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Liu G, Obara K, Yoshioka K, Tanaka Y. Pharmacological Studies on the Ca 2+ Influx Pathways in Platelet-Activating Factor (PAF)-Induced Mouse Urinary Bladder Smooth Muscle Contraction. Biol Pharm Bull 2023; 46:997-1003. [PMID: 37394649 DOI: 10.1248/bpb.b22-00923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Platelet-activating factor (PAF) not only acts as a mediator of platelet aggregation, inflammation, and allergy responses but also as a constrictor of various smooth muscle (SM) tissues, including gastrointestinal, tracheal/bronchial, and pregnancy uterine SMs. Previously, we reported that PAF induces basal tension increase (BTI) and oscillatory contraction (OC) in mouse urinary bladder SM (UBSM). In this study, we examined the Ca2+ influx pathways involved in PAF-induced BTI and OC in the mouse UBSM. PAF (10-6 M) induced BTI and OC in mouse UBSM. However, the PAF-induced BTI and OC were completely suppressed by extracellular Ca2+ removal. PAF-induced BTI and OC frequencies were markedly suppressed by voltage-dependent Ca2+ channel (VDCC) inhibitors (verapamil (10-5 M), diltiazem (10-5 M), and nifedipine (10-7 M)). However, these VDCC inhibitors had a minor effect on the PAF-induced OC amplitude. The PAF-induced OC amplitude in the presence of verapamil (10-5 M) was strongly suppressed by SKF-96365 (3 × 10-5 M), an inhibitor of receptor-operated Ca2+ channel (ROCC) and store-operated Ca2+ channel (SOCC), but not by LOE-908 (3 × 10-5 M) (an inhibitor of ROCC). Overall, PAF-induced BTI and OC in mouse UBSM depend on Ca2+ influx and the main Ca2+ influx pathways in PAF-induced BTI and OC may be VDCC and SOCC. Of note, VDCC may be involved in PAF-induced BTI and OC frequency, and SOCC might be involved in PAF-induced OC amplitude.
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Affiliation(s)
- Ge Liu
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University
| | - Keisuke Obara
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University
| | - Kento Yoshioka
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University
| | - Yoshio Tanaka
- Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University
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Eshkoor SA, Hamid TA, Shahar S, Mun CY. Factors Related to Urinary Incontinence among the Malaysian Elderly. J Nutr Health Aging 2017; 21:220-226. [PMID: 28112780 DOI: 10.1007/s12603-016-0779-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Urinary incontinence is a prevalent condition in the elderly that is the spontaneous leakage of urine. It is an age-related problem and increases especially in people aged above 65 years. It can cause many psychological, behavioral, biological, economic and social effects. The treatment of urinary incontinence can reduce morbidity and mortality. Thus, this study aimed to determine the effects of variables including age, ethnicity, gender, education, marital status, body weight, blood elements and nutritional parameters on urinary incontinence among the Malaysian elderly. METHODS The study was on 2322 non-institutionalized Malaysian elderly. The hierarchy logistic regression analysis was applied to estimate the risk of independent variables for urinary incontinence among respondents. RESULTS The findings indicated that approximately 3.80% of subjects had urinary incontinence. In addition, constipation was found a significant factor that increased the risk of urinary incontinence in samples (p=0.006; OR=3.77). The increase in dietary monounsaturated fat (p=0.038; OR=0.59) and plasma triglyceride levels (p=0.029; OR=0.56) significantly reduced the risk of incontinence in subjects. Many of suspected variables including socio-demographic factors, diseases, nutritional minerals, blood components and body weight were non-relevant factors to urinary incontinence in respondents. CONCLUSIONS Constipation increased the risk of urinary incontinence in subjects, and increase in dietary monounsaturated fat and plasma triglyceride levels decreased the risk.
