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  1. Article: The role of TRPC6 calcium channels and P2 purinergic receptors in podocyte mechanical and metabolic sensing.

    Gyarmati, Georgina / Toma, Ildikó / Izuhara, Audrey / Burford, James L / Shroff, Urvi Nikhil / Papadouri, Stella / Deepak, Sachin / Peti-Peterdi, János

    Physiology international

    2021  

    Abstract: Podocyte calcium (Ca2+) signaling plays important roles in the (patho)physiology of the glomerular filtration barrier. Overactivation of podocyte transient receptor potential canonical (TRPC) channels including TRPC6 and purinergic signaling via P2 ... ...

    Abstract Podocyte calcium (Ca2+) signaling plays important roles in the (patho)physiology of the glomerular filtration barrier. Overactivation of podocyte transient receptor potential canonical (TRPC) channels including TRPC6 and purinergic signaling via P2 receptors that are known mechanosensors can increase podocyte intracellular Ca2+ levels ([Ca2+]i) and cause cell injury, proteinuria and glomerular disease including in diabetes. However, important mechanistic details of the trigger and activation of these pathways in vivo in the intact glomerular environment are lacking. Here we show direct visual evidence that podocytes can sense mechanical overload (increased glomerular capillary pressure) and metabolic alterations (increased plasma glucose) via TRPC6 and purinergic receptors including P2Y2. Multiphoton microscopy of podocyte [Ca2+]i was performed in vivo using wild-type and TRPC6 or P2Y2 knockout (KO) mice expressing the calcium reporter GCaMP3/5 only in podocytes and in vitro using freshly dissected microperfused glomeruli. Single-nephron intra-glomerular capillary pressure elevations induced by obstructing the efferent arteriole lumen with laser-induced microthrombus in vivo and by a micropipette in vitro triggered >2-fold increases in podocyte [Ca2+]i. These responses were blocked in TRPC6 and P2Y2 KO mice. Acute elevations of plasma glucose caused >4-fold increases in podocyte [Ca2+]i that were abolished by pharmacological inhibition of TRPC6 or P2 receptors using SAR7334 or suramin treatment, respectively. This study established the role of Ca2+ signaling via TRPC6 channels and P2 receptors in mechanical and metabolic sensing of podocytes in vivo, which are promising therapeutic targets in conditions with high intra-glomerular capillary pressure and plasma glucose, such as diabetic and hypertensive nephropathy.
    Language English
    Publishing date 2021-12-16
    Publishing country Hungary
    Document type Journal Article
    ZDB-ID 2896288-6
    ISSN 2498-602X
    ISSN 2498-602X
    DOI 10.1556/2060.2021.00205
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Manganese-enhanced MRI in the evaluation of cell-based therapy for myocardial restoration

    Kim Paul J / Toma Ildiko / Wang INing E / Yang Phillip C

    Journal of Cardiovascular Magnetic Resonance, Vol 14, Iss Suppl 1, p P

    2012  Volume 50

    Keywords Diseases of the circulatory (Cardiovascular) system ; RC666-701 ; Specialties of internal medicine ; RC581-951 ; Internal medicine ; RC31-1245 ; Medicine ; R ; DOAJ:Cardiovascular ; DOAJ:Medicine (General) ; DOAJ:Health Sciences
    Language English
    Publishing date 2012-02-01T00:00:00Z
    Publisher BioMed Central
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  3. Article ; Online: Telmisartan in the diabetic murine model of acute myocardial infarction: dual contrast manganese-enhanced and delayed enhancement MRI evaluation of the peri-infarct region.

    Toma, Ildiko / Kim, Paul J / Dash, Rajesh / McConnell, Michael V / Nishimura, Dwight / Harnish, Phillip / Yang, Phillip C

    Cardiovascular diabetology

    2016  Volume 15, Page(s) 24

    Abstract: Background: A novel MRI technique, employing dual contrast manganese-enhanced MRI (MEMRI) and delayed enhancement MRI (DEMRI), can evaluate the physiologically unstable peri-infarct region. Dual contrast MEMRI-DEMRI enables comprehensive evaluation of ... ...

