Separate control of anion and cation transport in malpighian tubules of Drosophila Melanogaster.

1996 ◽  
Vol 199 (5) ◽  
pp. 1163-1175 ◽  
Author(s):  
M J O'Donnell ◽  
J A Dow ◽  
G R Huesmann ◽  
N J Tublitz ◽  
S H Maddrell
Keyword(s):  
Drosophila Melanogaster ◽  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Anion Transport ◽  
Malpighian Tubules ◽  
Potential Profile ◽  
Chloride Permeability ◽  
Principal Cells ◽  
Pass Through

Microelectrode measurements of basal, apical and transepithelial potentials in the Malpighian tubules of Drosophila melanogaster were obtained under a range of conditions in order to investigate whether each of the three main second messenger systems known to act in the tubules (cyclic AMP, cyclic GMP and Ca2+) acted specifically on either cation or anion transport, or whether they activated both systems. Ion-selective microelectrode determinations of K+ concentration and pH of secreted fluid allowed the role of each signalling system to be analysed further. Stimulation with cyclic nucleotides markedly alters the potential profile across principal cells through the selective activation of an apical electrogenic V-ATPase. By contrast, manipulation of extracellular chloride levels, combined with stimulation with leucokinin, does not affect the potential profile across the principal cells, showing that chloride must pass through another route. The cell-permeant Ca2+ chelator BAPTA-AM was shown to suppress the action of leucokinins (insect peptides that induce rapid fluid secretion), but not those of cyclic AMP, the neuronally derived insect peptide cardioacceleratory peptide 2b (CAP2b) or its intracellular messenger cyclic GMP. This shows that leucokinins act through Ca2+ and not through cyclic nucleotides and that the cyclic nucleotide pathways do not co-activate the intracellular Ca2+ pathway to exert their effects. Taken together, these results show that leucokinin acts through intracellular Ca2+, independently of cyclic AMP or cyclic GMP, to raise the chloride permeability of the epithelium. By contrast, either cyclic AMP or cyclic GMP (upon CAP2b stimulation) acts on the electrogenic cation-transporting apical V-ATPase, with only a negligible effect on anion conductance and without perturbing intracellular [Ca2+]. There is thus a clear functional separation between the control pathways acting on cation and anion transport in the tubules. Given the evidence from D. melanogaster and other species that chloride does not pass through the principal cells, we speculate that these two pathways may also be physically separated within cell subtypes of the tubules.

The Drosophila melanogaster homologue of an insect calcitonin-like diuretic peptide stimulates V-ATPase activity in fruit fly Malpighian tubules

2001 ◽  
Vol 204 (10) ◽  
pp. 1795-1804 ◽  
Author(s):  
G.M. Coast ◽  
S.G. Webster ◽  
K.M. Schegg ◽  
S.S. Tobe ◽  
D.A. Schooley
Keyword(s):  
Drosophila Melanogaster ◽  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Fruit Fly ◽  
Transport Processes ◽  
Malpighian Tubules ◽  
Drosophila Genome ◽  
Genome Database

The Drosophila melanogaster homologue of an insect calcitonin-like diuretic hormone was identified in a BLAST search of the Drosophila genome database. The predicted 31-residue amidated peptide (D. melanogaster DH(31); Drome-DH(31)) was synthesised and tested for activity on fruit fly Malpighian tubules. It increases tubule secretion by approximately 35 % of the response obtained with a myokinin from the housefly Musca domestica (muscakinin; Musdo-K) and has an EC(50) of 4.3 nmol l(−)(1). The diuretic activities of Drome-DH(31) and Musdo-K were additive when tested at threshold and supra-maximal concentrations, which suggests that they target different transport processes. In support of this, Drome-DH(31) increased the rate of secretion by tubules held in bathing fluid with a reduced Cl(−) concentration, whereas Musdo-K did so only in the presence of Drome-DH(31). Stimulation with Drome-DH(31) increased the lumen-positive transepithelial potential in the main secretory segment of the tubule. This was attributed to activation of an apical electrogenic proton-translocating V-ATPase in principal cells, since it was associated with hyperpolarisation of the apical membrane potential and acidification of secreted urine by 0.25 pH units. Exogenous 8-bromo-cyclic AMP and cyclic GMP increased tubule secretion to the same extent as Drome-DH(31) and, when tested together with the diuretic peptide, their activities were not additive. Stimulation with Drome-DH(31) resulted in a dose-dependent increase in cyclic AMP production by tubules incubated in saline containing 0.5 mmol l(−)(1) 3-isobutyl-1-methylxanthine, whereas cyclic GMP production was unchanged. Taken together, the data are consistent with Drome-DH(31) activating an apical membrane V-ATPase via cyclic AMP. Since the K(+) concentration of the secreted urine was unchanged, it is likely that Drome-DH(31) has an equal effect on K(+) and Na(+) entry across the basolateral membrane.

