Search results for "ATP"

P2Y-mediated contractile responses in the longitudinal muscle of mouse distal colon: distinct signaling pathways

2008

Activation of P2Y receptors by ATP and by its analogue, ADPbetaS, triggers two calcium signal pathways in the longitudinal muscle of mouse distal col…

2008

Our previous research showed that ATP and adenosine 5'-O-2-thiodiphosphate (ADPbetaS) induce contractile effects in the longitudinal muscle of mouse distal colon via activation of P2Y receptors which are not P2Y(1) or P2Y(12) subtypes. This study investigated the nature of the P2Y receptor subtype(s) and the mechanisms leading to the intracellular calcium concentration increase necessary to trigger muscular contraction. Motor responses of mouse colonic longitudinal muscle to P2Y receptor agonists were examined in vitro as changes in isometric tension. ATP or ADPbetaS induced muscular contraction, which was not affected by P2Y(11) or P2Y(13) selective antagonists. Calcium-free solution or th…

Agonist-specific Ca2+ signaling at P2Y receptors

2008

Evidence that ATP or a related purine is an excitatory neurotransmitter in the longitudinal muscle of mouse distal colon

2007

BACKGROUND AND PURPOSE: This study analysed the contribution of the purinergic system to enteric neurotransmission in the longitudinal muscle of mouse distal colon. EXPERIMENTAL APPROACH: Motor responses to exogenous ATP and to nerve stimulation in vitro were assessed as changes in isometric tension. KEY RESULTS: ATP induced a concentration-dependent contraction, reduced by 4-[[4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-2-pyridinyl]azo]-1,3-benzene disulphonic acid (PPADS), suramin, P2Y purinoreceptor desensitisation with adenosine 5'-O-2-thiodiphosphate (ADPbetaS), and atropine, but unaffected by P2X purinoceptor desensitisation with alpha,beta-methylene ATP (alpha,beta-meATP) an…

1,4-Dihidropiridīnu atvasinājumu nanodaļiņu toksiskuma novērtējums mikroorganismos

2017

1,4 Dihidropiridīnu (1,4 DHP) atvasinājumi ir plaša organisko vielu grupa, kurā arvien tiek sintezēti jauni savienojumi ar plašām pielietojuma iespējām. Jauno savienojumu toksicitātes raksturojums ir nepieciešams, lai paredzētu to pielietojuma iespējas un novērtētu to iedarbību uz vidi un dzīvajiem organismiem. Darbā pielāgota universāla un efektīva atšķaidījumu metode, lai noteiktu deviņu katjono amfifilo 1,4 DHP atvasinājumu toksicitātes robežkoncentrācijas sešām baktērijām un vienam raugam. Papildus noteikta 1,4 DHP atvasinājumu ietekme uz iekššūnas ATP daudzumu, skābekļa patēriņa ātrumu un etīdija bromīda transportu šūnās. Noskaidrojot toksicitātes robežkoncentrācijas un gūstot ieskatu …

Conversion of the Ca2+-ATPase from Rhodospirillum rubrum into a Mg2+-dependent enzyme by 1,N6-etheno ATP

1980

Nucleoside triphosphate hydrolysis of R.rubrum ATPase complexes can be changed from Ca2+-dependence to Mg2+-dependence by replacing ATP with 1,N6-etheno ATP. Four ATPase complexes which have been prepared by different procedures hydrolyze ATP and 1,N6-etheno ATP at different rates in dependence on the added metal ions. These differences allow an easy distinction of the various enzyme forms.

The Arabidopsis heavy metal P-type ATPase HMA5 interacts with metallochaperones and functions in copper detoxification of roots

2005

*† ‡ § Summary Since copper (Cu) is essential in key physiological oxidation reactions, organisms have developed strategies for handling Cu while avoiding its potentially toxic effects. Among the tools that have evolved to cope with Cu is a network of Cu homeostasis factors such as Cu-transporting P-type ATPases that play a key role in transmembrane Cu transport. In this work we present the functional characterization of an Arabidopsis Cutransporting P-type ATPase, denoted heavy metal ATPase 5 (HMA5), and its interaction with Arabidopsis metallochaperones. HMA5 is primarily expressed in roots, and is strongly and specifically induced by Cu in whole plants. We have identified and characteriz…

Acid sensitivity of neomycin-resistant mutants ofOenococcus oeni: a relationship between reduction of ATPase activity and lack of malolactic activity

1999

Mutants of Oenococcus oeni were isolated as spontaneous neomycin-resistant mutants. Three of these mutants harbored a significantly reduced ATPase activity that represented 50% of that of the wild-type strain. Their growth rates were also impaired at pH 5.3 (46-86% of the wild-type level). However, the profiles of sugar consumption appeared identical to those of the parental strain. At pH 3.2, all the mutant strains failed to grow and a drastic decrease in viability was observed after an acid shock. Surprisingly, all the isolated mutants were devoid of malolactic activity. These results suggest that the ATPase and malolactic activities of O. oeni are linked to each other and play a crucial …

Inhibition of ATP-Binding Cassette Transporters by Chinese Herbs and Phytochemicals

2012

The gene family of ATP-binding cassette (ABC) transporters is widely distributed over the evolutionary tree of life from bacteria to man. In cancer, several ABC transporters are involved in the transport of anticancer drugs. This leads to the development of resistance to a broad spectrum of anticancer agents, termed multidrug resistance. An attractive strategy to overcome multidrug resistance is to block the transport function of ABC transporters leading to lethal intracellular concentrations of anticancer drugs. Efforts to identify transport inhibitors lead to a huge amount of chemical substances, none of which successfully passed clinical trials in cancer patients because of high toxicity…

Cytotoxicity of cucurbitacin E from Citrullus colocynthis against multidrug-resistant cancer cells

2019

Abstract Background Cucurbitacin E (CuE) is an oxygenated tetracyclic triterpenoid isolated from the fruits of Citrullus colocynthis (L.) Schrad. Purpose This study outlines CuE's cytotoxic activity against drug-resistant tumor cell lines. Three members of ABC transporters superfamily, P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and ABCB5 were investigated, whose overexpression in tumors is tightly linked to multidrug resistance. Further factors of drug resistance studied were the tumor suppressor TP53 and the epidermal growth factor receptor (EGFR). Methods Cytotoxicity assays (resazurin assays) were used to investigate the activity of Citrullus colocynthis and CuE towar…