Pharmacology of the Malpighian Tubules of Rhodnius and Carausius: The Structure-Activity Relationship of Tryptamine Analogues and the Role of Cyclic Amp

1971 ◽  
Vol 54 (3) ◽  
pp. 779-804 ◽  
Author(s):  
S.H. P. MADDRELL ◽  
D.E. M. PILCHER ◽  
B.O. C. GARDINER
Keyword(s):  
Cyclic Amp ◽  
Malpighian Tubule ◽  
Receptor Site ◽  
Adenosine Monophosphate ◽  
Malpighian Tubules ◽  
Stimulatory Action ◽  
Receptor Sites ◽  
Competitive Inhibitors ◽  
High Concentrations ◽  
Relationship Of

1. 5-Hydroxytryptamine (5-HT) and a few of its derivatives will cause an acceleration of secretion by the isolated Malpighian tubules of Rhodnius prolixus and Carausius morosus. Substitution in the terminal amino group of 5-HT causes little loss of effect, but changes in the indole ring and the hydroxy group in general abolish activity. 2. Most derivatives of 5-HT which do not stimulate secretion, and many other related amines, act as inhibitors of secretion in Rhodnius. This inhibition is probably of the competitive type. 3. Substances which stimulate secretion in Rhodnius are easily washed off the Malpighian tubules, although they will stimulate secretion at very low concentrations By contrast, competitive inhibitors wash away relatively slowly and inhibit only at much higher concentrations. It is suggested therefore that stimulation involves only momentary interactions between stimulant and receptor sites, but that competitive inhibitors spend considerably longer attached to the sites. 4. Cyclic 3',5'-adenosine monophosphate (cyclic AMP) will stimulate secretion by tubules of both Rhodnius and Carausius. Tubules of both species are very sensitive to cyclic AMP, measurable effects being produced at concentrations of 4 x 10-5 M/l in Rhodnius and 10-4 M/l in Carausius. 5. Aminophylline (theophylline ethylene diamine) at a concentration of 10-4 M/l stimulates secretion by Carausius tubules. This compound and other inhibitors of phosphodiesterase have no stimulatory action on Rhodnius tubules, but any such effect may be masked by the adverse reaction of the tubules to the high concentrations necessary. 6. Inhibitors of 5-HT action such as tryptamine and tyramine also inhibit secretion by Rhodnius Malpighian tubules induced by cyclic AMP. This may be due to a dependence of the action of cyclic AMP on the state of the diuretic hormone receptor site. 7. The evidence is consistent with the idea that 5-HT, other stimulant molecules related to 5-HT and the diuretic hormones interact with Malpighian tubule cells of Rhodnius and Carausius at specific sites, probably on the cell membrane facing the haemolymph. As a result of this, secretion is induced, possibly through the action of intracellular cyclic AMP produced as a response.

scholarly journals A comparison of the effects of two putative diuretic hormones from Locusta migratoria on isolated locust malpighian tubules

1993 ◽  
Vol 175 (1) ◽  
pp. 1-14 ◽  
Author(s):  
G. M. Coast ◽  
R. C. Rayne ◽  
T. K. Hayes ◽  
A. I. Mallet ◽  
K. S. Thompson ◽  
...  
Keyword(s):  
Cyclic Amp ◽  
Arginine Vasopressin ◽  
Locusta Migratoria ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Enzymatic Digestion ◽  
Malpighian Tubules ◽  
Suboesophageal Ganglion ◽  
Anatomy And Physiology ◽  
Strong Stimulation

Previous work has shown that a peptide related to arginine vasopressin is present in the suboesophageal ganglion of the locust, Locusta migratoria. This peptide was determined to be an anti-parallel dimer of the nonapeptide Cys-Leu-Ile-Thr-Asn-Cys-Pro-Arg-Gly-NH2 and was reported to stimulate cyclic AMP production and fluid secretion in a combined Malpighian tubules and midgut preparation from locusts. For these reasons the peptide has been called the arginine-vasopressin-like insect diuretic hormone (AVP-like IDH). Recently, a second diuretic peptide (Locusta-DP), which is related to corticotropin releasing factor, has been identified: this is a potent stimulant of fluid secretion and cyclic AMP production by isolated locust tubules. Because water balance in insects is likely to be controlled by a cocktail of hormones acting on both Malpighian tubules and hindgut, this study directly compares the activity of these two peptides in fluid secretion and cyclic AMP production bioassays on one target organ, the isolated Malpighian tubule of Locusta migratoria. Locusta-DP was synthesised directly, whereas the dimeric AVP-like IDH was obtained by oxidation of a synthetic nonapeptide monomer. Products were separated by RP-HPLC and their structures unequivocally confirmed by enzymatic digestion, sequence analysis and electrospray mass spectrometry. We show that Locusta-DP causes strong stimulation of fluid secretion and cyclic AMP production, whereas the AVP-like IDH has no effect in either assay. These findings are discussed in the light of recent work on the anatomy and physiology of the vasopressin-like immunoreactive (VPLI) neurones in the suboesophageal ganglion of Locusta migratoria, the proposed source of the AVP-like peptide.