Cyclic nucleotides, calcium, bicarbonate, and protein secretion in canine pancreatic juice in response to cholecystokinin–pancreozymin

1979 ◽  
Vol 57 (6) ◽  
pp. 541-546 ◽  
Author(s):  
H. L. Cailla ◽  
H. Sarles ◽  
M. V. Singer
Keyword(s):  
Cyclic Amp ◽  
Pancreatic Juice ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Parallel Increase ◽  
Calcium Bicarbonate ◽  
Strong Linear Correlation ◽  
Protein Output ◽  
Dose Dependent ◽  
Stimulation Of

The secretion of cyclic AMP, cyclic GMP, protein, calcium, and bicarbonate in the pancreatic juice of three nonanesthetized dogs with chronic gastric and duodenal Thomas cannulae has been studied. Intravenous infusions of increasing doses of cholecystokinin–pancreozymin (CCK) (1.5, 3, 6, 12, 24 Crick Harper-Raper (CHR) U kg−1 h−1) were administered together with a continuous submaximal dose of secretin (1 clinical unit (CU) kg−1 h−1). Doubling CCK doses every 45 min induced a parallel increase in the output of both cyclic nucleotides. Cyclic AMP output peaked at between 15 and 30 min for 3 and 6 U kg−1 h−1 of CCK and later for 12 and 24 U kg−1 h−1 of CCK whereas cyclic GMP output increased more constantly. Calcium output followed a pattern similar to that of cyclic GMP secretion. Flow rate and protein output attained their peaks at between 30 and 45 min. A strong linear correlation was found between the quantities of cyclic AMP, cyclic GMP, and the quantities of protein secreted in response to each CCK dose. This study demonstrates the presence of cyclic GMP in the canine pancreatic juice and the dose-dependent stimulation of the secretion of cyclic GMP and cyclic AMP by CCK in the presence of secretin.

Novel aspects of the transport of organic anions by the malpighian tubules of Drosophila melanogaster

2000 ◽  
Vol 203 (23) ◽  
pp. 3575-3584 ◽  
Author(s):  
S.M. Linton ◽  
M.J. O'Donnell
Keyword(s):  
Drosophila Melanogaster ◽  
Organic Acid ◽  
Organic Anion ◽  
Indigo Carmine ◽  
Organic Anions ◽  
Malpighian Tubules ◽  
Principal Cells ◽  
Anion Transporters ◽  
Mode Of Transport

Para-aminohippuric acid (PAH) is a negatively charged organic ion that can pass across the epithelium of Malpighian tubules. Its mode of transport was studied in Malpighian tubules of Drosophila melanogaster. PAH transport was an active process, with a K(m) of 2. 74 mmol l(−)(1) and a V(max) of 88.8 pmol min(−)(1). Tubules had a low passive permeability to PAH, but PAH transport rates (832 nmol min(−)(1)mm(2)) and concentrative ability ([PAH](secreted fluid):[PAH](bath)=81.2) were the highest measured to date for insects. Competition experiments indicated that there were two organic anion transporters, one that transports carboxylate compounds, such as PAH and fluorescein, and another that transports sulphonates, such as amaranth and Indigo Carmine. PAH transport appears to be maximal in vivo because the rate of transport by isolated tubules is not increased when these are challenged with cyclic AMP, cyclic GMP, leucokinin I or staurosporine. Basolateral PAH transport was inhibited by ouabain and dependent on the Na(+) gradient. The Malpighian tubules appeared not to possess an organic acid/ α -keto acid exchanger because PAH accumulation was not affected by low concentrations (100 μmol l(−)(1)) of α -keto acids (α -ketoglutarate, glutarate, citrate and succinate) or the activity of phosphokinase C. PAH transport may be directly coupled to the Na(+) gradient, perhaps via Na(+)/organic acid cotransport. Fluorescence microscopy showed that transport of the carboxylate fluorescein was confined to the principal cells of the main (secretory) segment and all the cells of the lower (reabsorptive) segment. Organic anions were transported across the cytoplasm of the principal cells both by diffusion and in vesicles. The accumulation of punctate fluorescence in the lumen is consistent with exocytosis of the cytoplasmic vesicles. Apical PAH transport was independent of the apical membrane potential and may not occur by an electrodiffusive mechanism.

