共查询到20条相似文献，搜索用时 359 毫秒
1.
The molluscicide Frescon induces irreversible contracture in smooth and cross-striated muscles of the freshwater snail Lymnaea stagnalis. This contracture can be inhibited or reversed by elevated Mg2+ and reduced Ca2+ concentrations, by the heavy metals Ni2+, Co2+, and Mn2+, by the rare earth La3+, and by the calcium channel blocker D-600. The removal of extracellular Ca2+ also prevents the expression of Frescon action. These results are consistent with the hypothesis that Frescon causes an increase in the Ca2+ permeability of the sarcolemma. 相似文献
2.
The molluscicide Frescon (N-(triphenylmethyl)morpholine) induces prolonged, irreversible contractions (contractures) in the isolated heart ventricle, penis retractor, and foot muscles of the aquatic snail Lymnaea stagnalis. It also causes contracture of the penis retractor muscle, but not the heart ventricle, of the terrestrial snail Helix aspersa. Since Frescon-induced contracture is not accompanied by a depolarization of the sarcolemma of Lymnaea heart ventricle muscle cells, it is suggested that the action of this molluscicide is associated with a membrane potential-independent activation of the contractile machinery. The rapid response of Lymnaea musculature to Frescon suggests that the direct contracture-inducing action of this molluscicide could explain its toxicity to the whole animal. 相似文献
3.
The molluscicide Frescon (N-(triphenylmethyl)morpholine) induces prolonged, irreversible contractions (contractures) in the isolated heart ventricle, penis retractor, and foot muscles of the aquatic snail Lymnaea stagnalis. It also causes contracture of the penis retractor muscle, but not the heart ventricle, of the terrestrial snail Helix aspersa. Since Frescon-induced contracture is not accompanied by a depolarization of the sarcolemma of Lymnaea heart ventricle muscle cells, it is suggested that the action of this molluscicide is associated with a membrane potential-independent activation of the contractile machinery. The rapid response of Lymnaea musculature to Frescon suggests that the direct contracture-inducing action of this molluscicide could explain its toxicity to the whole animal. 相似文献
4.
Although the molluscicide Frescon is a strong neurotoxin to the Lymnaea stagnalis central nervous system in vitro, it is probable that the exposure of the whole animal to this molluscicide fails to result in central nervous system abnormalities: Frescon does not appear to reach the brain in sufficient quantity to disrupt its normal activity. However, only those Frescon analogs found to be neurotoxic were molluscicidal, suggesting some related mode, if not site, of action. Frescon and its analogs may act by affecting excitable tissues other than the nervous system (e.g., the snail musculature) by altering certain functional and/or structural membrane properties. 相似文献
5.
Frescon (N-triphenylmethyl morpholine) is a strong neurotoxic agent when applied to the in vitro brain of Lymnaea stagnalis. Ten Frescon analogs were tested in order to determine their degree of neurotoxicity. Nine of the ten analogs were found to be neurotoxic to a greater or lesser degree. Triphenylmethanol (a hydrolysis product of Frescon), however, did not exhibit neurotoxicity. These results form part of an investigation to determine the plausibility of the snail central nervous system being a target for Frescon action. 相似文献
6.
Steven B. Symington Hilliary E. HodgdonRichard K. Frisbie J. Marshall Clark 《Pesticide biochemistry and physiology》2011,99(2):131-139
Isolated rat brain synaptosomes were used to evaluate the action of pyrethroid mixtures on Ca2+ influx and subsequent glutamate release under depolarizing conditions. In equipotent binary mixtures at their respective and/or estimated EC50s with deltamethrin always as one of the two components, cismethrin, λ-cyhalothrin, cypermethrin, esfenvalerate and permethrin were additive and S-bioallethrin, fenpropathrin and tefluthrin were less-than-additive on Ca2+ influx. In binary mixtures with deltamethrin always as one of the two components, esfenvalerate, permethrin and tefluthrin were additive and λ-cyhalothrin was less-than-additive on glutamate release. Binary mixture of S-bioallethrin and cismethrin was additive for both Ca2+ influx and glutamate release. Only a subset of pyrethroids (S-bioallethrin, cismethrin, cypermethrin, and fenpropathrin) in binary mixtures with deltamethrin caused a more-than-additive effect on glutamate release. These binary mixtures were, however, only additive (cismethrin and cypermethrin) or less-than-additive (S-bioallethrin and fenpropathrin) on Ca2+ influx. Therefore, increased glutamate release evoked by this subset of pyrethroids in binary mixture with deltamethrin is not entirely occurring by Ca2+-dependent mechanisms via their action at voltage-sensitive calcium channels. These results suggest that pyrethroids do not share a common mode of toxicity at presynaptic nerve terminals from rat brain and appear to affect multiple target sites, including voltage-sensitive calcium, chloride and sodium channels. 相似文献
7.
