Patricio J Velez

Learn More
 We describe a high temporal resolution confocal spot microfluorimetry setup which makes possible the detection of fluorescence transients elicited by Ca2+ indicators in response to large (50–200 μM), short duration (<100 ns), free [Ca2+] transients generated by laser flash photolysis of DM-nitrophen (DM-n; caged Ca2+). The equilibrium and kinetic(More)
Inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are channels responsible for calcium release from the endoplasmic reticulum (ER). We show that the anti-apoptotic protein Bcl-2 (either wild type or selectively localized to the ER) significantly inhibited InsP3-mediated calcium release and elevation of cytosolic calcium in WEHI7.2 T cells. This(More)
Single ryanodine-sensitive sarcoplasmic reticulum (SR) Ca2+ release channels isolated from rabbit skeletal and canine cardiac muscle were reconstituted in planar lipid bilayers. Single channel activity was measured in simple solutions (no ATP or Mg2+) with 250 mM symmetrical Cs+ as charge carrier. A laser flash was used to photolyze caged-Ca2+(More)
Bcl-2-related proteins are critical regulators of cell survival that are localized to the outer mitochondrial, outer nuclear and endoplasmic reticulum membranes. Despite their physiological importance, the biochemical function of Bcl-2-related proteins has remained elusive. The three-dimensional structure of Bcl-xL, an inhibitor of apoptosis, was recently(More)
The earliest stages of Huntington disease are marked by changes in gene expression that are caused in an indirect and poorly understood manner by polyglutamine expansions in the huntingtin (HTT) protein. To explore the hypothesis that DNA methylation may be altered in cells expressing mutated HTT, we use reduced representation bisulfite sequencing (RRBS) to(More)
The cardiac muscle isoform of the ryanodine receptor/Ca2+ release channel (RYR) has been proposed to be an important target of cyclic ADP-ribose (cADPR) action in mammalian cells. However, we now demonstrate that neither cADPR (0.1-5 microM), nor the related metabolites beta-NAD+ (0.1-30 mM) and ADP-ribose (0.1-5 microM), affected cardiac RYR activity as(More)
Single channel currents through cardiac sarcoplasmic reticulum (SR) Ca2+ release channels were measured in very low levels of current carrier (e.g., 1 mM Ba2+). The hypothesis that surface charge contributes to these anomalously large single channel currents was tested by changing ionic strength and surface charge density. Channel identity and sidedness was(More)
The actions of three endogenous polyamines (spermine, spermidine, and putrescine) were defined on Ca2+ release channels (ryanodine receptors, RyRs) isolated from rabbit cardiac sarcoplasmic reticulum. The current-voltage relationship of the RyR channel was N-shaped in the presence of polyamine (1-5 mM). Polyamine blocked conduction near 0 mV, but the(More)
mu-Conotoxin (mu-CTX) specifically occludes the pore of voltage-dependent Na(+) channels. In the rat skeletal muscle Na(+) channel (mu1), we examined the contribution of charged residues between the P loops and S6 in all four domains to mu-CTX block. Conversion of the negatively charged domain II (DII) residues Asp-762 and Glu-765 to cysteine increased the(More)
Bay K 8644, an L-type Ca2+ channel agonist, was shown previously to increase resting sarcoplasmic reticulum (SR) Ca2+ loss and convert post-rest potentiation to decay in dog and ferret ventricular muscle. Here, the effects of Bay K 8644 on local SR Ca2+ release events (Ca2+ sparks) were measured in isolated ferret ventricular myocytes, using laser scanning(More)