The cannabinoid agonist Win55,212-2 inhibits calcium channels by receptor-mediated and direct pathways in cultured rat hippocampal neurons.

The effects of the cannabinoid receptor agonist Win55,212 on Ca2+ channels were studied in rat hippocampal neurons grown in primary culture. Win55,212-2 inhibited whole-cell Ba2+ currents through Ca2+ channels by both CB1 receptor-mediated and direct mechanisms. The concentration dependent inhibition of the current showed two clear phases, a high-affinity receptor-mediated phase (IC50=14+/-2 nM) that was stereoselective and sensitive to a CB1 receptor antagonist, 300 nM SR141716, and a non-saturating phase that was neither stereoselective nor inhibited by SR141716.

CGP37157 modulates mitochondrial Ca2+ homeostasis in cultured rat dorsal root ganglion neurons.

The effects of 7-chloro-3,5-dihydro-5-phenyl-1H-4,1-benzothiazepine-2-on (CGP37157), an inhibitor of mitochondrial Na+/Ca2+ exchange, on depolarization-induced intracellular free Ca2+ concentration ([Ca2+]i) transients were studied in cultured rat dorsal root ganglion neurons with indo-1-based microfluorimetry. A characteristic plateau in the recovery phase of the [Ca2+]i transient resulted from mitochondrion-mediated [Ca2+]i buffering. It was blocked by metabolic poisons and was not dependent on extracellular Ca2+.

The occurrence of ambient temperature-regulated adhesins, curli, and the temperature-sensitive hemagglutinin tsh among avian Escherichia coli.

Escherichia coli establishes a secondary respiratory tract infection in birds following inhalation of contaminated dust and litter particles. Escherichia coli express adhesins under conditions reflective of the ambient temperatures present in poultry houses. These microbial adhesins allow E.

Reduced Ca2+ uptake by mitochondria in pyruvate dehydrogenase-deficient human diploid fibroblasts.

Physiological and pathological Ca2+ loads are thought to be taken up by mitochondria via a process dependent on aerobic metabolism. We sought to determine whether human diploid fibroblasts from a patient with an inherited defect in pyruvate dehydrogenase (PDH) exhibit a decreased ability to sequester cytosolic Ca2+ into mitochondria. Mobilization of Ca2+ stores with bradykinin (BK) increased the cytosolic Ca2+ concentration ([Ca2+]c) to comparable levels in control and PDH-deficient fibroblasts.

Mobilization of Ca2+ from intracellular stores in transfected neuro2a cells by activation of multiple opioid receptor subtypes.

In neuronal cell lines, activation of opioid receptors has been shown to mobilize intracellular Ca2+ stores. In this report, we describe the excitatory actions of opioid agonists on murine neuroblastoma neuro2a cells stably expressing either delta, mu, or kappa opioid receptors. Fura-2-based digital imaging was used to record opioid-induced increases in intracellular Ca2+ concentration ([Ca2+]i).

All-or-none Ca2+ release from intracellular stores triggered by Ca2+ influx through voltage-gated Ca2+ channels in rat sensory neurons.

Ca2+-induced Ca2+ release (CICR) from intracellular stores amplifies the Ca2+ signal that results from depolarization. In neurons, the amplification has been described as a graded process. Here we show that regenerative CICR develops as an all-or-none event in cultured rat dorsal root ganglion neurons in which ryanodine receptors have been sensitized to Ca2+ by caffeine.

Insensitivity of cultured rat cortical neurons to mitochondrial DNA synthesis inhibitors: evidence for a slow turnover of mitochondrial DNA.

Mitochondrial dysfunction is a major contributor to aging and neurodegeneration. Defects in mitochondrial DNA (mtDNA) have been identified in several neuromuscular diseases. Even though there is a high rate of phenotypic expression of mtDNA mutations in the central nervous system and replication of DNA introduces errors, little is known about the replicative activity of mtDNA in the brain.

Adenovirus-induced inclusion body hepatitis in four-day-old broiler breeders.

Two separate parent broiler flocks originating from the same grandparent flock experienced mortalities of 23% and 40%, respectively, in chicks between 1 and 14 days of age. Chicks affected at 4 days of age had tremors, depression, and hypoglycemia. They had pale yellow, swollen, friable livers.

Evaluation of ELISA titers to infectious laryngotracheitis.