Characterization of 11 commercial pyrethroids on the functional attributes of rat brain synaptosomes
The action of 11 commercial pyrethroids on Ca2+ influx and glutamate release was assessed using high-throughput functional assays with rat brain synaptosomes to better understand the mechanistic nature of pyrethroid-induced neurotoxicity and aid in the reassessment of pyrethroids in vivo. Concentration-dependent response curves for each of the non-cyano and α-cyano containing pyrethroids were determined and the data used in a cluster analysis. The previously characterized α-cyano pyrethroids that induce the CS-syndrome (cypermethrin, deltamethrin, and esfenvalerate) increased Ca2+ influx and glutamate release, and clustered with two other α-cyano pyrethroids (β-cyfluthrin and λ-cyhalothrin) that shared these same actions. Previously characterized T-syndrome pyrethroids (bioallethrin, cismethrin, and fenpropathrin) did not share these actions and clustered with two other non-cyano pyrethroids (tefluthrin and bifenthrin) that likewise did not elicit these actions. Our current findings indicate that pyrethroids that have an α-cyano group (with the exception of fenpropathrin) were more potent enhancers of Ca2+ influx and glutamate release under depolarizing conditions than pyrethroids that did not possess this functional group. The collective data set does not support the hypothesis that pyrethroids, as a class, act in a similar fashion at presynaptic nerve terminals. 相似文献
8.
Using intracellular microelectrodes, we studied transmembrane resting and action potentials (AP) of left ventricle papillary muscles isolated from the heart of adult lindane-treated (TMG) and untreated (UMG) male genitor rat offspring, obtained by mating untreated female with males chronically treated and untreated with lindane (2 ppb) trace concentrations through beverage. The AP magnitude and duration (APD) were similar in both groups and their response to low temperature (22 °C) unchanged. Lowering the external Ca2+ concentration from 2.5 to 0.625 mM prolonged APD in the TMG group but not in the UMG group. In the TMG group, (i) cumulative addition of Sr2+ (1 mM) to the physiological solution prolonged APD; (ii) apamin (4 μM) and charybdotoxin (4 μM) prolonged the APD. In conclusion, our data revealed that an altered sensitivity of the Ca2+-induced Ca2+ inactivation of L-type Ca2+ channels and of Ca2+-activated K+ channels to Ca2+ has been transferred to TMG offspring. 相似文献
9.
The herbicides trifluralin, oryzalin, ioxynil, dichlofopmethyl, and dinoseb, and the fungicides chloraniformethan and dichlofluanid inhibited energy-dependent Ca2+ uptake in plant mitochondria at concentrations where they did not inhibit ADP phosphorylation and did not interfere with tubulin polymerization. We suggest as a common mechanism of action for these pesticides the inhibition of the regulation of cytoplasmic free Ca2+ concentration which may in turn lead to many physiological malfunctions. 相似文献
10.