scholarly journals The distribution of a CRF-like diuretic peptide in the blood-feeding bug Rhodnius prolixus

1999 ◽  
Vol 202 (15) ◽  
pp. 2017-2027 ◽  
Author(s):  
V.A. Te Brugge ◽  
S.M. Miksys ◽  
G.M. Coast ◽  
D.A. Schooley ◽  
I. Orchard
Keyword(s):  
Cyclic Amp ◽  
Malpighian Tubule ◽  
Immunogold Labelling ◽  
Blood Feeding ◽  
Neurosecretory Cells ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Double Labelling ◽  
Neurohaemal Areas ◽  
The Brain

The blood-feeding bug Rhodnius prolixus ingests a large blood meal, and this is followed by a rapid diuresis to eliminate excess water and salt. Previous studies have demonstrated that serotonin and an unidentified peptide act as diuretic factors. In other insects, members of the corticotropin-releasing factor (CRF)-related peptide family have been shown to play a role in post-feeding diuresis. Using fluorescence immunohistochemistry and immunogold labelling with antibodies to the Locusta CRF-like diuretic hormone (Locusta-DH) and serotonin, we have mapped the distribution of neurones displaying these phenotypes in R. prolixus. Strong Locusta-DH-like immunoreactivity was found in numerous neurones of the central nervous system (CNS) and, in particular, in medial neurosecretory cells of the brain and in posterior lateral neurosecretory cells of the mesothoracic ganglionic mass (MTGM). Positively stained neurohaemal areas were found associated with the corpus cardiacum (CC) and on abdominal nerves 1 and 2. In addition, Locusta-DH-like immunoreactive nerve processes were found over the posterior midgut and hindgut. Double-labelling studies for Locusta-DH-like and serotonin-like immunoreactivity demonstrated some co-localisation in the CNS; however, no co-localisation was found in the medial neurosecretory cells of the brain, the posterior lateral neurosecretory cells of the MTGM or neurohaemal areas. To confirm the presence of a diuretic factor in the CC and abdominal nerves, extracts were tested in Malpighian tubule secretion assays and cyclic AMP assays. Extracts of the CC and abdominal nerves caused an increase in the rate of secretion and an increase in the level of cyclic AMP in the Malpighian tubules of fifth-instar R. prolixus. The presence of the peptide in neurohaemal terminals of the CC and abdominal nerves that are distinct from serotonin-containing terminals indicates that the peptide is capable of being released into the haemolymph and that this release can be independent of the release of serotonin.

A Malpighian Tubule Lime Gland in an Insect Inhabiting Alkaline Salt Lakes

1989 ◽  
Vol 145 (1) ◽  
pp. 63-78 ◽  
Author(s):  
DAVID B. HERBST ◽  
TIMOTHY J. BRADLEY
Keyword(s):  
Malpighian Tubule ◽  
Cell Types ◽  
Chemical Precipitation ◽  
Malpighian Tubules ◽  
Salt Lakes ◽  
Alkaline Salt ◽  
X Ray ◽  
Posterior Pair ◽  
High Concentrations ◽  
Scanning Electron

The alkali fly, Ephydra hians Say, inhabits alkaline salt lakes which can contain concentrations of dissolved carbonate and bicarbonate as high as 500 mmol l−1. Larvae of the alkali fly possess two pairs of Malpighian tubules. The posterior pair has a morphology similar to that of the tubules of most other insects, but the anterior pair is modified into an enlarged gland containing white microsphere concretions. We describe the ultrastructure of all cell types in both pairs of tubules. Using scanning electron microscope (SEM) X-ray microanalysis and chemical CO2 quantification, we demonstrate that the concretions in the lime glands are composed of nearly pure calcium carbonate. Isolated preparations of lime gland tubules accumulate 45Ca significantly more rapidly than do normal tubules. Although similar to the rime concretions found in the Malpighian tubules of other Diptera, the lime glands of this insect may function to regulate the high concentrations of carbonate and bicarbonate encountered in their aquatic environment. It is proposed that the mechanism of this regulation may be chemical precipitation of carbonate/bicarbonate with calcium in the lumen of these specialized lime gland tubules.