scholarly journals The Role of Cyclic Nucleotides in the CNS

1977 ◽  
Vol 4 (3) ◽  
pp. 151-195 ◽  
Author(s):  
John W. Phillis
Keyword(s):  
Cyclic Amp ◽  
Synaptic Transmission ◽  
Cyclic Gmp ◽  
Adenosine Receptor ◽  
Cyclic Nucleotides ◽  
Phosphodiesterase Inhibitors ◽  
Adenosine Uptake ◽  
Injection Techniques ◽  
Firm Basis

SUMMARY:On the basis of the information presented in this review, it is difficult to reach any firm decision regarding the role of cyclic AMP (or cyclic GMP) in synaptic transmission in the brain. While it is clear that cyclic nucleotide levels can be altered by the exposure of neural tissues to various neurotransmitters, it would be premature to claim that these nucleotides are, or are not, essential to the transmission process in the pre- or postsynaptic components of the synapse. In future experiments with cyclic AMP it will be necessary to consider more critically whether the extracellularly applied nucleotide merely provides a source of adenosine and is thus activating an extracellularly located adenosine receptor, or whether it is actually reaching the hypothetical sites at which it might act as a second messenger. The application of cyclic AMP by intracellular injection techniques should minimize this particular problem, although possibly at the expense of new difficulties. Prior blockade of the adenosine receptor with agents such as theophylline or adenine xylofuranoside may also assist in the categorization of responses to extracellularly applied cyclic AMP as being a result either of activation of the adenosine receptor or of some other mechanism. Ultimately, the development of highly specific inhibitors for adenylate cyclase should provide a firm basis from which to draw conclusions about the role of cyclic AMP in synaptic transmission. Similar considerations apply to the actions of cyclic GMP and the role of its synthesizing enzyme, guanylale cyclase.The use of phosphodiesterase inhibitors in studies on cyclic nucleotides must also be approached with caution. The diverse actions of many of these compounds, which include calcium mobilization and block of adenosine uptake, could account for many of the results that have been reported in the literature.

scholarly journals THE MODULATING INFLUENCE OF CYCLIC NUCLEOTIDES UPON LYMPHOCYTE-MEDIATED CYTOTOXICITY

1973 ◽  
Vol 138 (2) ◽  
pp. 381-393 ◽  
Author(s):  
Terry B. Strom ◽  
Charles B. Carpenter ◽  
Marvin R. Garovoy ◽  
K. Frank Austen ◽  
John P. Merrill ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Adenylate Cyclase ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Prostaglandin E1 ◽  
Cell Interaction ◽  
Target Cells ◽  
Cholinergic Stimulation ◽  
Initial Cell ◽  
Initial Interaction

The capacity of allosensitized thymus-derived lymphocytes to destroy target cells bearing donor alloantigens is modulated by the cellular levels of cyclic AMP and cyclic GMP. Increases in the cyclic AMP levels of attacking lymphocytes by stimulation with prostaglandin E1, isoproterenol, and cholera toxin inhibit lymphocyte-mediated cytotoxicity; whereas, depletion of cyclic AMP with imidazole enhances cytotoxicity. The augmentation of cytotoxicity produced by cholinergic stimulation with carbamylcholine is not associated with alterations in cyclic AMP levels and is duplicated by 8-bromo-cyclic GMP. The effects of activators of adenylate cyclase, cholinomimetic agents, and 8-bromocyclic GMP are upon the attacking and not the target cells and occur at the time of initial interaction of attacking and target cells. Indeed, the level of cyclic nucleotide (cyclic AMP and cyclic GMP) at the time of initial cell-to-cell interaction determines the extent of cytotoxicity.

scholarly journals Growth hormone, cyclic nucleotides and the rapid control of translation in heart muscle

1975 ◽  
Vol 152 (3) ◽  
pp. 583-592 ◽  
Author(s):  
J Mowbray ◽  
J A Davies ◽  
D J Bates ◽  
C J Jones
Keyword(s):  
Growth Hormone ◽  
Protein Synthesis ◽  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Cyclic Nucleotide ◽  
Precursor Pool ◽  
Growth Hormone Action ◽  
Constant Rate ◽  
The Individual

