benzofurans and Pheochromocytoma

To study the protective effect and mechanism of salvianolic acid B (Sal B) on glutamate-induced excito-toxicity.. Glutamate-induced PC12 cell injury model was established to detect the cell survival rate by MTT, the leakage rate of lactic dehydrogenases using LDH, and the cell apoptosis by using AO/EB double staining for fluorescence microscope and PI single staining flow cytometry which was also used to detect the content of intracellular reactive oxygen species. The expression of Caspase-3 protein was also detected by the Western blotting method.. Sal B is proved to inhibit glutamate-induced PC12 cells from injury and prevent them from releasing LDH within the range from 50 micromol x L(-1) to 200 micromol x L(-1). Meanwhile, Sal B has an effect on significantly reducing the expression of inhibit glutamate-induced active Caspase-3 protein, inhibiting accumulated glutamate-induced ROS and decreasing PC12 cell apoptosis rate within the range from 50 micromol x L(-1) to 200 micromol x L(-1).. The study proves that Sal B prevented against glutamate-induced cell injury via inhibiting ROS formation and Caspase-3 pathway-dependent apoptosis in PC12 cells.

Topics: Action Potentials; Animals; Apoptosis; Benzofurans; Caspase 3; Cell Proliferation; Drugs, Chinese Herbal; Excitatory Amino Acid Antagonists; Glutamic Acid; Lactate Dehydrogenases; PC12 Cells; Pheochromocytoma; Rats; Reactive Oxygen Species

Depolarization of plasma membrane potential has a potent inhibitory effect on divalent cation influx catalyzed by the carboxylic ionophores ionomycin and A23187. This effect is observed in different cell models and does not depend on either inhibition of Ca2+-activated cation channels or activation of Ca2+ extrusion mechanisms as suggested previously. A dependence of divalent cation influx on the magnitude of membrane potential is observed also in artificial liposomes. The inhibition of ionophore-dependent divalent cation transport by membrane potential depolarization can be modified varying the ionophore concentration and the external pH. These findings suggest that both neutral and positively charged ionophore-cation complexes can cross the plasma membrane and that their contribution to the overall transport process can be varied according to the experimental conditions.

Topics: Adrenal Gland Neoplasms; Animals; Benzofurans; Calcimycin; Calcium; Calcium Channels; Cations, Divalent; Cations, Monovalent; Cell Line; Chlorides; Fluorescent Dyes; Fura-2; Gramicidin; Ionomycin; Kinetics; Liposomes; Manganese; Manganese Compounds; Mathematics; Membrane Potentials; Models, Theoretical; Pheochromocytoma; Rats

We studied the action of bradykinin (BK) on ionic currents in fused pheochromocytoma PC12 cells under voltage-clamp in whole-cell mode, and on intracellular calcium using fura-2 BK induced the development of an outward current associated with an increase in intracellular calcium, followed by inhibition of an M-like current. The outward current was blocked by (+)-tubocurarine, and prevented when the calcium BAPTA or high concentrations of inositol 1,4,5-triphosphate were introduced into the cell, whereas the M-like current and its inhibition by BK remained unaffected. The protein kinase activator phorbol 12,13 dibutyrate partially reduced the M-current. M-current density did not substantially change after prolonged treatment with nerve growth factor.

Topics: Animals; Benzofurans; Bradykinin; Calcium; Electric Conductivity; Fluorescent Dyes; Fura-2; Intracellular Membranes; Membrane Potentials; Muscarine; Pheochromocytoma; Potassium Channels; Protein Kinase C; Rats; Tumor Cells, Cultured

Accumulation of inositol phosphates (Ins-Ps, revealed by high performance liquid chromatography), changes of the cytosolic free Ca2+ [( Ca2+]i, revealed by fura-2), membrane potential and ionic currents (revealed by bis-oxonol and patch clamping) were investigated in PC12 cells treated with bradykinin (BK). The phenomena observed were (a) due to the activation of a B2 receptor (inhibitor studies) and (b) unaffected by pertussis toxin, cAMP analogs, and inhibitors of either cyclooxygenase or voltage-gated Ca2+ channels. During the initial tens of s, three interconnected events predominated: accumulation of Ins-1,4,5-P3, Ca2+ release from intracellular stores and hyperpolarization due to the opening of Ca2+-activated K+ channels. Phorbol myristate acetate partially inhibited Ins-1,4,5-P3 accumulation at all [BK] investigated, and the [Ca2+]i increase at [BK] less than 50 nM. In PC12 cells treated with maximal [BK] in the Ca2+-containing incubation medium, Ins-1,4,5-P3 peaked at 10 s, dropped to 20% of the peak at 30 s, and returned to basal within 5 min; the peak increase of Ins-1,3,4-P3 was slower and was variable from experiment to experiment, while Ins-P4 rose for 2 min, and remained elevated for many min thereafter. Meanwhile, influx of Ca2+ from the extracellular medium, plasma membrane depolarization (visible without delay when hyperpolarization was blocked), and increased plasma membrane conductance were noticed. Evidence is presented that these last three events (which were partially inhibited by phorbol myristate acetate at all [BK]) were due to the activation of a cation influx, which was much more persistent than the elevation of the two Ins-P3 isomers. Our results appear inconsistent with the possibility that in intact PC12 cells the BK-induced activation of cation influx is accounted for entirely by the increases of either Ins-1,3,4-P3 or Ins-1,4,5-P3 (alone or in combination with Ins-1,3,4,5-P4), as previously suggested by microinjection studies in different cell types.

