Search results for "PHOSPHATE"

Adenylate storage, metabolism and utilization in coelomic cells of the polychaeteNereis virens (Annelida, polychaeta)

1996

Eleocytes are specialized coelomic cells in nereid annelids which assume a central role during germ cell development. They may contain extremely high concentrations of both adenosine monophosphate (AMP) and adenosine diphosphate (ADP) (each >10 μmol/ml of cell vol.), whereas the adenosine triphosphate (ATP) content is comparatively low (0.8 μmol/ml cell vol.).31P nuclear magnetic, resonance (NMR) studies of living eleocytes suggest the compartmentalization of both AMP and ADP in the large acidic vacuole characteristic for this cell type. Eleocytes are thus capable of storing high concentrations of ADP and AMP without inhibiting energy metabolism, by sequestering these compounds in a separat…

Addition of a signal peptide sequence to theα1D-adrenoceptor gene increases the density of receptors, as determined by [3H]-prazosin binding in the m…

2005

1 Both in mammalian tissues and in transfected cells, only low levels of α1D-adrenoceptors are detected in radioligand binding studies. It has been implicated that the comparatively long N-terminal tail of the α1D-adrenoceptor is responsible for the inefficient surface expression of the receptor. 2 In the present study, we created gene constructs for six N-terminally truncated variants of the human α1D-adrenoceptor. These constructs were used to transfect Neuro2A cells. We show that the density of α1D-adrenoceptors, observed by [3H]-prazosin binding, gradually increased with longer truncations of the N-terminus. This seems to indicate that the long N-terminal tail nonspecifically interferes…

8-NH2-Boldine, an Antagonist of α1Aand α1BAdrenoceptors without Affinity for the α1DSubtype: Structural Requirements for Aporphines at α1-Adrenocepto…

2005

Structure-activity analysis of 21 aporphine derivatives was performed by examining their affinities for cloned human alpha (1A), alpha (1B) and alpha (1D) adrenoceptors (AR) using membranes prepared from rat-1 fibroblasts stably expressing each alpha (1)-AR subtype. All the compounds tested competed for [ (125)I]-HEAT binding with steep and monophasic curves. The most interesting compound was 8-NH (2)-boldine, which retains the selective affinity for alpha(1A)-AR (pKi = 6.37 +/- 0.21) vs. alpha(1B)-AR (pKi = 5.53 +/- 0.11) exhibited by 1,2,9,10-tetraoxygenated aporphines, but shows low affinity for alpha(1D)-AR (pKi < 2.5). Binding studies on native adrenoceptors present in rat cerebral cor…

Functional characterization of α1 -adrenoceptor subtypes in vascular tissues using different experimental approaches:a comparative study

2003

The α1-adrenergic responses of rat aorta and tail artery have been analysed measuring the contractility and the inositol phosphate (IP) formation induced by noradrenaline. Three antagonists, prazosin, 5-methylurapidil (α1A selective) and BMY 7378 (α1D selective) have been used in different experimental procedures. Noradrenaline possesses a greater potency inducing contraction and IP accumulation in aorta (pEC50-contraction=7.32±0.04; pEC50-IPs=6.03±0.08) than in the tail artery (pEC50-contraction=5.71±0.07; pEC50-IPs=5.51±0.10). Although the maximum contraction was similar in both tissues (Emax-tail=619.1±55.6 mg; Emax-aorta-698.2±40.8 mg), there were marked differences in the ability of th…

The spasmogenic effects of vanadate in human isolated bronchus

1997

1. Inhalation of vanadium compounds, particularly vanadate, is a cause of occupational bronchial asthma. We have now studied the action of vanadate on human isolated bronchus. Vanadate (0.1 microM-3 mM) produced concentration-dependent, well-sustained contraction. Its -logEC50 was 3.74 +/- 0.05 (mean +/- s.e.mean) and its maximal effect was equivalent to 97.5 +/- 4.2% of the response to acetylcholine (ACh, 1 mM). 2. Vanadate (200 microM)-induced contraction of human bronchus was epithelium-independent and was not inhibited by indomethacin (2.8 microM), zileuton (10 microM), a mixture of atropine, mepyramine and phentolamine (each at 1 microM), or by mast cell degranulation with compound 48/…

P1 and P2 receptors in the rat duodenal smooth muscle

1989

Erythrocytäre Anionenkonzentrationen bei renaler Insuffizienz

1966

In chronic renal insufficiency, concentrations of chloride and inorganic phosphate in human red blood cells are elevated. There is no correlation between serum non-protein nitrogen and the anionic concentrations of red blood cells. Positive correlations exist between corresponding cellular and extracellular anionic concentrations.

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 (ADPβS), and atropine, but unaffected by P2X purinoceptor desensitisation with α,β-methylene ATP (α,β-meATP) and by 2,2-dimethyl…

High temperature neutron diffraction study of sodium di-tin tri-phosphate

1992

Abstract High temperature high resolution neutron diffraction study of the crystal chemistry of NaSn 2 (PO 4 ) 3 has been completed, at four different temperatures, applying the Rietveld method to the experimental neutron diffraction profile of a synthetic crystalline powder. Below the phase transition (∼860 K) the space group has been determined to be R3 which changes to R3c in the high temperature phase. No chemical bond breaks through the transition. The change in temperature makes the SnO 6 polyhedra rotate around the three fold axis in both structures. The PO 4 polyhedra rotate strictly around the two fold axis in the high temperature phase, but around the [0001] direction in the low t…

Experimental and Theoretical Study of SbPO 4 under Compression

2019

SbPO4 is a complex monoclinic layered material characterized by a strong activity of the non-bonding lone electron pair (LEP) of Sb. The strong cation LEP leads to the formation of layers piled up along the a-axis and linked by weak Sb-O electrostatic interactions. In fact, Sb is 4-fold coordination with O similar to what occurs with the P-O coordination, despite the large difference of ionic radii and electronegativity between both elements. Here we report a joint experimental and theoretical study of the structural and vibrational properties of SbPO4 at high pressure. We show that SbPO4 is not only one of the most compressible phosphates but also one of the most compressible compounds of …