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Affiliation(s)
- S A Eshkoor
- Tengku Aizan Hamid, Malaysian Research on Aging (MyAging), University Putra Malaysia, Serdang, Malaysia, E-mail:
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Hashitani H, Lang RJ, Mitsui R, Mabuchi Y, Suzuki H. Distinct effects of CGRP on typical and atypical smooth muscle cells involved in generating spontaneous contractions in the mouse renal pelvis. Br J Pharmacol 2010; 158:2030-45. [PMID: 20050194 DOI: 10.1111/j.1476-5381.2009.00514.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE We investigated the cellular mechanisms underlying spontaneous contractions in the mouse renal pelvis, regulated by calcitonin gene-related peptide (CGRP). EXPERIMENTAL APPROACH Spontaneous contractions, action potentials and Ca2+ transients in typical and atypical smooth muscle cells (TSMCs and ATSMCs) within the renal pelvis wall were recorded separately using tension and intracellular microelectrode recording techniques and Fluo-4 Ca2+ imaging. Immunohistochemical and electron microscopic studies were also carried out. KEY RESULTS Bundles of CGRP containing transient receptor potential cation channel, subfamily V, member 1-positive sensory nerves were situated near both TSMCs and ATSMCs. Nerve stimulation reduced the frequency but augmented the amplitude and duration of spontaneous phasic contractions, action potentials and Ca2+ transients in TSMCs. CGRP and agents increasing internal cyclic adenosine monophosphate (cAMP) mimicked the nerve-mediated modulation of TSMC activity and suppressed ATSMCs Ca2+ transients. Membrane hyperpolarization induced by CGRP or cAMP stimulators was blocked by glibenclamide, while their negative chronotropic effects were less affected. Glibenclamide enhanced TSMC Ca2+ transients but inhibited ATSMC Ca2+ transients, while both 5-hydroxydecanoate and diazoxide, a blocker and opener of mitochondrial ATP-sensitive K+ channels, respectively, reduced the Ca2+ transient frequency in both TSMCs and ATSMCs. Inhibition of mitochondrial function blocked ATSMCs Ca2+ transients and inhibited spontaneous excitation of TSMCs. CONCLUSIONS AND IMPLICATIONS The negative chronotropic effects of CGRP result primarily from suppression of ATSMC Ca2+ transients rather than opening of plasmalemmal ATP-sensitive K+ channels in TSMCs. The positive inotropic effects of CGRP may derive from activation of TSMC L-type Ca2+ channels. Mitochondrial Ca2+ handling in ATSMCs also plays a critical role in generating Ca2+ transients.
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Affiliation(s)
- Hikaru Hashitani
- Department of Cell Physiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan.
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Abstract
The sarcoplasmic reticulum (SR) of smooth muscles presents many intriguing facets and questions concerning its roles, especially as these change with development, disease, and modulation of physiological activity. The SR's function was originally perceived to be synthetic and then that of a Ca store for the contractile proteins, acting as a Ca amplification mechanism as it does in striated muscles. Gradually, as investigators have struggled to find a convincing role for Ca-induced Ca release in many smooth muscles, a role in controlling excitability has emerged. This is the Ca spark/spontaneous transient outward current coupling mechanism which reduces excitability and limits contraction. Release of SR Ca occurs in response to inositol 1,4,5-trisphosphate, Ca, and nicotinic acid adenine dinucleotide phosphate, and depletion of SR Ca can initiate Ca entry, the mechanism of which is being investigated but seems to involve Stim and Orai as found in nonexcitable cells. The contribution of the elemental Ca signals from the SR, sparks and puffs, to global Ca signals, i.e., Ca waves and oscillations, is becoming clearer but is far from established. The dynamics of SR Ca release and uptake mechanisms are reviewed along with the control of luminal Ca. We review the growing list of the SR's functions that still includes Ca storage, contraction, and relaxation but has been expanded to encompass Ca homeostasis, generating local and global Ca signals, and contributing to cellular microdomains and signaling in other organelles, including mitochondria, lysosomes, and the nucleus. For an integrated approach, a review of aspects of the SR in health and disease and during development and aging are also included. While the sheer versatility of smooth muscle makes it foolish to have a "one model fits all" approach to this subject, we have tried to synthesize conclusions wherever possible.
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Affiliation(s)
- Susan Wray
- Department of Physiology, School of Biomedical Sciences, University of Liverpool, Liverpool, Merseyside L69 3BX, United Kingdom.