Infectious laryngotracheitis (ILT), a highly infectious upper respiratory disease of chickens, can cause serious economic loss in areas where the poultry industry is concentrated. To determine the antibody levels associated with vaccine administration, field challenge, and protection, six groups of 20 specific-pathogen-free leghorn chickens were housed in biosecured isolation units. Individual groups served as either negative controls, vaccinated (one full dose per bird of chicken embryo origin [CEO] administered by the eyedrop method) and challenged (intratracheal administration with USDA strain ILT virus at 10(4.

Prostaglandin E2 increases the proportion of neonatal rat dorsal root ganglion neurons that respond to bradykinin.

Prostaglandins sensitize some nociceptors to noxious mechanical, thermal and chemical stimuli; however, not all nociceptors are sensitized by prostaglandins. We used cultures of dorsal root ganglion neurons from neonatal rats to determine whether prostaglandins differentially alter the responsiveness of populations of neurons to the chemical stimulus bradykinin. Groups of dorsal root ganglion neurons were defined by size of the cell soma and by the presence of immunoreactivity for substance P.

Sequestration of glutamate-induced Ca2+ loads by mitochondria in cultured rat hippocampal neurons.

1. Buffering of glutamate-induced Ca2+ loads in single rat hippocampal neurons grown in primary culture was studied with ratiometric fluorescent Ca2+ indicators. The hypothesis that mitochondria buffer the large Ca2+ loads elicited by glutamate was tested.

Cannabinoid receptor agonists inhibit glutamatergic synaptic transmission in rat hippocampal cultures.

Activation of cannabinoid receptors inhibits voltage-gated Ca2+ channels and activates K+ channels, reminiscent of other G-protein-coupled signaling pathways that produce presynaptic inhibition. We tested cannabinoid receptor agonists for effects on excitatory neurotransmission between cultured rat hippocampal neurons. Reducing the extracellular Mg2+ concentration to 0.

Investigation of bacterial resistance to hatchery disinfectants.

Three commercial chicken hatcheries were sampled for environmental bacteria. Isolated bacteria were tested for resistance to commercial preparations of quaternary ammonia, phenolic, and glutaraldehyde liquid disinfectants. Bacterial isolates were exposed to several disinfectant dilutions bracketing the dilutions recommended by the manufacturer for 5-, 10-, and 15-min exposure periods before subculturing to broth medium.

Modulation of calcium efflux from cultured rat dorsal root ganglion neurons.

The free intracellular Ca2+ concentration ([Ca2+]i) is governed by the balance between the activation of Ca2+ channels and buffering and efflux processes. We tested the hypothesis that Ca2+ efflux pathways are susceptible to modulation. The whole-cell patch-clamp technique was used in combination with Indo-1-based microfluorometry to record Ca2+ current and [Ca2+]i simultaneously from single rat dorsal root ganglion (DRG) neurons grown in culture.

Pharmacologic characterization of refilling inositol 1,4,5-trisphosphate-sensitive Ca2+ stores in NG108-15 cells.

Following mobilization with the inositol 1,4,5-trisphosphate (IP3)-generating agonist bradykinin, Ca2+ stores in neuroblastoma x glioma hybrid, NG108-15 cells require extracellular Ca2+ to refill. The process by which this store refills with Ca2+ was characterized by recording bradykinin-induced intracellular free Ca2+ concentration transients as an index of the degree of refilling of the store. Cyclopiazonic acid, a microsomal Ca2+ ATPase inhibitor, reversibly depleted intracellular Ca2+ stores in these cells, but did not recruit detectable Ca2+ influx, suggesting that these cells lack substantial capacitative Ca2+ entry.

Complete and reversible block by omega-grammotoxin SIA of glutamatergic synaptic transmission between cultured rat hippocampal neurons.

omega-Grammotoxin SIA (omega-GsTx SIA), a peptide isolated from tarantula venom, inhibits synaptosomal Ca2+ influx and neurotransmitter release, and blocks N-, P-, and Q-type voltage-gated Ca2+ channels. The whole-cell patch-clamp was used to record glutamatergic excitatory post-synaptic currents (EPSCs) evoked by extracellular stimulation of presynaptic neurons in primary rat hippocampal cultures. EPSCs displayed rapid kinetics and were blocked by CNQX.

Omega-grammotoxin SIA blocks multiple, voltage-gated, Ca2+ channel subtypes in cultured rat hippocampal neurons.

