316 243 showed a maximum relaxation of 80, 41, 24 and 35% and pD2 values of 6.24, 5.65, 5.48 and 5.55, respectively. Conclusion:,,2-receptors play a main functional role in mediating relaxation of porcine detrusor. Selective ,2- and ,3-agonists similarly relax the human detrusor. Effects were smaller compared with the pig. [source] Relation between spasticity and strength in individuals with spastic diplegic cerebral palsyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 3 2002Sandy A Ross MHS PT PCS The relation between spasticity and strength in individuals with cerebral palsy (CP) has not been extensively researched. Knee and ankle spasticity and strength were quantified in a retrospective analysis of 60 individuals with spastic diplegic CP (mean age 12 years, range 3 to 38) and a group of 50 individuals without disabilities (WD group; mean age 12 years, range 4 to 36). Spasticity was measured using a KinCom dynamometer that stretched the passive knee flexors or ankle plantarflexors at different speeds and recorded the amount of resistive torques. For the strength tests, the participant performed a maximum contraction of the knee flexors/extensors and ankle plantarflexors/dorsiflexors throughout their range of motion at a speed of 10/s on the dynamometer. Pearson's correlation coefficient was used to determine if a relation existed between spasticity and strength within the same muscle group and in opposing muscle groups at the knee and ankle joints. A t-test was performed to determine if greater spasticity and less strength existed at the ankles compared with the knees in those with CP. Results show that there was no relation between spasticity and strength either within the same muscle group or at opposing muscle groups at the knee and ankle joints in persons with CP. Individuals with spastic diplegic CP were more involved (greater spasticity, less strength) distally at the ankles compared with the knees. The findings conflict with the literature, which contains several assumptions, one of which is that a spastic muscle is a strong muscle and that spasticity causes weakness in the opposing muscle group. We found no relation between spasticity and strength in individuals with CP. Our findings support the literature, which states that individuals with spastic diplegic CP are more involved distally compared with proximally in the lower extremities. [source] Impact of delivery mode on electromyographic activity of pelvic floor: Comparative prospective study,NEUROUROLOGY AND URODYNAMICS, Issue 7 2010Simone Botelho Abstract Aims Several studies evidenced the association between pregnancy, mode of delivery and genitourinary symptoms. However, there are still controversies about the role of mode of delivery in the prevention or aggravation of these symptoms. This study aimed to compare the impact of three distinct modes of delivery on pelvic floor muscle contractility. Methods Seventy-five primiparous women were divided into three groups: (1) vaginal delivery with mediolateral episiotomy (n,=,28); (2) elective cesarean section (n,=,26); (3) emergency cesarean section (n,=,21). All patients underwent vaginal digital examination, grading the muscle contractility from 0 to 5 and surface electromyography (EMG) of the pelvic floor during the last trimester of pregnancy and 45 days after delivery. Results There was a significant increase in pelvic floor contractility in the elective cesarean section group, from 2.35 to 2.92 (P,=,0.03), when compared to the vaginal delivery and emergency cesarean section groups. Analysis of electromyography data showed a significant reduction in maximum contraction of the pelvic floor after vaginal delivery, from 39.17 to 31.14,µV (P,=,0.001), which was not observed in both cesarean section groups. Conclusion Vaginal delivery was associated with a decrease in pelvic floor muscle strength and endurance 45 days after delivery when compared to elective cesarean section as well as emergency cesarean section. Neurourol. Urodynam. 29:1258,1261, 2010. © 2010 Wiley-Liss, Inc. [source] Functional importance of the actin cytoskeleton in contraction of bovine iris sphincter muscleAUTONOMIC & AUTACOID PHARMACOLOGY, Issue 3 2002J. A. C. Filipe Summary 1 The contractile capacity of smooth muscle cells depends on the cytoskeletal framework of the cell. The aim of this study was to determine the functional importance of both the actin and the tubulin components of the cytoskeleton in contractile responses of the bovine isolated iris sphincter muscle. 2 In each preparation, two contractions to the muscarinic agonist carbachol were obtained. The maximum responses of the first contractions were taken as 100%. The second contractions to carbachol were elicited in the presence of either cytochalasin B (50 and 5 ,m), an inhibitor of the actin cytoskeleton, or colchicine (100 ,m), an inhibitor of the tubulin cytoskeleton (30 min incubation). 3 Cytochalasin B, at a concentration of 50 ,m, significantly decreased the contractions induced by carbachol, with the maximum response reduced to 21.8 ± 6.6% (n = 12) of the initial maximum. The maximal contractions to carbachol in the presence of colchicine reached 96.2 ± 7.9% (n = 9) of the initial contraction, which was not significantly different from control second responses to carbachol with neither drug present, which reached 113.3 ± 7.6% (n = 7). 4 The effect of cytochalasin B was dose-dependent, since at a lower concentration of 5 ,m, the drug decreased the maximum contraction to carbachol to 60.3 ± 8.8% (n = 6). The effect of cytochalasin B was at least partially reversible, since after the use of the higher concentration of 50 ,m, contractions to carbachol increased to 62.3 ± 15.5% (n = 4) of the maximal response, after 1 h repeated washing of the preparations. 5 Cytochalasin D, at a concentration of 50 ,m, completely abolished the contractions induced by carbachol (n = 4). 6 These findings suggest that in bovine iris sphincter muscle, contractions to carbachol are highly dependent, from a functional point of view, on actin polymerization, and not, to any important degree, on the polymerization of tubulin. [source] | ||||||||||