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Intracellular Ca2+ Transients (intracellular + ca2+_transient)
Selected AbstractsCalcium control of gene regulation in rat hippocampal neuronal culturesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 3 2009Giulietta Pinato Blockage of GABA-A receptors in hippocampal neuronal cultures triggers synchronous bursts of spikes initiating neuronal plasticity, partly mediated by changes of gene expression. By using specific pharmacological blockers, we have investigated which sources of Ca2+ entry primarily control changes of gene expression induced by 20,µM gabazine applied for 30,min (GabT). Intracellular Ca2+ transients were monitored with Ca2+ imaging while recording electrical activity with patch clamp microelectrodes. Concomitant transcription profiles were obtained using Affymetrix oligonucleotide microarrays and confirmed with quantitative RT-PCR. Blockage of NMDA receptors with 2-amino-5-phosphonovaleric acid (APV) did not reduce significantly somatic Ca2+ transients, which, on the contrary, were reduced by selective blockage of L, N, and P/Q types voltage gated calcium channels (VGCCs). Therefore, we investigated changes of gene expression in the presence of blockers of NMDA receptors and L, N, and P/Q VGCCs. Our results show that: (i) among genes upregulated by GabT, there are genes selectively dependent on NMDA activation, genes selectively dependent on L-type VGCCs and genes dependent on the activation of both channels; (ii) the majority of genes requires the concomitant activation of NMDA receptors and Ca2+ entry through VGCCs; (iii) blockage of N and P/Q VGCCs has an effect similar but not identical to blockage of L-type VGCCs. J. Cell. Physiol. 220: 727,747, 2009. © 2009 Wiley-Liss, Inc. [source] CREATINE KINASE INHIBITOR IODOACETAMIDE ANTAGONIZES CALCIUM-STIMULATED INOTROPY IN CARDIOMYOCYTESCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 2 2009Jun Ren SUMMARY 1Inhibition of creatine kinase is known to suppress cardiac contractile reserve in intact hearts, although the underlying mechanism has not been elucidated. 2The present study was designed to examine whether cardiac depression induced by creatine kinase inhibition was due to action at the level of the essential contractile element, namely cardiomyocytes. Adult rat cardiomyocytes were perfused with the creatine kinase inhibitor iodoacetamide (90 µmol/L) for 90 min. Mechanical and intracellular Ca2+ properties were evaluated using edge-detection and fluorescence microscopy, respectively. Myocytes were superfused with normal (1.3 mmol/L) or high (3.3 mmol/L) extracellular Ca2+ contractile buffer. Mechanical function was examined, including peak shortening (PS), maximal velocity of shortening/relengthening (±dL/dt), time to 90% PS (TPS90), time to 90% relengthening (TR90) and integration of shortening/relengthening (normalized to PS). Intracellular Ca2+ transients were evaluated using the following indices: resting and rise of fura-2 fluorescence intensity (,FFI) and intracellular Ca2+ decay time constant. 3The results indicate that elevated extracellular Ca2+ stimulated cardiomyocyte positive inotrope, manifested as increased PS, ±dL/dt, area of shortening, resting FFI and ,FFI associated with a shortened TR90 and intracellular Ca2+ decay time constant. High extracellular Ca2+ did not affect TPS90 and area of relengthening. Iodoacetamide ablated high Ca2+ -induced increases in PS, ±dL/dt, area of shortening, resting FFI, ,FFI and shortened TR90 and intracellular Ca2+ decay time constant. Iodoacetamide itself significantly enhanced the area of relengthening and TR90 without affecting other indices. 4Collectively, these data demonstrate that inhibition of creatine kinase blunts high extracellular Ca2+ -induced increases in cardiomyocyte contractile response (i.e. cardiac contractile reserve). [source] Iso-S -petasin, a hypotensive sesquiterpene from Petasites formosanus, depresses cardiac contraction and intracellular Ca2+ transients in adult rat ventricular myocytesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2003Lucy B. Esberg ABSTRACT Petasites formosanus is an indigenous species of the medicinal plant Petasites which has been used to treat hypertension. Both S -petasin and its isoform iso-S -petasin have been shown to be the effective ingredients in P. formosanus. However, their effect on heart function has not been revealed. This study was to examine the effect of iso-S -petasin on cardiac contractile function at the myocyte level. Ventricular myocytes were isolated from adult rat hearts and were stimulated to contract at 0.5 Hz under 1.0 mm extracellular Ca2+. Contractile properties were evaluated using an lonOptix MyoCam system including peak shortening (PS), time to PS (TPS), time to 90% re-lengthening (TR90) and maximal velocity of shortening/re-lengthening (±dL/dt). Intracellular Ca2+ properties were assessed by fura-2 and presented as Ca2+ -induced Ca2+ release (CICR) and intracellular Ca2+ decay. Acute application of iso-S -petasin (10,7 to 10,4 M) elicited a concentration-dependent inhibition in PS and CICR, with maximal inhibitions of 51.0% and 31.0%, respectively. iso-S -petasin also induced a concentration-dependent inhibition of ± dL/dt without affecting TPS, TR90, baseline intracellular Ca2+ level or intracellular Ca2+ decay. Elevation of extracellular Ca2+ from 1.0 mm to 2.7 mm significantly antagonized the iso-S -petasin-induced depression in PS and CICR. These results demonstrated a direct depressant action of iso-S -petasin on ventricular contraction, which may work in concert with its antihypertensive action to reduce the cardiac load. The iso-S -petasin-induced decrease in CICR may play a role in its cardiac depressant effect. [source] Cardiac Overexpression of Alcohol Dehydrogenase Exacerbates Cardiac Contractile Dysfunction, Lipid Peroxidation, and Protein Damage After Chronic Ethanol IngestionALCOHOLISM, Issue 7 2003Kadon K. Hintz Background: Alcoholic cardiomyopathy is manifested as ventricular dysfunction, although its specific toxic mechanism remains obscure. This study was designed to examine the impact of enhanced acetaldehyde exposure on cardiac function via cardiac-specific overexpression of alcohol dehydrogenase (ADH) after alcohol intake. Methods: ADH transgenic and wild-type FVB mice were placed on a 4% alcohol or control diet for 8 weeks. Mechanical and intracellular Ca2+ properties were evaluated in cardiac myocytes. Levels of acetaldehyde, lipid peroxidation, and protein carbonyl formation were determined. Results: FVB and ADH mice consuming ethanol exhibited elevated blood ethanol/acetaldehyde, cardiac acetaldehyde, and cardiac hypertrophy compared with non-ethanol-consuming mice. However, the levels of cardiac acetaldehyde and hypertrophy were significantly greater in ADH ethanol-fed mice than FVB ethanol-fed mice. ADH transgene itself did not affect mechanical and intracellular Ca2+ properties with the exception of reduced resting intracellular Ca2+ and Ca2+ re-sequestration at low pace frequency. Myocytes from ethanol-fed mice showed significantly depressed peak shortening, velocity of shortening/relengthening, rise of intracellular Ca2+ transients, and sarco(endo)plasmic reticulum Ca2+ load associated with similar duration of shortening/relengthening compared with myocytes from control mice. Strikingly, the ethanol-induced mechanical and intracellular Ca2+ defects were exacerbated in ADH myocytes compared with the FVB group except velocity of shortening/relengthening. The lipid peroxidation end products malondialdehyde and protein carbonyl formation were significantly elevated in both livers and hearts after chronic ethanol consumption, with the cardiac lipid and protein damage being exaggerated by ADH transgene. Conclusion: These data suggest that increased cardiac acetaldehyde exposure due to ADH transgene may play an important role in cardiac contractile dysfunctions associated with lipid and protein damage after alcohol intake. [source] 4,-PDD induces Ca2+ influx in human corneal epithelial cells by activating TRPV4 channelsACTA OPHTHALMOLOGICA, Issue 2007S MERGLER Purpose: Transient receptor potential (TRP) isoform expression is evident in human corneal epithelial cells (HCEC-SV40). However, their role in maintaining corneal epithelial homeostasis is not fully understood. We probed for gene and protein expression as well as functional activity of the vanilloid subtype, TRPV4, in immortalized HCEC-SV40 since they elicit Ca2+ dependent regulatory volume decrease (RVD) responses during exposure to a hypotonic challenge. Methods: RT-PCR and Western blotting analyses identified TRPV4 gene and protein expression. Functional activity was assessed based on determining whether the TRPV4 selective agonist, 4,-PDD, induced transients increases in intracellular Ca2+ concentration. Results: Single cell fluorescence imaging results showed that 4,-PDD (3 ,M) increased intracellular Ca2+ concentration. The fura2 fluorescence ratio (f340/f380) was 0.39 ± 0.03578 in the resting state (n = 5). After application of 4,-PDD it increased to 0.904 ± 0.14363 (n = 5; p = 5.72077×10-5). This increase was abolished by the TRP channel blocker ruthenium red or by Ca2+-free Ringer's medium. Conclusions: In conclusion, there is functional TRPV4 expression in HCEC-SV40. TRPV4 expression may provide an osmosensor role to induce RVD behavior during exposure to a hypotonic challenge since this response is mediated through intracellular Ca2+ transients. Supported in part DFG Pl 150/14-1 and NIH, EY04795. CR: none [source] | ||||||||||