The calcium channel blockers, 1,4-dihydropyridines, are substrates of the multidrug resistance-linked ABC drug transporter, ABCG2.
AuthorsShukla S, Robey RW, Bates SE, Ambudkar SV,
JournalBiochemistry
PubMed ID16846237
'The human ATP-binding cassette transporter, ABCG2, confers resistance to multiple chemotherapeutic agents and also affects the bioavailability of different drugs. [(125)I]Iodoarylazidoprazosin (IAAP) and [(3)H]azidopine were used for photoaffinity labeling of ABCG2 in this study. We show here for the first time that both of these photoaffinity analogues are transport substrates ... More
Imaging of L-type Ca2+ channels in olfactory bulb neurones using fluorescent dihydropyridine and a styryl dye.
AuthorsSchild D, Geiling H, Bischofberger J
JournalJ Neurosci Methods
PubMed ID8531485
'We have imaged the fluorescence of dihydropyridine-Bodipy (fDHP) in cultured olfactory bulb neurones in order to investigate the subcellular distribution of L-type calcium channels in these neurones. The neurones were stained with both fDHP and the voltage-sensitive styryl dye RH414. The fluorescence emission maxima of these dyes were in the ... More
Calcium channels are involved in calcium oxalate crystal formation in specialized cells of Pistia stratiotes L.
AuthorsVolk GM, Goss LJ, Franceschi VR
JournalAnn Bot (Lond)
PubMed ID15087302
'BACKGROUND AND AIMS: Pistia stratiotes produces large amounts of calcium (Ca) oxalate crystals in specialized cells called crystal idioblasts. The potential involvement of Ca(2+) channels in Ca oxalate crystal formation by crystal idioblasts was investigated. METHODS: Anatomical, ultrastructural and physiological analyses were used on plants, fresh or fixed tissues, or ... More
Studies on ion channel antagonist-binding sites in sunflower protoplasts.
AuthorsVallée N, Brière C, Petitprez M, Barthou H, Souvré A, Alibert G
JournalFEBS Lett
PubMed ID9247154
The cytological location of ion channel antagonist-binding sites was studied in sunflower protoplasts using the fluorescent probes DM-Bodipy-PAA and DM-Bodipy-DHP. The binding specificity of the probes was established by competition experiments with Bepridil, phenylalkylamine (Verapamil) and dihydropyridine (Nifedipine) which are known as calcium and potassium channel antagonists. Quantitative image analysis ... More
Digital photography for the light microscope: results with a gated, video-rate CCD camera and NIH-image software.
AuthorsShaw SL, Salmon ED, Quatrano RS
JournalBiotechniques
PubMed ID8747661
In this report, we describe a relatively inexpensive method for acquiring, storing and processing light microscope images that combines the advantages of video technology with the powerful medium now termed digital photography. Digital photography refers to the recording of images as digital files that are stored, manipulated and displayed using ... More
Distribution of Ca2+ channels on cochlear outer hair cells revealed by fluorescent dihydropyridines.
AuthorsOshima T, Ikeda K, Furukawa M, Ueda N, Suzuki H, Takasaka T
JournalAm J Physiol
PubMed ID8843725
Physiological evidence has shown that cochlear outer hair cells (OHC) possess L-type voltage-dependent Ca2+ channels through which Ca2+ enters the OHC during depolarization. Their subcellular distribution has, however, remained unclear. In this study, the distribution of L-type Ca2+ channels on the basolateral plasma membrane of OHC has been demonstrated by ... More
Inosine reverses the inhibitory effects of the L-type Ca2+ channel antagonist, DM-BODIPY-dihydropyridine, on neuritogenesis in an in vitro rat superior cervical ganglia axotomy model.
AuthorsCook DJ, Kulbatski I, Tator CH
JournalNeurosci Lett
PubMed ID15026152
It has recently been demonstrated that L-type calcium channel antagonism with the fluorescent dihydropyridine DM-BODIPY-dihydropyridine (DMBD) inhibits neurite regeneration in rat superior cervical ganglia (SCG). The neuritogenic effects of inosine have been described in various models and the mechanism is thought to be N-kinase dependent. Because of the final common ... More
Involvement of dihydropyridine-sensitive calcium channels in human dendritic cell function. Competition by HIV-1 Tat.
AuthorsPoggi A, Rubartelli A, Zocchi MR
JournalJ Biol Chem
PubMed ID9516412
The entry of extracellular calcium in leukocytes mediates several cellular processes; however, unlike in excitable tissues, the underlying molecular mechanisms are poorly defined. In this paper we provide phenotypical and biochemical evidence that peripheral blood-derived human dendritic cells express dihydropyridine-sensitive calcium channels. Exposure to the dihydropyridine drug nifedipine, which binds ... More
Mini-dystrophin restores L-type calcium currents in skeletal muscle of transgenic mdx mice.
AuthorsFriedrich O, Both M, Gillis JM, Chamberlain JS, Fink RH
JournalJ Physiol
PubMed ID14594987
L-type calcium currents (iCa) were recorded using the two-microelectrode voltage-clamp technique in single short toe muscle fibres of three different mouse strains: (i) C57/SV129 wild-type mice (wt); (ii) mdx mice (an animal model for Duchenne muscular dystrophy; and (iii) transgenically engineered mini-dystrophin (MinD)-expressing mdx mice. The activation and inactivation properties ... More
Polar localization of a dihydropyridine receptor on living Fucus zygotes.