    Abstract Background: A novel MRI technique, employing dual contrast manganese-enhanced MRI (MEMRI) and delayed enhancement MRI (DEMRI), can evaluate the physiologically unstable peri-infarct region. Dual contrast MEMRI-DEMRI enables comprehensive evaluation of telmisartan to salvage the peri-infarct injury to elucidate the underlying mechanism of restoring the ischemic cardiomyopathy in the diabetic mouse model.
    Methods and results: Dual contrast MEMRI-DEMRI was performed on weeks 1, 2, and 4 following initiation of telmisartan treatment in 24 left anterior descendent artery ligated diabetic mice. The MRI images were analyzed for core infarct, peri-infarct, left ventricular end-diastolic, end-systolic volumes, and the left ventricular ejection fraction (LVEF). Transmission electron microscopy (TEM) and real-time PCR were used for ex vivo analysis of the myocardium. Telmisartan vs. control groups demonstrated significantly improved LVEF at weeks 1, 2, and 4, respectively (33 ± 7 %*** vs. 19 ± 5 %, 29 ± 3 %*** vs. 22 ± 4 %, and 31 ± 2 %*** vs 18 ± 6 %, ***p < 0.001). The control group demonstrated significant differences in the scar volume measured by MEMRI and DEMRI, demonstrating peri-infarct injury. Telmisartan group significantly salvaged the peri-infarct injury. The myocardial effects were validated by TEM, which confirmed the presence of the injured but viable cardiomyocyte morphology in the peri-infarct region and by flow cytometry of venous blood, which demonstrated significantly increased circulating endothelial progenitor cells (EPCs).
    Conclusion: The improved cardiac function in ischemic cardiomyopathy of diabetic mice by telmisartan is attributed to the attenuation of the peri-infarct injury by the angiogenic effects of EPCs to salvage the injured cardiomyocytes. Dual-contrast MEMRI-DEMRI technique tracked the therapeutic effects of telmisartan on the injured myocardium longitudinally.
    MeSH term(s) Angiotensin II Type 1 Receptor Blockers/pharmacology ; Animals ; Apoptosis/drug effects ; Benzimidazoles/pharmacology ; Benzoates/pharmacology ; Contrast Media/administration & dosage ; Diabetes Mellitus, Type 2/complications ; Disease Models, Animal ; Endothelial Progenitor Cells/drug effects ; Endothelial Progenitor Cells/metabolism ; Endothelial Progenitor Cells/pathology ; Fibrosis ; Flow Cytometry ; Gadolinium DTPA/administration & dosage ; Magnetic Resonance Imaging/methods ; Manganese/administration & dosage ; Mice, Inbred C57BL ; Mice, Transgenic ; Microscopy, Electron, Transmission ; Myocardial Infarction/blood ; Myocardial Infarction/drug therapy ; Myocardial Infarction/etiology ; Myocardial Infarction/pathology ; Myocardial Infarction/physiopathology ; Myocardium/metabolism ; Myocardium/pathology ; Myocytes, Cardiac/drug effects ; Myocytes, Cardiac/metabolism ; Myocytes, Cardiac/pathology ; Predictive Value of Tests ; Recovery of Function ; Stroke Volume/drug effects ; Time Factors ; Tissue Survival ; Ventricular Function, Left/drug effects
    Chemical Substances Angiotensin II Type 1 Receptor Blockers ; Benzimidazoles ; Benzoates ; Contrast Media ; EVP 1001-1 ; Manganese (42Z2K6ZL8P) ; Gadolinium DTPA (K2I13DR72L) ; telmisartan (U5SYW473RQ)
    Language English
    Publishing date 2016-02-05
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ISSN 1475-2840
    ISSN (online) 1475-2840
    DOI 10.1186/s12933-016-0348-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Activation of the renal renin-angiotensin system in diabetes--new concepts.

    Peti-Peterdi, János / Kang, Jung Julie / Toma, Ildiko

    Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association

    2008  Volume 23, Issue 10, Page(s) 3047–3049

    MeSH term(s) Animals ; Diabetes Mellitus/physiopathology ; Glucose/metabolism ; Humans ; Juxtaglomerular Apparatus/physiopathology ; Models, Biological ; Nephrons/physiopathology ; Paracrine Communication ; Receptors, G-Protein-Coupled/metabolism ; Renin-Angiotensin System/physiology ; Succinic Acid/metabolism
    Chemical Substances Receptors, G-Protein-Coupled ; Succinic Acid (AB6MNQ6J6L) ; Glucose (IY9XDZ35W2)
    Language English
    Publishing date 2008-07-20
    Publishing country England
    Document type Editorial ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 90594-x
    ISSN 1460-2385 ; 0931-0509
    ISSN (online) 1460-2385
    ISSN 0931-0509
    DOI 10.1093/ndt/gfn377
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article: Multiphoton imaging of renal regulatory mechanisms.

    Peti-Peterdi, János / Toma, Ildikó / Sipos, Arnold / Vargas, Sarah L

    Physiology (Bethesda, Md.)

    2009  Volume 24, Page(s) 88–96

    Abstract: Most physiological functions of the kidneys, including the clearance of metabolic waste products, maintenance of body fluid, electrolyte homeostasis, and blood pressure, are achieved by complex interactions between multiple renal cell types and ... ...