scholarly journals The insulin-stimulated cyclic AMP phosphodiesterase binds to a single class of protein sites on the liver plasma membrane

1981 ◽  
Vol 198 (3) ◽  
pp. 703-706 ◽  
Author(s):  
M D Houslay ◽  
R J Marchmont
Keyword(s):  
Plasma Membrane ◽  
Cyclic Amp ◽  
Plasma Membranes ◽  
Receptor Site ◽  
Single Class ◽  
Liver Plasma Membrane ◽  
Cyclic Amp Phosphodiesterase ◽  
Receptor Sites ◽  
Rat Liver Plasma Membranes ◽  
Dependent Protein

The peripheral cycle AMP phosphodiesterase from rat liver plasma membranes binds with high affinity (2.4 nM) to a single class of receptor sites on the liver plasma membrane. These receptor sites appear to be proteins, as they are trypsin- and heat-labile. The sensitivity of these sites to denaturation by trypsin and heat is a first-order process. The presence of Ca2+ (5 mM) increases the affinity of these sites for the enzyme, but does not alter their total number. The receptor sites and the cyclic AMP phosphodiesterase occur in similar numbers, at around 2 pmol/mg of plasma-membrane protein. It is proposed that the peripheral, liver plasma-membrane cyclic AMP phosphodiesterase is attached to a specific site on the insulin receptor and that the binding of insulin to the receptor site triggers a conformational change in the enzyme such that the enzyme can be phosphorylated and activated by an endogenous cyclic AMP-dependent protein kinase.

scholarly journals ION AND FLUID SECRETION BY DIFFERENT SEGMENTS OF THE MALPIGHIAN TUBULES OF THE BLACK FIELD CRICKET TELEOGRYLLUS OCEANICUS

1993 ◽  
Vol 177 (1) ◽  
pp. 1-22
Author(s):  
A. T. Marshall ◽  
P. Cooper ◽  
G. D. Rippon ◽  
A. E. Patak
Keyword(s):  
Cyclic Amp ◽  
Fluid Secretion ◽  
Distal Segment ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Osmotic Concentration ◽  
Corpora Cardiaca ◽  
Diuretic Hormone ◽  
High Concentrations ◽  
Tubule Fluid

Cricket Malpighian tubules have two morphologically distinct segments, a thin distal segment, which occupies approximately 10 % of the total tubule length, and a main segment. The two segments differ in secretion rates and response to corpora cardiaca extract. The secreted fluids differ in osmotic concentration and elemental composition. The distal segment secretes fluid at a rate (per mm length) which is approximately twice that of the main segment under control conditions. After stimulation by corpora cardiaca extract (Cc) the rate from the main segment approximately doubles whilst the distal segment rate remains unchanged. Fluid from the main segment and the whole tubule is slightly hypo-osmotic to the medium (5–11 mosmol kg-1) under control conditions, whereas that from the distal segment is slightly hyperosmotic (12 mosmol kg-1). On stimulation with Cc, the whole tubule fluid becomes slightly hyperosmotic (12 mosmol kg-1), that from the main segment remains slightly hypo-osmotic (3 mosmol kg-1) but fluid from the distal segment becomes very hyperosmotic (55 mosmol kg-1). Differences between the tubule fluid and the medium osmolality are indicated in parentheses. Fluid from the main segment has high concentrations of K (166 mmol l-1), Cl (111 mmol l-1), Na (41 mmol l-1) and P (83 mmol l-1), whereas that from the distal segment has high concentrations of K (101 mmol l-1) and Cl (137 mmol l-1). On stimulation with Cc, the elemental concentrations in fluids from the main segments and whole tubules do not change significantly but the K and Cl concentrations in distal segment fluid increase (182 and 188 mmol l-1 respectively). The Mg present in whole tubule fluid is derived largely from the distal segment. The ionic composition accounts for the observed osmotic concentrations in fluid from whole tubules, main segments and stimulated distal segments, but not for the concentrations in fluid from unstimulated distal segments. The fluid from unstimulated distal segments contains an unidentified organic solute accounting for approximately 90 mosmol kg-1 of the osmotic concentration. The distal segment contributes 22 % and 11 % of the fluid volume, 26 % Cl, 14 % K and 12 % Cl, 11 % K in control and Cc-stimulated tubules respectively. Considerably higher values are observed in individual tubules. The distal segment makes a significant contribution to the total ion output of the tubule. The cyclic AMP content of tubule segments treated with corpora cardiaca extract was found to increase in both main and distal segments. When expressed in terms of protein content there was no difference between segments. However, in terms of total cell volume, the cells of the distal segment had a tenfold greater cyclic AMP content than those of the main segment. This is consistent with a 10- to 20-fold higher secretion rate of K by the distal segment. It is suggested that the distal segment, whilst having a higher length-specific fluid secretion rate than the main segment, is, nevertheless, concerned primarily with ion and solute secretion since it is unresponsive to diuretic hormone. The prime role of the main segment, which does respond to diuretic hormone, is fluid secretion. There appear to be major differences in hydraulic conductivity between the two segments.