AuthorsShaw SL, Quatrano RS
JournalJ Cell Sci
PubMed ID8838657
We have used a fluorescently-labeled dihydropyridine (FL-DHP) to vitally stain living Fucus zygotes during the establishment of cell polarity. Localization of FL-DHP is primarily at the plasma membrane and FL-DHP binding is competitively blocked by an unlabeled dihydropyridine. Distribution of FL-DHP is initially symmetrical before fixation of the polar axis, ... More
In vivo labeling of L-type Ca2+ channels by fluorescent dihydropyridines: evidence for a functional, extracellular heparin-binding site.
AuthorsKnaus HG, Moshammer T, Friedrich K, Kang HC, Haugland RP, Glossman H
JournalProc Natl Acad Sci U S A
PubMed ID1314393
We have synthesized and characterized fluorescently labeled dihydropyridines (DHPs) as probes for L-type Ca2+ channels. Racemic as well as (+)- and (-)-1,4-dihydro- 2,6-dimethyl-4-(2-trifluoromethylphenyl)-3,5-pyridinecarboxylic acid 2-(aminoethyl)ethyl ester hydrochlorides were coupled to boron dipyrromethane (Bodipy) derivatives. (4,4-Difluoro-5,7-dimethyl-4-bora-3a,4a-diaza)-3- (s-indacene)propionic acid (DMBodipy)-DHP and (4,4-difluoro-7-styryl-4-bora-3a,4a-diaza)-3-(s-indacene+ ++)propionic acid (STBodipy)-DHP have Kd values in the nanomolar range ... More
Complex molecular mechanism for dihydropyridine binding to L-type Ca(2+)-channels as revealed by fluorescence resonance energy transfer.
AuthorsBerger W, Prinz H, Striessnig J, Kang HC, Haugland R, Glossmann H
JournalBiochemistry
PubMed ID7918406
We analyzed binding-induced changes in the fluorescence properties of the 1,4-dihydropyridine (DHP), DMBODIPY-DHP [(-)-1,4-dihydro-2,6-dimethyl-4-(2-trifluromethylphenyl)- 3,5-pyridinedicarboxylic acid 2-[4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-3- (s-indacene)propionylamino]ethylethyl ester)], to study the molecular mechanisms underlying the interaction of DHPs with the alpha 1-subunit of skeletal muscle L-type Ca2+ channels. The quantum yield of the fluorophore DMBODIPY was similar in solvents ... More
Ion channel clustering enhances weak electric field detection by neutrophils: apparent roles of SKF96365-sensitive cation channels and myeloperoxidase trafficking in cellular responses.
AuthorsKindzelskii AL, Petty HR
JournalEur Biophys J
PubMed ID16044273
We have tested Galvanovskis and Sandblom's prediction that ion channel clustering enhances weak electric field detection by cells as well as how the elicited signals couple to metabolic alterations. Electric field application was timed to coincide with certain known intracellular chemical oscillators (phase-matched conditions). Polarized, but not spherical, neutrophils labeled ... More
Relocalization of the calcium gradient and a dihydropyridine receptor is involved in upward bending by bulging of Chara protonemata, but not in downward bending by bowing of Chara rhizoids.
AuthorsBraun M, Richter P
JournalPlanta
PubMed ID10550622
The localization of cytoplasmic free calcium and a dihydropyridine (DHP) receptor, a putative calcium channel, was recorded during the opposite graviresponses of tip-growing Chara rhizoids and Chara protonemata by using the calcium indicator Calcium Crimson and a fluorescently labeled dihydropyridine (FL-DHP). In upward (negatively gravitropically) growing protonemata and downward (positively ... More
Calcium entry through L-type calcium channels is essential for neurite regeneration in cultured sympathetic neurons.
AuthorsKulbatski I, Cook DJ, Tator CH
JournalJ Neurotrauma
PubMed ID15115609
Previous work showed that a post-neuritotomy rise in [Ca2+]i is required for regeneration. We tested the following hypotheses in cultured sympathetic neurons: (1) blocking L-type channels at the time of injury inhibits regeneration; (2) enhancing Ca2+ entry through L-type Ca2+ channels enhances regeneration; (3) L-type Ca2+ channel distribution is predominantly ... More
L-type calcium channels in the photoreceptor ribbon synapse: localization and role in plasticity.
AuthorsNachman-Clewner M, St Jules R, Townes-Anderson E
JournalJ Comp Neurol
PubMed ID10540354
Calcium (Ca(2+)) influx through voltage-gated Ca(2+)channels stimulates a variety of neural activities, including process outgrowth, neurotransmission, and synaptic plasticity. In general, L-type channels control Ca(2+) influx into the soma and dendrites, whereas other Ca(2+) channel types control presynaptic activities. Neurons that make ribbon synapses, however, are among a select group ... More
Branching points of renal resistance arteries are enriched in L-type calcium channels and initiate vasoconstriction.
AuthorsGoligorsky MS, Colflesh D, Gordienko D, Moore LC
JournalAm J Physiol
PubMed ID7864163
The morphologic structures responsible for the drop in blood pressure along the preglomerular vasculature are not completely defined. Theoretical and videomicroscopic analyses of nonrenal vascular beds implicate bifurcations of resistance arteries as important sites of hemodynamic regulation. These structures contain pacemaker cells sensitive to calcium channel blockers and appear to ... More