Stephen O. Duke Kevin C. Vaughn R.Don Wauchope 《Pesticide biochemistry and physiology》1985,24(3):384-394
Root-fed or foliar-applied glyphosate [N-(phosphonomethyl) glycine] reduced uptake and translocation of Ca2+ and Mg2+, but not K+, by soybean [Glycine max (L.) Merr. “Hill”] seedlings as measured by atomic absorption spectrometry. Histochemical techniques revealed that cells of secondary roots that were formed after glyphosate treatment were deficient in Ca2+. The relative distribution of Ca2+ in control root and leaf cells was mitochondria > plastids > cytoplasm. Glyphosate severely reduced Ca2+ content and eliminated intracellular concentration of Ca2+ in the mitochondria of both root and leaf cells. Glyphosate had no effects on K+ distribution at the ultrastructural level. These results support the view that glyphosate effects on distribution of divalent metal cations may be related directly or indirectly to the phytotoxicity of the herbicide. 相似文献
11.
为了明确钙离子与东莨菪内酯联合作用的杀螨效果,进而为东莨菪内酯的开发利用提供参考,采用玻片浸渍法测定了钙离子(Ca2+)与东莨菪内酯混用对朱砂叶螨Tetranychus cinnabarinus雌成螨的杀螨毒力,并测定了活体和离体条件下对螨体内Ca2+-ATP酶活性的影响,对Ca2+的增效作用机理进行了初步分析。结果表明:Ca2+与东莨菪内酯联合使用能显著增强东莨菪内酯的杀螨效果,其中联合作用24和48 h的LC50值分别比东莨菪内酯单独处理降低20%和45%;对朱砂叶螨Ca2+-ATP酶活性的测定结果表明,无论在活体还是离体条件下,Ca2+与东莨菪内酯联用均能显著增强对Ca2+-ATP酶的抑制作用,而相同浓度的Ca2+单独作用则对Ca2+-ATP酶活性无影响,这也在一定程度上证明了Ca2+-ATP酶是东莨菪内酯的重要作用靶标之一。 相似文献
12.
A Ca-ATPase highly sensitive to DDT has been found in peripheral nerves of lobster, Homarus americanus. The observed I50 for this Ca-ATPase toward DDT is on the order of 10?9M and has a low temperature quotien. The ATPase seems to work over a wide range of ATP concentrations. It is stimulated by Ca2+ (optimum 0.1 mM) and shows sensitivity to Na+ (optimum 20 mM) and K+ (optimum 20 mM) ions. The fact that it is highly sensitive to ruthenium red (I50 = 10 μM) suggests that the enzyme is a Ca-ATPase and not a Mg-ATPase. Furthermore the enzyme is not a CaMg-ATPase, since the presence of Mg2+ along with Ca2+ ion is not required for its activity. DDT is found to inhibit the process of Ca2+ binding in the axonic membrane only in the presence of ATP. The evidence suggests the important role of the Ca-ATPase in regulating Ca2+ concentrations in the membrane. The possible significance of DDT inhibition of the ATPase is discussed. 相似文献
13.
Vincent L. Salgado Stephen N. Irving Thomas A. Miller 《Pesticide biochemistry and physiology》1983,20(1):100-114
When applied at concentrations of one nM or higher to a house fly larval neuromuscular preparation, deltamethrin (DM) and fenvalerate (FV) greatly increased miniature excitatory postsynaptic potential (mepsp) rate and blocked neuromuscular transmission. The DM-induced mepsp discharge was abolished by tetrodotoxin (TTX), removal of Ca2+ from the saline, or by application of hyperpolarizing stimuli to the nerve, indicating that it was due to depolarization of the presynaptic terminals. Also, in the presence of TTX, K+ depolarization increased mepsp rate at the same external K+ concentration before and after DM treatment, confirming that DM released transmitter by depolarizing the nerve terminals rather than by altering the voltage dependence of transmitter release. The potassium channel blocker tetraethylammonium (TEA) increased mepsp rate somewhat, while aconitine (20 μM), which keeps sodium channels open, increased mepsp rate consistently. Pretreatment of nerves with a subthreshold dose of TEA greatly increased the mepsp rate-increasing activity of DM and aconitine, while a subthreshold level of aconitine did not synergize DM. These observations suggest that DM, like aconitine, depolarized nerves by modifying the sodium channels. Knockdown resistant (kdr) larvae were resistant to the depolarizing action of DM and aconitine but not to that of TEA, indicating that the kdr gene produced a modified sodium channel which was less sensitive to the action of pyrethroids and aconitine. During sustained transmitter release by DM, evoked release gradually declined, resulting in a condition called early block in which spontaneous release was high and release could be evoked by electrotonic depolarization of the nerve terminals, but not by a nerve action potential. Early block was probably due to conduction block in the nerve terminals. Early block eventually gave way to late block, characterized by the decline of spontaneous release to subnormal levels and complete failure of evoked release. After late block, the calcium ionophore X-537A could not release transmitter, suggesting that late block was due to depletion of available transmitter. DM did not have a direct effect upon extrasynaptic muscle membrane. However, after late block, muscles were left insensitive to the putative transmitters glutamate and aspartate when these were bath or iontophoretically applied. A low rate of mepsps persisted after late block, indicating that the muscles were still sensitive to the natural transmitters. 相似文献
14.