Topics: Adrenal Gland Neoplasms; Animals; Benzofurans; Bradykinin; Calcium; Cell Line; Cell Membrane; Cytosol; Egtazic Acid; Fura-2; Inositol 1,4,5-Trisphosphate; Inositol Phosphates; Kinetics; Membrane Potentials; Pheochromocytoma; Sugar Phosphates; Tetradecanoylphorbol Acetate

The neuroblastoma-like cell line N2A and the pheochromocytoma-like cell line PC12 excrete about 20-25% of the intracellular fluorescent Ca2+ indicator fura-2 during 10 min of incubation at 37 degrees C. The drug probenecid, known to inhibit membrane systems for the transport of organic anions [Cunningham, Israili & Dayton (1981) Clin. Pharmacol. 6, 135-151], inhibited fura-2 excretion in both cell types. However, probenecid also had untoward effects on intracellular Ca2+ homeostasis in N2A and PC12 cells. We therefore tested the drug sulphinpyrazone, another known inhibitor of organic-anion transport systems. Sulphinpyrazone fully inhibited excretion of fura-2 at 250 microM, a concentration one order of magnitude lower than that of probenecid. At this concentration and for incubation times up to 20 min, sulphinpyrazone had no untoward effects on cell viability and metabolic functions. Fura-2 was also loaded into the cytoplasm of N2A cells by permeabilization of the plasma membrane with extracellular ATP. In this case as well, the dye was rapidly released from the cells and the efflux was blocked by sulphinpyrazone. These findings suggest that N2A and PC12 cells possess a membrane system for the transport of the free-acid form of fura-2. This transport system is probably responsible for the excretion of fura-2 from these cells. Incubation of N2A and PC12 cells with sulphinpyrazone may help overcome problems arising in the investigation of [Ca2+]i homeostasis in these cell types.

Topics: Animals; Benzofurans; Biological Transport; Calcium; Cell Line; Cell Membrane Permeability; Fluorescent Dyes; Fura-2; Homeostasis; Neuroblastoma; Pheochromocytoma; Sulfinpyrazone; Tumor Cells, Cultured

The existence and mechanisms of inactivation of voltage-gated Ca2+ channels are important, but still debatable, physiological problems. By using the Ca2+ indicators quin2 and fura-2, we demonstrate that in PC12 cells voltage-gated Ca2+ channels undergo inactivation dependent on both voltage and [Ca2+]i. Inactivation, however, is never complete and a small number of channels remains open during prolonged depolarization, explaining the steady state elevation of [Ca2+]i observed in cells depolarized with high KCl. A close parallel exists between Ca2+ channel inactivation and the transient nature of neurotransmitter release: secretion is rapidly stimulated during the first 30 s of depolarization, when a transient overshoot in [Ca2+]i can be demonstrated, while it is negligible during the following period, despite the persistence of an elevated [Ca2+]i; predepolarization in Ca2+-free medium and subsequent addition of Ca2+ (a condition which allows the development of the voltage inactivation) abolishes the fast phase of secretion, while not modifying the steady state [Ca2+]i eventually attained; and increases in the intracellular Ca2+ buffering decreases the amplitude of the fast secretion phase induced by KCl without altering the steady state [Ca2+]i. We suggest that localized [Ca2+]i gradients form close to the plasma membrane shortly after depolarization and that the [Ca2+]i reached in these regions is the relevant parameter in the regulation of secretion.

Topics: Adrenal Gland Neoplasms; Aminoquinolines; Animals; Benzofurans; Calcium; Dopamine; Fura-2; Ion Channels; Kinetics; Mathematics; Neurotransmitter Agents; Pheochromocytoma; Potassium Chloride; Rats

In the rat pheochromocytoma cell line PC 12, the effects of four volatile anesthetics (halothane, isoflurane, enflurane, methoxyflurane) on the K+-evoked intracellular calcium [( Ca2+]i) rise were investigated using the Ca2+-sensitive fluorescence dye fura-2. The [Ca2+]i rise was depressed, at clinical concentrations, by all anesthetics with almost identical aqueous IC50 values. The study extends to neuronal cells the observation made previously in cardiac tissue that volatile anesthetics may interfere with Ca2+ fluxes through voltage-gated channels.

Topics: Adrenal Gland Neoplasms; Anesthetics; Animals; Benzofurans; Cell Line; Cytoplasm; Enflurane; Fluorescent Dyes; Fura-2; Halothane; Ion Channels; Isoflurane; Methoxyflurane; Pheochromocytoma; Potassium; Rats

A rise of cytosolic Ca2+ is induced by NGF in rat pheochromocytoma PC12 and bovine chromaffin cells investigated (both in suspension and while attached to polyornithine-coated glass slides) by fluorescence techniques (with quin-2 and fura-2). The effect of NGF on [Ca2+]i is delayed (30-40 s of lag phase), slow (t1/2 = 40 s), relatively small (+50-75%) and persistent (over 10 min). It is due to Ca2+ influx (requires extracellular Ca2+ greater than 10 microM) through a pathway different from the voltage-gated Ca2+ channel, possibly accompanied by intracellular Ca2+ redistribution, and might play a messenger role in NGF action.

Topics: Adrenal Gland Neoplasms; Aminoquinolines; Animals; Benzofurans; Calcium; Cattle; Chromaffin System; Cytosol; Epidermal Growth Factor; Fluorescent Dyes; Fura-2; Nerve Growth Factors; Pheochromocytoma; Rats

The anaesthetic management of a patient with a phaeochromocytoma and cardiomyopathy is described. The control of dysrhythmias was the major problem. Ventricular dysrhythmias were treated with lignocaine, and intravenous amiodarone was used to control the supraventricular rhythm disturbances.

Topics: Adrenal Gland Neoplasms; Aged; Amiodarone; Anesthesia, General; Arrhythmias, Cardiac; Benzofurans; Cardiomyopathy, Dilated; Humans; Intraoperative Complications; Male; Pheochromocytoma