    Abstract Most physiological functions of the kidneys, including the clearance of metabolic waste products, maintenance of body fluid, electrolyte homeostasis, and blood pressure, are achieved by complex interactions between multiple renal cell types and previously inaccessible structures in many organ parts that have been difficult to study. Multiphoton fluorescence microscopy offers a state-of-the-art imaging technique for deep optical sectioning of living tissues and organs with minimal deleterious effects. Dynamic regulatory processes and multiple functions in the intact kidney can be quantitatively visualized in real time, noninvasively, and with submicron resolution. This article reviews innovative multiphoton imaging technologies and their applications that provided the most complex, immediate, and dynamic portrayal of renal function-clearly depicting as well as analyzing the components and mechanisms involved in renal (patho)physiology.
    MeSH term(s) Animals ; Biological Transport, Active ; Humans ; Kidney/anatomy & histology ; Kidney/physiology ; Kidney Glomerulus/anatomy & histology ; Kidney Glomerulus/physiology ; Kidney Tubules/physiology ; Microscopy, Fluorescence, Multiphoton ; Renin-Angiotensin System/physiology
    Language English
    Publishing date 2009-04-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2158667-6
    ISSN 1548-9221 ; 1548-9213
    ISSN (online) 1548-9221
    ISSN 1548-9213
    DOI 10.1152/physiol.00001.2009
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Dual contrast CMR for evaluation of telmisartan and amlodipine combination therapy in the diabetic murine myocardial injury model

    Kim Paul J / Gong Yongquan / Ge Xiaohu / Dash Rajesh / Toma Ildiko / Harnish Phillip / Robbins Robert C / Yang Phillip C

    Journal of Cardiovascular Magnetic Resonance, Vol 15, Iss Suppl 1, p P

    2013  Volume 34

    Keywords Diseases of the circulatory (Cardiovascular) system ; RC666-701 ; Specialties of internal medicine ; RC581-951 ; Internal medicine ; RC31-1245 ; Medicine ; R ; DOAJ:Cardiovascular ; DOAJ:Medicine (General) ; DOAJ:Health Sciences
    Language English
    Publishing date 2013-01-01T00:00:00Z
    Publisher BioMed Central
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  7. Article ; Online: Imaging renin content and release in the living kidney.

    Toma, Ildikó / Kang, Jung Julie / Peti-Peterdi, János

    Nephron. Physiology

    2006  Volume 103, Issue 2, Page(s) p71–4

    Abstract: Renin release is the first, and at least initially, the rate-limiting step in the activation of the renin-angiotensin system, which helps to maintain body salt and water balance. Recent advances in our understanding of pathophysiology have generated a ... ...

    Abstract Renin release is the first, and at least initially, the rate-limiting step in the activation of the renin-angiotensin system, which helps to maintain body salt and water balance. Recent advances in our understanding of pathophysiology have generated a renewed interest in the multiple roles of renin and prorenin as a hormone, enzyme, and signaling molecule. The assays available to measure renin content, release and tissue activity are complex, indirect and work with significant internal errors. We developed an imaging approach to directly visualize renin content and study the dynamics of both the release and tissue activity of renin. Our experimental model uses multiphoton fluorescence microscopy, which is ideal for deep optical sectioning of the living renal tissue. Here we review the application of this renin imaging approach to the dissected, in vitro microperfused glomerulus as well as in the intact kidney in vivo.
    MeSH term(s) Animals ; Humans ; Kidney/metabolism ; Microscopy, Fluorescence, Multiphoton ; Renin/metabolism
    Chemical Substances Renin (EC 3.4.23.15)
    Language English
    Publishing date 2006
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 207121-6
    ISSN 1660-2137 ; 1423-0186 ; 2235-3186 ; 1660-8151 ; 0028-2766
    ISSN (online) 1660-2137 ; 1423-0186 ; 2235-3186
    ISSN 1660-8151 ; 0028-2766
    DOI 10.1159/000090622
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: From in vitro to in vivo: imaging from the single cell to the whole organism.

    Kang, Jung Julie / Toma, Ildiko / Sipos, Arnold / Peti-Peterdi, Janos

    Current protocols in cytometry

    2008  Volume Chapter 12, Page(s) Unit 12.12

    Abstract: This unit addresses the applications of fluorescence microscopy and quantitative imaging to study multiple physiological variables of living tissue. Protocols are presented for fluorescence-based investigations ranging from in vitro cell and tissue ... ...