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Li S, Hydery T, Juan Y, Lin WY, Kogan B, Mannikarottu A, Leggett RE, Schuler C, Levin RM. The Effect of 2- and 4-Week Ovariectomy on Female Rabbit Urinary Bladder Function. Urology 2009; 74:691-6. [DOI: 10.1016/j.urology.2009.02.068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 02/02/2009] [Accepted: 02/04/2009] [Indexed: 10/20/2022]
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Exintaris B, Nguyen DTT, Lam M, Lang RJ. Inositol trisphosphate-dependent Ca stores and mitochondria modulate slow wave activity arising from the smooth muscle cells of the guinea pig prostate gland. Br J Pharmacol 2009; 156:1098-106. [PMID: 19243382 DOI: 10.1111/j.1476-5381.2009.00130.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Changes in smooth muscle tone of the prostate gland are involved in aetiology of symptomatic prostatic hyperplasia, however the control mechanisms of prostatic smooth muscle are not well understood. Here, we have examined the role of internal Ca(2+) compartments in regulating slow wave activity in the guinea pig prostate. EXPERIMENTAL APPROACH Standard intracellular membrane potential recording techniques were used. KEY RESULTS The majority (89%) of impaled cells displayed 'slow wave' activity. Cyclopiazonic acid (10 micromol.L(-1)) transiently depolarized (3-9 mV) the membrane potential of the prostatic stroma and transiently increased slow wave frequency. Thereafter, slow wave frequency slowly decreased over 20-30 min. Ryanodine transiently increased slow wave frequency, although after 30 min exposure slow wave frequency and time course returned to near control values. Caffeine (1 mmol.L(-1)) reduced slow wave frequency, accompanied by membrane depolarization of about 8 mV. Blockade of inositol trisphosphate receptor (IP(3)R)-mediated Ca(2+) release with 2-aminoethoxy-diphenylborate (60 micromol.L(-1)) or Xestospongin C (3 micromol.L(-1)) or inhibiting phospholipase C and IP(3) formation using U73122 (5 micromol.L(-1)) or neomycin (1 and 4 mmol.L(-1)) reduced slow wave frequency, amplitude and duration. The mitochondrial uncouplers, p-trifluoromethoxy carbonyl cyanide phenyl hydrazone (1-10 micromol.L(-1)), carbonyl cyanide m-chlorophenylhydrazone (1-3 micromol.L(-1)) or rotenone (10 micromol.L(-1)), depolarized the membrane (8-10 mV) before abolishing electrical activity. CONCLUSION AND IMPLICATIONS These results suggest that slow wave activity was dependent on the cyclical release of Ca(2+) from IP(3)-controlled internal stores and mitochondria. This implies that intracellular compartments were essential in the initiation and/or maintenance of the regenerative contractile activity in the guinea pig prostate gland.
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Affiliation(s)
- Betty Exintaris
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Parkville, Victoria 3052, Australia.
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Demaurex N, Poburko D, Frieden M. Regulation of plasma membrane calcium fluxes by mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:1383-94. [PMID: 19161976 DOI: 10.1016/j.bbabio.2008.12.012] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2008] [Revised: 12/21/2008] [Accepted: 12/29/2008] [Indexed: 11/27/2022]
Abstract
The role of mitochondria in cell signaling is becoming increasingly apparent, to an extent that the signaling role of mitochondria appears to have stolen the spotlight from their primary function as energy producers. In this chapter, we will review the ionic basis of calcium handling by mitochondria and discuss the mechanisms that these organelles use to regulate the activity of plasma membrane calcium channels and transporters.
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Affiliation(s)
- Nicolas Demaurex
- Department of Cell Physiology and Metabolism, University of Geneva, 1, rue Michel-Servet, CH-1211 Geneva 4, Switzerland
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Hacker K, Medler KF. Mitochondrial calcium buffering contributes to the maintenance of Basal calcium levels in mouse taste cells. J Neurophysiol 2008; 100:2177-91. [PMID: 18684902 DOI: 10.1152/jn.90534.2008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Taste stimuli are detected by taste receptor cells present in the oral cavity using diverse signaling pathways. Some taste stimuli are detected by G protein-coupled receptors (GPCRs) that cause calcium release from intracellular stores, whereas other stimuli depolarize taste cells to cause calcium influx through voltage-gated calcium channels (VGCCs). Although taste cells use two distinct mechanisms to transmit taste signals, increases in cytosolic calcium are critical for normal responses in both pathways. This creates a need to tightly control intracellular calcium levels in all transducing taste cells. To date, however, the mechanisms used by taste cells to regulate cytosolic calcium levels have not been identified. Studies in other cell types have shown that mitochondria can be important calcium buffers, even during small changes in calcium loads. In this study, we used calcium imaging to characterize the role of mitochondria in buffering calcium levels in taste cells. We discovered that mitochondria make important contributions to the maintenance of resting calcium levels in taste cells by routinely buffering a constitutive calcium influx across the plasma membrane. This is unusual because in other cell types, mitochondrial calcium buffering primarily affects large evoked calcium responses. We also found that the amount of calcium that is buffered by mitochondria varies with the signaling pathways used by the taste cells. A transient receptor potential (TRP) channel, likely TRPV1 or a taste variant of TRPV1, contributes to the constitutive calcium influx.
