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At least 217 records · Page 12Linked to original sources
PubMed1989

The actions of a red tide toxin from Ptychodiscus brevis on single sodium channels in mammalian neuroblastoma cells.

The actions of brevetoxin (PbTX-3) were studied on single, voltage-dependent sodium channels and whole-cell currents from the neuroblastoma x glioma cell line NG108-15. Purified PbTX-3 shifted the activation of sodium channels to membrane potentials negative to normal. PbTX-3 did not alter the single-channel mean open lifetime, suggesting that the toxin does not change the rate of sodium channel inactivation from the open state. There was also no change in single-channel conductance. These results indicate that brevetoxin increases sodium current at rest by shifting the voltage dependence of channel activation and that the resulting depolarization is limited by channel inactivation.

Animals↗
PubMed1982

Toxicity of two toxins from the Florida red tide marine dinoflagellate, Ptychodiscus brevis.

The purification and crystallization of T17, a toxin from Ptychodiscus brevis, is reported. The toxicity of this compound and a second toxin known as T34 are compared by i.v., i.p. and oral administration in mice. Both toxins produce symptoms characteristic of muscarnic stimulants; hypersalivation, rhinorrhea and excessive urination and defecation being the most commonly observed. T17, which is orally toxic, is believed to be the agent responsible for Neurotoxic Shellfish Poisoning.

Administration, Oral↗
PubMed1982

Bronchoconstriction caused by Florida red tide toxins.

T17, a toxin purified from laboratory cultures of Florida's redtide organism, Ptychodiscus brevis (formerly Gymnodinium breve), produces bronchoconstriction in anesthetized artificially-ventilated guinea pigs. Bronchoconstriction, measured as a resistance to mechanical pulmonary inflation, was antagonized by atropine, but not by interruption of vagal nerve stimulation or diaphragm dissection.

Animals↗
PubMed1984

Neuromuscular blocking action of two brevetoxins from the Florida red tide organism Ptychodiscus brevis.

The action of Ptychodiscus brevis "brevetoxins" T17 and T34 on rat phrenic nerve-stimulated hemidiaphragm contraction is reported. The potency of T34 is greater than the potency of T17, but both cause a complete block of neuromuscular transmission in the nM to pM concentration ranges. Preparations exposed to low concentrations of T17 can recover in the presence of the toxin, whereas the effects of T34 are irreversible. The initial contracture produced by each is prevented by tetrodotoxin or curare. Neuromuscular block does not appear to be due to acetylcholine depletion, as determined by electron microscope examination of the neuromuscular junctions of blocked preparations. Persistent nerve depolarization is believed to be responsible for the neuromuscular block.

Animals↗
PubMed1984

Specific antibodies directed against toxins of Ptychodiscus brevis (Florida's red tide dinoflagellate).

Specific antibodies directed against Ptychodiscus brevis 'brevetoxins' have been produced in a goat. The haptenic toxin T34 was chemically reduced to toxin T17, covalently-linked to succinic acid via anhydride coupling, and coupled to bovine serum albumin using standard carbodiimide condensation procedures. The hapten coupling efficiency ranged from 10.4 to 13.5 moles of toxin bound per mole of protein. Antibody titers were directly related to the frequency of immunization, and weekly intervals appeared optimum for maintaining adequate titers. [3H]Brevetoxin T17 is displaced in a competitive manner from the antibody-antigen complexes by unlabeled toxin, but the antibodies do not distinguish between T17 and T34. The sensitivity achieved, using purified brevetoxins as competitive inhibitors of [3H]T17 binding, was 600 picograms. The assay linearity ranged from 1.5 to 48 ng.

Animals↗
PubMed1990

Florida red-tide toxins (brevetoxins) produce depolarization of airway smooth muscle.

Crude preparations of brevetoxin (PBTX) produce airway contraction; however, it is not known if this toxin-induced mechanical response is coupled to changes in airway smooth muscle membrane potential. Membrane potentials and contractility of in vitro canine trachealis smooth muscle preparations were simultaneously measured with a microelectrode and microforce transducer before and during exposure to either the crude toxin (0.01-1.2 micrograms/ml), or the purified fractions PBTX-2 or PBTX-3 (0.01-0.07 micrograms/ml). Membrane potentials in cultured airway smooth muscle-reaggregate preparations were similarly studied. Toxins produced concentration-dependent depolarizations and contractions in in vitro preparations. These responses were not obtained in the presence of either the muscarinic blocking agent atropine, the sodium channel blocker tetrodotoxin (TTX), 0 mM extracellular Ca2+, or the Ca2+ channel blocker verapamil. The toxins were without effect in cultured cells, whereas acetylcholine produced depolarizations which were blocked in the presence of atropine, but not TTX. This suggested the presence of functional cholinergic receptors in cultured cells, and the PBTX-induced release of endogenous acetylcholine from peripheral nerve endings in the in vitro airway smooth muscle response.

Acetylcholine↗
PubMed1991

An enzyme immunoassay for the detection of Florida red tide brevetoxins.

A non-competitive solid-phase enzyme immunoassay for detection of brevetoxins in various matrices has been developed. The assay utilizes antibodies raised in a goat against brevetoxin PbTx-3-keyhole limpet hemocyanin conjugates with specific purification of brevetoxin antibodies through protein G and brevetoxin affinity columns, and rabbit anti-goat antibodies covalently linked to horseradish peroxidase. The assay was used specifically to detect brevetoxins in both cell culture and contaminated tissues. Sensitivity of the assay is 0.04 picomolar, and toxin can be quantified from 0.04 pM to 0.4 pM brevetoxin per well in microtiter plates by comparison with standard curves.

Animals↗
PubMed1992

Effect of vehicle on skin penetration and retention of a lipophilic red tide toxin (PbTx-3).

The purpose of this study was to determine the effect of carrier vehicle on the penetration of brevetoxin ([3H]PbTx-3) into skin layers and receptor fluid. Disks of guinea-pig skin were mounted on penetration chambers. Epidermal surfaces were dosed with 0.320 microgram/cm2 of PbTx-3 dissolved in 50 microliters of vehicle [water, methanol, or dimethylsulfoxide (DMSO)]. In vitro skin penetration by PbTx-3 during 24 hr of exposure was 6.2, 2.3 and 26% for water, methanol, and DMSO, respectively (expressed as % of dose applied).

Animals↗
PubMed1996

Radioactivity in two tide-washed marsh areas in the eastern Irish Sea: a radiological assessment.

The doses received by man from exposure to artificial radionuclides deposited onto marsh land during tidal inundation on the English side of the Solway Firth and the Dee Estuary have been assessed. The range of total doses received by the different marsh user groups was similar in both study areas, varying from < 1 microSv year-1 to approximately 55 microSv year-1, with total dose dominated by the contribution from external exposure (generally 80% of the total). The maximum doses in both study areas were received by people working on the marshes and are well below the annual dose limit recommended by ICRP for members of the public (1 mSv year-1). The largest dose estimated (56 microSv year-1) is only 6% of the recommended dose limit.

Animals↗