R.E.J. Dyball 《Pesticide biochemistry and physiology》1982,17(1):42-47
The isolated rat neurophypophysis, which shows a calcium-dependent hormone release when depolarized in vitro was used as a model system to investigate the effects of the pyrethroids decamethrin and resmethrin on mammalian nervous tissue. Both compounds inhibited neurohypophysial hormone release in response to electrical stimulation, decamethrin being more potent than resmethrin. Decamethrin reduced the hormone content of the neurohypophysis. Resmethrin did not reduce stored hormone significantly and its effects on release were dose dependent. They could be mimicked by raising the [Na+] of the medium but not by lowering the [Ca2+]. Resmethrin had no effect on the release of hormone following depolarization of the tissue with a raised [K+]. The results are consistent with the suggestion that the compounds do not act on the potential-dependent secretion process but rather on the mechanism linking depolarization of the secretory terminals with the arrival of action potentials possibly by interfering with sodium-channel activation and inactivation. 相似文献
15.
Zhi-bin Ma Li-jing Sun Jun-xia Zhao Jing Liu Li-an Wang 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(4):545-556
Two types of Ca2+/calmodulin-dependent protein kinase (CaMK) were found in Magnaporthe oryzae. MgCaMK1 and MgCaMK2 were both cloned and sequenced. High similarities in amino acid sequence to other reported CaMKs in fungi suggested that CaMKs were relatively conserved. Both MgCaMK1 and MgCaMK2 have a serine/threonine protein kinase active site and a calmodulin (CaM)-binding domain. Southern blot analysis showed that MgCaMK1 or MgCaMK2 existed as a single copy in the M. oryzae genome. Subsequently, MgCaMK1 or MgCaMK2 was expressed in Escherichia coli BL21 via a pET-32a (+) plasmid. The purified proteins exhibited protein kinase activity. The autophosphorylation and substrate phosphorylation of MgCaMK1 exhibited a Ca2+/calmodulin-dependent manner, and suggested that it belonged to the group of Ca2+/calmodulin-dependent protein kinases. However, the autophosphorylation and substrate phosphorylation of MgCaMK2 exhibited a Ca2+-dependent manner and suggested that it belonged to the group of Ca2+-dependent protein kinases. 相似文献
16.
The mode of action of DDT and pyrethroids was investigated in the house fly, Musca domestica L, using drug:receptor binding techniques. Both in vivo and in vitro binding studies demonstrated the existence of membrane receptors which bind specifically to [14C]DDT and [14C]cis-permethrin. The receptors show properties to be expected of a critical target site of these insecticides. These include negative temperature correlation with binding, relatively nonsensitivity to DDE, and sensitivity to Ca2+. The receptor sites are readily saturated at 45–90 nM [14C]DDT and have an apparent disassociation constant (Kd) of 12.2 nM. The maximum number of binding sites was estimated to be 17 pmol DDT/mg membrane protein (0.34 pmol/house fly head). Competition studies showed DDT, cis-permethrin, and cypermethrin bind to the same receptor but not at precisely the same site. The addition of Ca2+ to the incubation buffer significantly inhibited the binding of both [14C]DDT and [14C]cis-permethrin, suggesting the receptor binding is Ca2+ sensitive and may have a role in ion conductance. 相似文献
17.