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Affiliation(s)
- Kyle Hacker
- Department of Biological Sciences, University at Buffalo, The State University of New York, Buffalo, NY 14260, USA
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Balemba OB, Bartoo AC, Nelson MT, Mawe GM. Role of mitochondria in spontaneous rhythmic activity and intracellular calcium waves in the guinea pig gallbladder smooth muscle. Am J Physiol Gastrointest Liver Physiol 2008; 294:G467-76. [PMID: 18048480 DOI: 10.1152/ajpgi.00415.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Mitochondrial Ca(2+) handling has been implicated in spontaneous rhythmic activity in smooth muscle and interstitial cells of Cajal. In this investigation we evaluated the effect of mitochondrial inhibitors on spontaneous action potentials (APs), Ca(2+) flashes, and Ca(2+) waves in gallbladder smooth muscle (GBSM). Disruption of the mitochondrial membrane potential with carbonyl cyanide 3-chlorophenylhydrazone, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone, rotenone, and antimycin A significantly reduced or eliminated APs, Ca(2+) flashes, and Ca(2+) waves in GBSM. Blockade of ATP production with oligomycin did not alter APs or Ca(2+) flashes but significantly reduced Ca(2+) wave frequency. Inhibition of mitochondrial Ca(2+) uptake and Ca(2+) release with Ru360 and CGP-37157, respectively, reduced the frequency of Ca(2+) flashes and Ca(2+) waves in GBSM. Similar to oligomycin, cyclosporin A did not alter AP and Ca(2+) flash frequency but significantly reduced Ca(2+) wave activity. These data suggest that mitochondrial Ca(2+) handling is necessary for the generation of spontaneous electrical activity and may therefore play an important role in gallbladder tone and motility.
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Affiliation(s)
- Onesmo B Balemba
- Department of Anatomy and Neurobiology, University of Vermont College of Medicine, 89 Beaumont Ave., D406 Given Bldg., Burlington, VT 05405, USA
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Guven A, Lin WY, Leggett RE, Kogan BA, Levin RM, Mannikarottu A. Effect of aging on the response of biochemical markers in the rabbit subjected to short-term partial bladder obstruction. Mol Cell Biochem 2007; 306:213-9. [PMID: 17673951 DOI: 10.1007/s11010-007-9571-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Accepted: 07/16/2007] [Indexed: 01/25/2023]
Abstract
PURPOSE Partial bladder outlet obstruction (PBOO) results in marked biochemical alterations in the bladder. In this study, we focused on comparison of thapsigargin sensitive sarco/endoplasmic reticulum Ca(2+) ATPase activity (SERCA) and Citrate Synthase after short term PBOO in young versus old rabbits. MATERIALS AND METHODS A total of 20 young and 20 mature male rabbits were divided into 4 sub-groups of 5 rabbits each (4 obstructed and 1 sham-control rabbit). The rabbits in the groups were evaluated after 1, 3, 7, and 14 days of obstruction, respectively. The activities of SERCA and citrate synthase were examined as markers for sarcoplasmic reticular calcium storage and release and mitochondrial function, respectively. RESULTS The SERCA activity of bladder body smooth muscle in the young animals increased at 7 and 14 days. For the old rabbits, the SERCA activity decreased significantly by 1 day and remained this level throughout the course of obstruction, and was significantly lower than young at all time periods. The citrate synthase activity in the young animals decreased over the 1-7 days, and then returned toward control level by 14 days following obstruction. In the old animals, citrate synthase activity of bladder body smooth muscle progressively decreased over the course of the study, and was significantly lower in the old than the young animals after 14 days obstructed. CONCLUSION The urinary bladders of the young rabbits have a considerable greater ability to adapt to PBOO than do those of the old rabbits. The deterioration of mitochondrial and SR function may be important mechanisms underlying geriatric voiding dysfunction.