scholarly journals Leucokinin increases paracellular permeability in insect Malpighian tubules

1996 ◽  
Vol 199 (11) ◽  
pp. 2537-2542 ◽  
Author(s):  
S Wang ◽  
A Rubenfeld ◽  
T Hayes ◽  
K Beyenbach
Keyword(s):  
Cyclic Amp ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Paracellular Pathway ◽  
Chloride Permeability ◽  
Transport Pathways ◽  
Transcellular Transport ◽  
Electrophysiological Studies

There are two major transport pathways across epithelia: a transcellular pathway through cells and a paracellular pathway between cells. Previous electrophysiological studies in mosquito Malpighian tubules suggested that the neuropeptide leucokinin-VIII (LK-VIII) increases the chloride permeability of the paracellular pathway. To test the effect of LK-VIII on the paracellular pathway further, we measured transepithelial permeabilities of inulin and sucrose in isolated Malpighian tubules from the mosquito Aedes aegypti. Cell membranes are impermeable to inulin and sucrose, leaving the paracellular pathway as the only route for their transepithelial permeation. LK-VIII (10(-6) mol l-1) significantly increased transepithelial permeability to both inulin (by 73.8 %) and sucrose (by 32.4 %) in parallel with a significant increase in rates of transepithelial fluid secretion (by 75­90 %). Cyclic adenosine monophosphate (cyclic AMP, 10(-4) mol l-1), which is known to stimulate transcellular transport, also increased rates of transepithelial fluid secretion (by 57­59 %), but it did so without increasing the permeability to sucrose and inulin. Thus, LK-VIII increases the permeability of the paracellular pathway whereas cyclic AMP does not.

scholarly journals Electrical transients in the cell-volume response to cyclic AMP of the tsetse fly Malpighian tubule

1996 ◽  
Vol 199 (7) ◽  
pp. 1597-1604
Author(s):  
L Isaacson ◽  
S Nicolson
Keyword(s):  
Cyclic Amp ◽  
Cell Volume ◽  
Malpighian Tubule ◽  
Tsetse Fly ◽  
Malpighian Tubules ◽  
Transepithelial Transport ◽  
Specific Cell ◽  
Shunt Resistance ◽  
Cable Properties ◽  
Subsequent Decrease

1. Using cyclic AMP to stimulate perfused tsetse fly Malpighian tubules bathed in SO42- Ringer frequently causes an immediate but transient peak in transtubular potential (Vt), before stabilisation of Vt at an increased value. 2. These transients were investigated by monitoring the associated changes in cable properties and current­voltage (I/V) relationships. Tubules were perfused and bathed in either Cl- Ringer or SO42- Ringer (containing 8 mmol l-1 Cl-). 3. Tubules bathed in Cl- Ringer showed a transient swelling of the cells on exposure to cyclic AMP. Cable analysis confirmed the visually observed narrowing of the tubular lumen and revealed transient increases in core resistance (Rc) and transtubular resistance (Rt). As the cells returned to their initial volume, the lumen became distended, and Rc and Rt fell below their initial levels. These changes were accompanied by an increase, and a subsequent decrease, in the slope of the I/V plot. 4. None of the above changes was apparent in SO42- Ringer, other than a fall in Rt and in the slope of the I/V plot. 5. The results suggest that, in Cl- Ringer, cyclic AMP induces swelling of the tubular cells by promoting increased basolateral solute (and water) entry and that the subsequent rapid return to normal cell volume, with a concomitant progressive increase in the rate of tubular secretion, reflects the operation of a specific cell-volume regulatory mechanism of transepithelial transport. 6. The cyclic-AMP-induced peak that occurs in Vt in SO42- Ringer appears to be primarily due to a transient overshoot in the fall in series resistance (i.e. an increase in basolateral Na+ conductance), accompanied by a proportionately lesser increase in shunt resistance.

