The soluble Ca2+-binding protein parvalbumin (PV) is expressed at high levels in fast-twitch muscles of mice. Deficiency of PV in knockout mice (PV -/-) slows down the speed of twitch relaxation, while maximum force generated during tetanic contraction is unaltered. We observed that PV-deficient fast-twitch muscles were significantly more resistant to fatigue than were the wild type. Thus compo...

Abstract We have investigated the role of Ca2+ accumulation and neuronal injury in cerebellar granule neurons after glutamate receptor overactivation. After the removal of the free cytosolic Ca2+ we identified an extensive second Ca2+ fraction (SCF) that is retained within the neurons after glutamate receptor overactivation. The SCF reaches a plateau within 10 min with the magnitude of this SCF...

Interferon-γ (IFN-γ) ± tumor necrosis factor-α (TNF-α) induces antiproliferation and intracellular Ca2+ store depletion in a human submandibular ductal cell line (HSG), which can be reversed on cytokine removal [A. J. Wu, G. C. Chen, B. J. Baum, and I. S. Ambudkar. Am. J. Physiol. 270 ( Cell Physiol. 39): C514-C521, 1996]. Here we have examined a possible mechanism for the IFN-γ-induced intrace...

Wheat calmodulin (CaM) was labeled at Cys-27 with the sulfhydryl-specific fluorescent probe 2-(4'-maleimidoanilino)-naphthalene-6-sulfonic acid (MIANS), to form MIANS.CaM. In the presence of Ca2+, MIANS.CaM undergoes a large fluorescence increase when it binds myosin light chain kinase (MLCK) and caldesmon (CaD), but little fluorescence change when it binds CaM antagonists or Ca2+. MLCK associa...

Disopyramide produces a contraction of the isolated aortic ring of the rat which is graded, develops slowly, and has a time course similar to the tonic phase of the noradrenaline response. This effect is not modified by alpha-adrenoceptor blockade (yohimbine) but is completely abolished by a Ca2+ antagonist (verapamil) or by removal of Ca2+ from the bathing solution. These results indicate that...

The rate and the total amount of Ca2+ elevation in the presynaptic terminals of bullfrog sympathetic ganglia depend on the firing frequency of the terminals. Carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial uncoupler, was used for testing whether mitochondrial Ca2+ uptake is one of the mechanisms that underlie this frequency dependence. Fura-2 fluorimetry was used for measuremen...

Using microspectrofluorimetry and the calcium-sensitive dye fura-2, we examined the effect of excitatory amino acids on [Ca2+]i in single striatal neurons in vitro. N-methyl-D-aspartic acid (NMDA) produced rapid increases in [Ca2+]i. These were blocked by DL-2-amino-5-phosphonovaleric acid (AP5), by Mg2+, by phencyclidine, and by MK801. The block produced by Mg2+ and MK801 could be relieved by ...

Calmodulin is a ubiquitous Ca2+ binding protein that binds to ryanodine rectors (RyR) and is thought to modulate its activity. Here we evaluated the effects of recombinant calmodulin on the rate of occurrence and spatial properties of Ca2+ sparks as an assay of activation in saponin-permeabilized mouse myofibers. Control myofibers exhibited a time-dependent increase and subsequent decrease in s...

This investigation was undertaken to determine prolonged adverse effects of benzalkonium chloride (BzCl), a cationic surfactant, and sodium dodecyl sulfate (SDS), an anionic surfactant, after an initial treatment of and subsequent removal from a primary culture system of rabbit corneal epithelial cells. Metabolic integrity and cell growth were evaluated at specified periods after a 1-hr treatme...

1. Fura-2 imaging was used to measure the effects of glutamate on caffeine-sensitive Ca2+ stores in neurons of the avian cochlear nucleus, n. magnocellularis (NM). 2. On average, 100-mM caffeine stimulated a 250-nM increase in intracellular calcium ion concentration {[Ca2+]i} in Ca(2+)-free media; 1-mM glutamate significantly attenuated caffeine-stimulated Ca2+ responses. 3. The metabotropic gl...