Perfused rat heart incorporated L-[14C]tyrosine into protein at a constant rate for up to 75 min. A purified bovine growth-hormone preparation (1 mug/ml) stimulated the incorporation to a new constant rate that was more than three times the control rate by 10 min after hormone addition to perfusate. The hormone, however, did not alter the intracellular tracer amino acid pool, and the relationship of this to the aminoacyl-tRNA precursor pool is discussed. It is concluded that the increased incorporation largely reflected a rapid increase in protein synthesis at the ribosomes. Measurements of cyclic nucleotide contents during the perfusion showed that these appeared to vary in a systematic way during the perfusion. This strands in contrast with the constant values given by several other parameters measured in this preparation. Futher, the cyclic nucleotide variation seems to be independent of external effectors. The steady-state performance of the heart correlates more closely the [cyclic AMP]/[cyclic GMP] ratio than with the content of the individual cyclic nucleotides. At 10 min after the addition of growth hormone a slight decrese in cyclic AMP content and a large decrease in cyclic GMP were found, suggesting that the hormone's effect in stimulating protein synthesis may be mediated by a decrease in cyclic nucleotide concentrations or an increase in the [cyclic AMP]/[cyclic |p] ratio. The findings are also consistent with an intracellularly directed role for these nucleotides, and the possibility that the cyclic nucleotide changes are an indirect result of growth-hormone action is discussed.

scholarly journals Immunofluorescent localization of cyclic nucleotide-dependent protein kinases on the mitotic apparatus of cultured cells.

1980 ◽  
Vol 87 (2) ◽  
pp. 336-345 ◽  
Author(s):  
C L Browne ◽  
A H Lockwood ◽  
J L Su ◽  
J A Beavo ◽  
A L Steiner
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinases ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Mitotic Spindle ◽  
Cyclic Nucleotide ◽  
Dependent Protein Kinase ◽  
Mitotic Apparatus ◽  
Dependent Protein

Cyclic nucleotides and cyclic nucleotide-dependent protein kinases have been implicated in the regulation of cell motility and division, processes that depend on the cell cytoskeleton. To determine whether cyclic nucleotides or their kinases are physically associated with the cytoskeleton during cell division, fluorescently labeled antibodies directed against cyclic AMP, cyclic GMP, and the cyclic nucleotide-dpendent protein kinases were used to localize these molecules in mitotic PtK1 cells. Both the cyclic GMP-dependent protein kinase and the type II regulatory subunit of the cyclic AMP-dependent protein kinase were localized on the mitotic spindle. Throughout mitosis, their distribution closely resembled that of tubulin. Antibodies to cyclic AMP, cyclic GMP, and the type I regulatory and catalytic subunits of the cyclic AMP-dependent protein kinase did not label the mitotic apparatus. The association between specific components of the cyclic neucleotide system and the mitotic spindle suggests that cyclic nucleotide-dependent phosphorylation of spindle proteins, such as those of microtubules, may play a fundamental role in the regulation of spindle assembly and chromosome motion.

Cyclic Nucleotides And PlateLet-Leukocyte Aggregates In Patients With Occlusive Arterial Disease

1981 ◽  
Author(s):  
B Kiersnowska-Rogowska ◽  
M Bielawiec ◽  
F Rogowski ◽  
A Bodzenta ◽  
J Giedrojć
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Cyclic Nucleotides ◽  
Arterial Disease ◽  
Lower Limbs ◽  
Control Group ◽  
Occlusive Arterial Disease ◽  
Hospital Deaths ◽  
And Function

The aim of the work was to study plasma cyclic nucleotides level /cyclic-AMP and cyclic-GMP/ and platelet-leukocyte aggregates in patients with obliterative arteriosclerosis of the lower limbs. The following parameters were investigated: cyclic-AMP and GMP radioimmunochemically by the use of a cyclic-AMP and cyclic-GMP assay kit, platelet leukocyte aggregates by the method of Silbergleit in our modification.The remainder were hospital deaths, five within the first 48 hours, 8 between 2-14 days, and 4 between 14 and 94 days. Five cases showed subendocardial infarction (SI). Four of these occuring out of hospital. The remaining 18 cases were transmural infarctions (TI). Sixteen of 17 hospital deaths exhibited TI.Significant decrease in cyclic-AMP level was found in arteriosclerotic patients in comparison to the control group. No significant changes in cyclic-GMP level were observed. The number of platelet-leukocyte aggregates was significantly higher in these patients.The influence of Hydroxy-ethyl-rutosides /HR/ on investigated parameters was also studie.The significant decrease in the level of cyclic-GMP in plasma was observed in patients after intravenously injection of 1000 mg of HR whereas no changes were found in cyclic-AMP level. The significant decrease in the number of platelet-leukocytes aggregates in the blood obtained after HR injection was also observed.Our results have shown the disturbances of plasma cyclic nucleotides balance and function of platelets and leukocyte in arteriosclerotic patients. This study also suggests that HR may be a modulating agent of these parameters.

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