Fine Structure of the Malpighian Tubules of the Mosquito, Culex pipiens

1971 ◽  
Vol 29 ◽  
pp. 402-403
Author(s):  
Brendan Clifford
Keyword(s):  
Fine Structure ◽  
Culex Pipiens ◽  
Stellate Cell ◽  
Malpighian Tubule ◽  
Cell Types ◽  
Instar Larva ◽  
Malpighian Tubules ◽  
Calliphora Erythrocephala ◽  
Distinct Cell ◽  
Basal Plasma

An ultrastructural investigation of the Malpighian tubules of the fourth instar larva of Culex pipiens was undertaken as part of a continuing study of the fine structure of transport epithelia.Each of the five Malpighian tubules was found to be morphologically identical and regionally undifferentiated. Two distinct cell types, the primary and stellate, were found intermingled along the length of each tubule. The ultrastructure of the stellate cell was previously described in the Malpighian tubule of the blowfly, Calliphora erythrocephala by Berridge and Oschman.The basal plasma membrane of the primary cell is extremely irregular, giving rise to a complex interconnecting network of basal channels. The compartments of cytoplasm entrapped within this system of basal infoldings contain mitochondria, free ribosomes, and small amounts of rough endoplasmic reticulum. The mitochondria are distinctive in that the cristae run parallel to the long axis of the organelle.

Elucidating cyclic AMP signaling in subcellular domains with optogenetic tools and fluorescent biosensors

2019 ◽  
Vol 47 (6) ◽  
pp. 1733-1747 ◽  
Author(s):  
Christina Klausen ◽  
Fabian Kaiser ◽  
Birthe Stüven ◽  
Jan N. Hansen ◽  
Dagmar Wachten
Keyword(s):  
Cyclic Amp ◽  
Adenosine Monophosphate ◽  
Adenylyl Cyclases ◽  
Temporal Precision ◽  
Fluorescent Biosensors ◽  
Subcellular Domains ◽  
Spatio Temporal ◽  
Hydrolysis Of ◽  
Shed Light ◽  
Cyclic Amp Signaling

The second messenger 3′,5′-cyclic nucleoside adenosine monophosphate (cAMP) plays a key role in signal transduction across prokaryotes and eukaryotes. Cyclic AMP signaling is compartmentalized into microdomains to fulfil specific functions. To define the function of cAMP within these microdomains, signaling needs to be analyzed with spatio-temporal precision. To this end, optogenetic approaches and genetically encoded fluorescent biosensors are particularly well suited. Synthesis and hydrolysis of cAMP can be directly manipulated by photoactivated adenylyl cyclases (PACs) and light-regulated phosphodiesterases (PDEs), respectively. In addition, many biosensors have been designed to spatially and temporarily resolve cAMP dynamics in the cell. This review provides an overview about optogenetic tools and biosensors to shed light on the subcellular organization of cAMP signaling.

In Vitro Effects of Ethanol on Rabbit Platelet Aggregation, Secretion of Granule Contents, and Cyclic AMP Levels in the Presence of Prostacyclin

1989 ◽  
Vol 61 (02) ◽  
pp. 254-258 ◽  
Author(s):  
Margaret L Rand ◽  
Peter L Gross ◽  
Donna M Jakowec ◽  
Marian A Packham ◽  
J Fraser Mustard
Keyword(s):  
Cyclic Amp ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Inhibitory Effects ◽  
Low Concentrations ◽  
Rabbit Platelets ◽  
High Concentrations ◽  
In Vitro Effects ◽  
Aggregation Of Platelets

SummaryEthanol, at physiologically tolerable concentrations, inhibits platelet responses to low concentrations of collagen or thrombin, but does not inhibit responses of washed rabbit platelets stimulated with high concentrations of ADP, collagen, or thrombin. However, when platelet responses to high concentrations of collagen or thrombin had been partially inhibited by prostacyclin (PGI2), ethanol had additional inhibitory effects on aggregation and secretion. These effects were also observed with aspirin- treated platelets stimulated with thrombin. Ethanol had no further inhibitory effect on aggregation of platelets stimulated with ADP, or the combination of ADP and epinephrine. Thus, the inhibitory effects of ethanol on platelet responses in the presence of PGI2 were very similar to its inhibitory effects in the absence of PGI2, when platelets were stimulated with lower concentrations of collagen or thrombin. Ethanol did not appear to exert its inhibitory effects by increasing cyclic AMP above basal levels and the additional inhibitory effects of ethanol in the presence of PGI2 did not appear to be brought about by further increases in platelet cyclic AMP levels.

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