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Affiliation(s)
- Ahmet Guven
- Department of Pediatric Surgery, Gulhane Military Medical Faculty, Ankara, Turkey
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Juan YS, Onal B, Broadaway S, Cosgrove J, Leggett RE, Whitbeck C, De E, Sokol R, Levin RM. Effect of castration on male rabbit lower urinary tract tissue enzymes. Mol Cell Biochem 2007; 301:227-33. [PMID: 17294138 DOI: 10.1007/s11010-007-9415-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2006] [Accepted: 01/19/2007] [Indexed: 10/23/2022]
Abstract
OBJECTIVES The influence of testosterone on the prostate and corpus cavernosum have been studied extensively. However, the influence of testosterone on the lower urinary tract (bladder and urethra) have not been investigated to any great extent. The aim of this study was to determine whether androgen deprivation alters lower urinary tract metabolism. METHODS A total of 16 rabbits were divided into four groups of four rabbits each. Each rabbit in groups 1-3 underwent surgical bilateral castration for duration of 1, 2 , and 4 weeks, and group 4 underwent sham operations. Sections of bladder body and base wall and mucosa, urethra and corpora were isolated, frozen, and stored under liquid nitrogen. The activities of citrate synthase-thapsigargin sensitive Ca(2+) ATPase (Sarco/Endoplasmic Reticulum Ca(2+ )ATPase [SERCA]), and choline acetyl-transferase were examined as markers for mitochondrial function, sarcoplasmic reticular calcium storage and release, and cholinergic nerve function, respectively. RESULTS The activity of SR function indicator, Ca(2+) ATPase was significantly higher in the control corpora than in the control bladder or urethra. Castration resulted in decreased activity in the mitochondria specific enzyme, citrate synthase, the activity of which was greatest in the urethra and lowest in the corpora. Cholinergic nerve density indicator, choline acetyl-transferase activity was greatest in the bladder body and lowest in the urethra. CONCLUSIONS Our data indicate that (1) significant differences exist in the activities of all three enzymes in the various organs associated with the lower urinary tract; and (2) that castration results in significant alterations in the activities of all three enzymes in the bladder body, base, urethra, and corpora.
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Affiliation(s)
- Yung-Shun Juan
- Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung, Taiwan
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McCarron JG, Chalmers S, Bradley KN, MacMillan D, Muir TC. Ca2+ microdomains in smooth muscle. Cell Calcium 2006; 40:461-93. [PMID: 17069885 DOI: 10.1016/j.ceca.2006.08.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 08/23/2006] [Indexed: 02/03/2023]
Abstract
In smooth muscle, Ca(2+) controls diverse activities including cell division, contraction and cell death. Of particular significance in enabling Ca(2+) to perform these multiple functions is the cell's ability to localize Ca(2+) signals to certain regions by creating high local concentrations of Ca(2+) (microdomains), which differ from the cytoplasmic average. Microdomains arise from Ca(2+) influx across the plasma membrane or release from the sarcoplasmic reticulum (SR) Ca(2+) store. A single Ca(2+) channel can create a microdomain of several micromolar near (approximately 200 nm) the channel. This concentration declines quickly with peak rates of several thousand micromolar per second when influx ends. The high [Ca(2+)] and the rapid rates of decline target Ca(2+) signals to effectors in the microdomain with rapid kinetics and enable the selective activation of cellular processes. Several elements within the cell combine to enable microdomains to develop. These include the brief open time of ion channels, localization of Ca(2+) by buffering, the clustering of ion channels to certain regions of the cell and the presence of membrane barriers, which restrict the free diffusion of Ca(2+). In this review, the generation of microdomains arising from Ca(2+) influx across the plasma membrane and the release of the ion from the SR Ca(2+) store will be discussed and the contribution of mitochondria and the Golgi apparatus as well as endogenous modulators (e.g. cADPR and channel binding proteins) will be considered.
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Affiliation(s)
- John G McCarron
- Department of Physiology and Pharmacology, University of Strathclyde, SIPBS, Glasgow, UK.