    Abstract This unit addresses the applications of fluorescence microscopy and quantitative imaging to study multiple physiological variables of living tissue. Protocols are presented for fluorescence-based investigations ranging from in vitro cell and tissue approaches to in vivo imaging of intact organs. These include the measurement of cytosolic parameters both in vitro and in vivo (such as calcium, pH, and nitric oxide), dynamic cellular processes (renin granule exocytosis), FRET-based real-time assays of enzymatic activity (renin), physiological processes (vascular contraction, membrane depolarization), and whole organ functional parameters (blood flow, glomerular filtration). Multi-photon microscopy is ideal for minimally invasive and undisruptive deep optical sectioning of the living tissue, which translates into ultra-sensitive real-time measurement of these parameters with high spatial and temporal resolution. With the combination of cell and tissue cultures, microperfusion techniques, and whole organ or animal models, fluorescence imaging provides unmatched versatility for biological and medical studies of the living organism.
    MeSH term(s) Animals ; Cytological Techniques ; Diagnostic Imaging/methods ; Fluorescent Dyes ; Humans ; Methods ; Microscopy, Fluorescence/methods ; Signal Transduction ; Spectrometry, Fluorescence/methods
    Chemical Substances Fluorescent Dyes
    Language English
    Publishing date 2008-04
    Publishing country United States
    Document type Journal Article
    ISSN 1934-9300
    ISSN (online) 1934-9300
    DOI 10.1002/0471142956.cy1212s44
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: In vivo detection and treatment of ischemia-induced cardiac apoptosis using an MRI-detectable molecular probe and an alpha-adrenergic receptor agonist

    Lam Justin / Toma Ildiko / Gong Yongquan / Simpson Paul C / Robbins Robert C / Yang Phillip C / Dash Rajesh

    Journal of Cardiovascular Magnetic Resonance, Vol 14, Iss Suppl 1, p P

    2012  Volume 67

    Keywords Diseases of the circulatory (Cardiovascular) system ; RC666-701 ; Specialties of internal medicine ; RC581-951 ; Internal medicine ; RC31-1245 ; Medicine ; R ; DOAJ:Cardiovascular ; DOAJ:Medicine (General) ; DOAJ:Health Sciences
    Language English
    Publishing date 2012-02-01T00:00:00Z
    Publisher BioMed Central
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: Connexin 30 deficiency impairs renal tubular ATP release and pressure natriuresis.

    Sipos, Arnold / Vargas, Sarah L / Toma, Ildikó / Hanner, Fiona / Willecke, Klaus / Peti-Peterdi, János

    Journal of the American Society of Nephrology : JASN

    2009  Volume 20, Issue 8, Page(s) 1724–1732

    Abstract: In the renal tubule, ATP is an important regulator of salt and water reabsorption, but the mechanism of ATP release is unknown. Several connexin (Cx) isoforms form mechanosensitive, ATP-permeable hemichannels. We localized Cx30 to the nonjunctional ... ...

    Abstract In the renal tubule, ATP is an important regulator of salt and water reabsorption, but the mechanism of ATP release is unknown. Several connexin (Cx) isoforms form mechanosensitive, ATP-permeable hemichannels. We localized Cx30 to the nonjunctional apical membrane of cells in the distal nephron and tested whether Cx30 participates in physiologically important release of ATP. We dissected, partially split open, and microperfused cortical collecting ducts from wild-type and Cx30-deficient mice in vitro. We used PC12 cells as ATP biosensors by loading them with Fluo-4/Fura Red to measure cytosolic calcium and positioning them in direct contact with the apical surface of either intercalated or principal cells. ATP biosensor responses, triggered by increased tubular flow or by bath hypotonicity, were approximately three-fold greater when positioned next to intercalated cells than next to principal cells. In addition, these responses did not occur in preparations from Cx30-deficient mice or with purinergic receptor blockade. After inducing step increases in mean arterial pressure by ligating the distal aorta followed by the mesenteric and celiac arteries, urine output increased 4.2-fold in wild-type mice compared with 2.6-fold in Cx30-deficient mice, and urinary Na(+) excretion increased 5.2-fold in wild-type mice compared with 2.8-fold in Cx30-deficient mice. Furthermore, Cx30-deficient mice developed endothelial sodium channel-dependent, salt-sensitive elevations in mean arterial pressure. Taken together, we suggest that mechanosensitive Cx30 hemichannels have an integral role in pressure natriuresis by releasing ATP into the tubular fluid, which inhibits salt and water reabsorption.
    MeSH term(s) Adenosine Triphosphate/metabolism ; Animals ; Connexin 30 ; Connexins/metabolism ; Epithelial Sodium Channels/metabolism ; Kidney Tubules, Collecting/metabolism ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Natriuresis ; Pressure ; Receptors, Purinergic/metabolism
    Chemical Substances Connexin 30 ; Connexins ; Epithelial Sodium Channels ; Gjb6 protein, mouse ; Receptors, Purinergic ; Adenosine Triphosphate (8L70Q75FXE)
    Language English
    Publishing date 2009-05-28
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 1085942-1
    ISSN 1533-3450 ; 1046-6673
    ISSN (online) 1533-3450
    ISSN 1046-6673
    DOI 10.1681/ASN.2008101099
    Database MEDical Literature Analysis and Retrieval System OnLINE

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