Omega-Grammotoxin SIA is a peptide isolated from tarantula venom on the basis of its ability to block the voltage-gated Ca2+ channels that mediate glutamate release. To determine the Ca2+ channel subtype selectivity of omega-grammotoxin SIA, whole-cell Ba2+ current (IBa) was measured in cultured rat hippocampal neurons. Selective Ca2+ channel blockers were used to identify components of IBa mediated by Ca2+ channel subtypes.

Glutamate-induced calcium loads: effects on energy metabolism and neuronal viability.

1. Glutamate-induced increases in intracellular free Ca2+ concentration ([Ca2+]i) were recorded from cultured rat hippocampal neurons with single cell microfluorometry. The [Ca2+]i increase did not correlate with glutamate-induced cell death, consistent with the idea that Ca2+ accumulates in an intracellular store, and that loading this store might be toxic.

Intracellular acidification is not a prerequisite for glutamate-triggered death of cultured hippocampal neurons.

Glutamate decreased intracellular pH (pHi) in cultured rat hippocampal neurons. The protonophore, FCCP (1 microM), produced an acidification comparable to that produced by glutamate. Application of glutamate to FCCP-treated cells, returned pHi to resting levels.

Glutamate-induced intracellular acidification of cultured hippocampal neurons demonstrates altered energy metabolism resulting from Ca2+ loads.

1. Glutamate-evoked increases in intracellular free H+ concentration ([H+]i) were recorded from single rat hippocampal neurons grown in primary culture with carboxy SNARF-based dual emission microfluorimetry. The possibility that this acidification resulted from altered energy metabolism was investigated.

Splenic granulomas in broiler chickens produced experimentally by inoculation with Eubacterium tortuosum.

Eubacterium tortuosum, a gram-positive anaerobic filamentous bacillus, was isolated from splenic and hepatic granulomas of a 56-day-old slaughtered chicken. This isolate was injected intravenously into two groups of 2-week-old broiler chickens, which were necropsied 19 days later. Five of 15 chickens injected with 5 x 10(6) colony-forming units of a 48-hour culture of E.

2',3'-Dideoxycytidine alters calcium buffering in cultured dorsal root ganglion neurons.

Mitochondria play a prominent role in shaping intracellular calcium concentration ([Ca2+]i) transients in dorsal root ganglion neurons. Mitochondrial DNA polymerase is inhibited by antiviral compounds such as 2',3'-dideoxycytidine (ddC). Here, we test the hypothesis that ddC can alter mitochondrially mediated Ca2+ buffering in neurons.

U73122 inhibits phospholipase C-dependent calcium mobilization in neuronal cells.

The aminosteroid U73122 inhibited phospholipase C (PLC)-mediated intracellular Ca2+ release in differentiated and undifferentiated NG108-15 cells, as well as rat dorsal root ganglion (DRG) neurons grown in primary culture. 1 microM U73122 blocked bradykinin (BK)-induced increases in the intracellular free Ca2+ concentration ([Ca2+]i) measured in single cells with indo-1-based dual emission microfluorimetry. A close structural analog, U73343, was without effect.

Opioids mobilize calcium from inositol 1,4,5-trisphosphate-sensitive stores in NG108-15 cells.

Opioids elicit an increase in the intracellular free Ca2+ concentration ([Ca2+]i) in neuroblastoma x glioma hybrid NG108-15 cells, which, depending upon growth conditions, results from either Ca2+ influx in differentiated cells or Ca2+ release from internal stores in undifferentiated cells (Jin et al., 1992). In this report we describe fura-2-based digital imaging studies that demonstrate that opioid-evoked Ca2+ release in these cells results from the activation of phospholipase C (PLC) and subsequent mobilization of the inositol 1,4,5-trisphosphate (IP3)-sensitive store.

omega-Grammotoxin blocks action-potential-induced Ca2+ influx and whole-cell Ca2+ current in rat dorsal-root ganglion neurons.

Field-potential stimulation of rat dorsal-root ganglion (DRG) neurons evoked action-potential-mediated transient increases in intracellular free calcium concentration ([Ca2+]i) as measured by indo-1-based microfluorimetry. Field-potential-evoked [Ca2+]i transients were abolished by tetrodotoxin, and their dependence on stimulus intensity exhibited an abrupt threshold. omega-Conotoxin GVIA (omega-CgTx, 100 nM) inhibited action-potential-mediated Ca2+ influx by 79%, while nitrendipine (1 microM) had little effect.