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Kubota Y, Biers SM, Kohri K, Brading AF. Effects of imatinib mesylate (Glivec) as a c-kit tyrosine kinase inhibitor in the guinea-pig urinary bladder. Neurourol Urodyn 2006; 25:205-210. [PMID: 16425211 DOI: 10.1002/nau.20085] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
AIMS In the gastrointestinal tract, slow wave activity in smooth muscle is generated by the interstitial cells of Cajal (ICC). Detrusor smooth muscle strips of most species show spontaneous contractions which are triggered by action potential bursts, however, the pacemaker mechanisms for the detrusor are still unknown. Recently, ICC-like cells have been found in guinea-pig bladder, using antibodies to the c-kit receptor. We have investigated the effects of Glivec, a c-kit tyrosine kinase inhibitor, on spontaneous action potentials in guinea-pig detrusor and intravesical pressure of isolated guinea-pig bladders. METHODS Changes in the membrane potential were measured in guinea-pig detrusor smooth muscle using conventional microelectrode techniques. Pressure changes in the bladder were recorded using whole organ bath techniques. RESULTS Smooth muscle cells in detrusor muscle bundles exhibited spontaneous action potentials, and spontaneous pressure rises occurred in isolated bladders. Glivec (10 microM) converted action potential bursts into continuous firing with no effects on the shape of individual action potentials. Glivec (>50 microM) reduced the amplitude of spontaneous pressure rises in the whole bladder in a dose dependent manner and abolished spontaneous action potentials in detrusor smooth muscle cells. CONCLUSIONS The results suggest that ICC-like cells may be responsible for generating bursts of action potentials and contractions in detrusor smooth muscle. Drugs inhibiting the c-kit receptor may prove useful for treating the overactive bladder.
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Affiliation(s)
- Yasue Kubota
- University Department of Pharmacology, Oxford, United Kingdom
- Department of Urology, Nagoya City University Medical School, Nagoya, Japan
| | - Suzanne M Biers
- University Department of Pharmacology, Oxford, United Kingdom
| | - Kenjiro Kohri
- Department of Urology, Nagoya City University Medical School, Nagoya, Japan
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Kubota Y, Kajioka S, Biers SM, Yokota E, Kohri K, Brading AF. Investigation of the effect of the c-kit inhibitor Glivec on isolated guinea-pig detrusor preparations. Auton Neurosci 2005; 115:64-73. [PMID: 15507407 DOI: 10.1016/j.autneu.2004.08.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2004] [Revised: 08/21/2004] [Accepted: 08/23/2004] [Indexed: 11/24/2022]
Abstract
In order to assess the possible role of the c-kit positive cells in the bladder, the effects of c-kit tyrosine kinase inhibitor, Glivec, on spontaneous excitation and ion channel activity in detrusor smooth muscles of the guinea-pig bladder were investigated using intracellular microelectrodes, isometric muscle tension recordings and patch clamp techniques. Glivec (10 microM) converted action potential bursts into continuous firing without affecting their shape but at 50 microM abolished spontaneous action potentials. It had little effect on inward and outward currents at <10 microM, but inhibited them at >50 microM. Glivec decreased the amplitude of spontaneous contractions dose dependently. These results suggest that c-kit positive cells may play a role in modulating spontaneous electrical and mechanical activities. Drugs inhibiting the c-kit receptor may provide a new approach for treating the overactive bladder.
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Affiliation(s)
- Yasue Kubota
- University Department of Pharmacology, Mansfield Road, Oxford OX1 3QT, United Kingdom.
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Poburko D, Lee CH, van Breemen C. Vascular smooth muscle mitochondria at the cross roads of Ca2+ regulation. Cell Calcium 2004; 35:509-21. [PMID: 15110141 DOI: 10.1016/j.ceca.2004.01.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Accepted: 01/25/2004] [Indexed: 11/22/2022]
Abstract
Mitochondria play an essential role in the regulation of vascular smooth muscle Ca(2+) signaling being simultaneously integrated in the regulation of ion channels and Ca(2+) transporters, oxygen radical production, metabolite recycling and intracellular redox potential. Mitochondria buffer Ca(2+) from cytoplasmic microdomains to alter the spatio-temporal pattern of Ca(2+) gradients following Ca(2+)-influx and Ca(2+)-release, and thus control site-specific, Ca(2+)-dependent ion channel activation and inactivation. The sub-cellular localization of mitochondria in conjunction with tissue-specific channel expression is fundamental to vascular heterogeneity. The mitochondrial electron transport chain recycles metabolic intermediates that modulate cellular redox potential and produces oxygen radicals in proportion to oxygen tension. Perturbation of specific complexes within the transport chain can affects NADH:NAD and ATP:ADP ratios and radical production, which can in turn influence second messenger metabolism, ion channel gating and Ca(2+)-transporter activity. Mitochondria thus provide the common ground for cross-talk between these regulatory systems that are mutually sensitive to one another. This cross-talk between signaling systems provides a means to render the physiological regulation of vascular tone responsive to complex stimulation by paracrine and endocrine factors, blood pressure and flow, tissue oxygenation and metabolic state.
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Affiliation(s)
- Damon Poburko
- The Department of Pharmacology and Therapeutics, The University of British Columbia, Vancouver, BC, Canada
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