18.
Calcium ion in hydroponic solution with glyphosate [N-phosphonomethyl (glycine)] did not significantly influence the efficacy of the herbicide in reducing growth of soybean (Glycine max) seedlings. Data from atomic absorption spectroscopy studies revealed that glyphosate reduced Ca2+ uptake and translocation, whether supplied alone or with other metal ions. Results with radiolabelled 45Ca2+ indicated that glyphosate severely retards translocation of Ca2+ from the roots to the leaves and cotyledons but the effect is not detectable until 24 h after exposure to glyphosate. Influence du glyphosate sur l'absorption el le mourement de I'ion calcium dans des plantules de soja. L'ion calcium présent dans une solution hydroponique contenant du glyphosate (N-phosphono-methyl (glycine) ne modifie pas dc facon significative I'efficacité de I'herbicide dans son action sur la réduction de croissance de plantules de soya. Des données fournies par la spectroscopie d'absorption atomique montrent que le glyphosate reduit l'absorption et le mouvement des ions Ca2+ seuls ou en présence d'ionsd'autresmétaux. Les résultats obtenus avec des ions marqués 45Ca2+ révèlent que le glyphosate retarde notablement le mouvement des ions Ca2+ entre les racines et les feuilles ou les cotylédons mais cet effct n'est pas détectable avant une péríode de 24h suivant l'exposition au glyphosate. 相似文献
19.
Richard J. Martin Achim Harder Michael Londershausen Peter Jeschke 《Pest management science》1996,48(4):343-349
The cyclic depsipeptide PF1022A, given orally to mice, showed very good anthelmintic activity against Heligmosomoides polygyrus and Heterakis spumosa at 50 mg kg−1. In vitro, PF1022A was very active against Trichinella spiralis and had good activity against Nippostrongylus brasiliensis at 1 μg ml−1. An 18-membered enniatin analogue, JES 1798, showed good activity only against N. brasiliensis at 10 μg ml−1. The optical antipode of PF1022A had poor activity even at 100 μg ml−1. The effects of PF1022A on the membrane potential and input conductance of somatic muscle of Ascaris suum were examined using a two-microelectrode current-clamp technique. PF1022A did not antagonize the effects of the selective nicotinic agonist levamisole. PF1022A and an analogue, JES 1798, but not the PF1022A antipode, produced a small time-dependent increase in input conductance associated with no potential change. The increase in input conductance did not occur in the Cl−-free bathing solution, suggesting that the increase in input conductance was mediated by Cl− ions. The addition of high concentrations of Ca2+ to the preparation after the addition of PF1022A did not lead to production of Ca2+-activated Cl− channels, suggesting that its mode of action was not that of a Ca2+ ionophore. The mechanism by which the cyclic depsipeptide might increase the Cl− conductance is discussed. 相似文献
20.
Steven B. Symington 《Pesticide biochemistry and physiology》2005,82(1):1-15
Isolated presynaptic nerve terminals prepared from whole rat brain were used to evaluate the action of deltamethrin on voltage-sensitive calcium channels by measuring calcium influx and endogenous glutamate release. Deltamethrin-enhanced K+-stimulated calcium influx and subsequent Ca2+-dependent glutamate release. The effect of deltamethrin was concentration-dependent, stereospecific, blocked by ω-conotoxin MVIIC but unaltered in the presence of tetrodotoxin. These results suggest that N-type voltage-sensitive calcium channels are a site of action at the presynaptic nerve terminal. Electrophysiological studies were carried out using rat brain Cav2.2 and β3 subunits coexpressed in Xenopus oocytes to validate such action. Deltamethrin reduced barium peak current in a concentraion-dependent and stereospecific manner, increased the rate of activation, and prolonged the inactivation rate of this channel. These experiments support the conclusion that N-type voltage-sensitive calcium channel operation is altered by deltamethrin. 相似文献