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.

THE EFFECTS OF MANDUCA SEXTA DIURETIC HORMONE ON FLUID TRANSPORT BY THE MALPIGHIAN TUBULES AND CRYPTONEPHRIC COMPLEX OF MANDUCA SEXTA

1993 ◽  
Vol 178 (1) ◽  
pp. 231-243 ◽  
Author(s):  
N. Audsley ◽  
G. M. Coast ◽  
D. A. Schooley
Keyword(s):  
Cyclic Amp ◽  
Manduca Sexta ◽  
Fluid Transport ◽  
Basal Membrane ◽  
Fluid Secretion ◽  
Hormonal Control ◽  
Malpighian Tubules ◽  
Proximal Tubules ◽  
Fluid Absorption ◽  
Diuretic Hormone

1. Manduca sexta diuretic hormone (Mas-DH) stimulates fluid secretion by adult Malpighian tubules of M. sexta, demonstrating its site of diuretic action in M. sexta for the first time. It was not possible to develop a suitable bioassay to measure fluid secretion in larval proximal tubules. 2. Mas-DH has an antidiuretic action on the cryptonephric complex of larval M. sexta because it increases fluid absorption from the rectum. It appears that in this complex Mas-DH is acting on a Na+/K+/2Cl- co-transporter, presumably on the basal membrane of the cryptonephric Malpighian tubules, because Mas-DH-stimulated fluid absorption by the cryptonephric complex is inhibited by bumetanide or the removal of Cl-, Na+ or K+ from the haemolymph side of the tissue. This is the first demonstration of hormonal control of fluid absorption by the cryptonephric complex. 3. Concomitant with the stimulation of fluid transport, Mas-DH increases the amount of cyclic AMP secreted by adult Malpighian tubules and the cryptonephric complex. In addition, Mas-DH promotes cyclic AMP production by the larval proximal tubules.

Insect-Like Characteristics of the Malpighian Tubules of a Non-Insect: Fluid Secretion in the Centipede Uthobius Forficatus (Myriapoda: Chilopoda)

1991 ◽  
Vol 158 (1) ◽  
pp. 165-180
Author(s):  
ANGELA WENNING ◽  
U. T. E. GREISINGER ◽  
JACQUES P. PROUX
Keyword(s):  
Cyclic Amp ◽  
Flow Rate ◽  
Fluid Secretion ◽  
Urine Flow ◽  
Malpighian Tubules ◽  
Urine Flow Rate ◽  
Dibutyryl Cyclic Amp ◽  
Diuretic Hormone ◽  
Urine Formation ◽  
Lithobius Forficatus

Fluid secretion by isolated upper and lower portions of Malpighian tubules in the centipede Lithobius forficatus L. was studied. Ion requirements, cellular and transepithelial potentials, dependence on external osmolality and the effects of an insect diuretic factor and transport-active drugs were investigated. Unlike many insects, L. forficatus exhibited strongly Na+-dependent, K+-independent urine formation. However, as in many insects, upper and lower tubule portions from L. forficatus produced a K+-enriched, hypertonic fluid, and the transepithelial potential was positive with respect to the haemolymph. Furthermore, furosemide (5×10−4moll−1) reversibly inhibited urine formation. Ouabain, even at 10−3moll−1, had little effect on urine flow rate in upper tubules but inhibited secretion in lower tubules, albeit not completely. Locust diuretic hormone (at 10−7moll−1) enhanced fluid secretion in L. forficatus, but its action was not mimicked by dibutyryl cyclic AMP. The results suggest that some characteristics attributed exclusively to insects are common to non-insect arthropods.

scholarly journals 5-Hydroxytryptamine: a second diuretic hormone in Rhodnius prolixus

1991 ◽  
Vol 156 (1) ◽  
pp. 557-566 ◽  
Author(s):  
S. H. Maddrell ◽  
W. S. Herman ◽  
R. L. Mooney ◽  
J. A. Overton
Keyword(s):  
Salivary Glands ◽  
Malpighian Tubule ◽  
Peptide Hormone ◽  
Fluid Secretion ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Biologically Active ◽  
Diuretic Hormone ◽  
Naturally Occurring ◽  
Tubule Fluid

Bioassays of 5-hydroxytryptamine (5-HT) in fifth-instar Rhodnius prolixus haemolymph using Calliphora salivary glands indicate that: (1) biologically active 5-HT is present, (2) in unfed animals there is not enough 5-HT to stimulate Malpighian tubule fluid secretion, and (3) there is enough 5-HT soon after the initiation of feeding to stimulate rapid tubule secretion. The 5-HT receptor antagonists ketanserin and spiperone reversibly and selectively inhibit 5-HT-induced fluid secretion, indicating the presence of specific 5-HT receptors on Rhodnius Malpighian tubules. The data provide evidence that 5-HT is a naturally occurring hormone acting with a previously described peptide hormone to regulate diuresis in this species.

Anti-diuresis in the blood-feeding insect Rhodnius prolixus Stål: the peptide CAP2b and cyclic GMP inhibit Malpighian tubule fluid secretion.

1997 ◽  
Vol 200 (17) ◽  
pp. 2363-2367 ◽  
Author(s):  
M C Quinlan ◽  
N J Tublitz ◽  
M J O'Donnell
Keyword(s):  
Cyclic Gmp ◽  
Physiological Role ◽  
Malpighian Tubule ◽  
Fluid Secretion ◽  
Blood Feeding ◽  
Rhodnius Prolixus ◽  
Malpighian Tubules ◽  
Tubule Fluid ◽  
Secretion Rates

Rhodnius prolixus eliminates NaCl-rich urine at high rates following its infrequent but massive blood meals. This diuresis involves stimulation of Malpighian tubule fluid secretion by diuretic hormones released in response to distention of the abdomen during feeding. The precipitous decline in urine flow that occurs several hours after feeding has been thought until now to result from a decline in diuretic hormone release. We suggest here that insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP are part of a novel mechanism of anti-diuresis. Secretion rates of 5-hydroxytryptamine-stimulated Malpighian tubules are reduced by low doses of CAP2b or cyclic GMP. Maximal secretion rates are restored by exposing tubules to 1 mmol l-1 cyclic AMP. Levels of cyclic GMP in isolated tubules increase in response to CAP2b, consistent with a role for cyclic GMP as an intracellular second messenger. Levels of cyclic GMP in tubules also increase as urine output rates decline in vivo, suggesting a physiological role for this nucleotide in the termination of diuresis.

Hormonal Control of the Malpighian Tubules of the Stick Insect, Carausius Morosus

1970 ◽  
Vol 52 (3) ◽  
pp. 653-665 ◽  
Author(s):  
DIANA E. M. PILCHER
Keyword(s):  
Stick Insect ◽  
Hormonal Control ◽  
The State ◽  
Malpighian Tubules ◽  
Suboesophageal Ganglion ◽  
Carausius Morosus ◽  
Corpora Cardiaca ◽  
Diuretic Hormone ◽  
The Brain

1. Urine secretion by isolated Malpighian tubules of Carausius is accelerated by a diuretic hormone which can be extracted from the brain, corpora cardiaca and suboesophageal ganglion. 2. The level of this hormone in the haemolymph varies according to the state of hydration of the insect. 3. The hormone is inactivated by the tubules, and a mechanism is proposed whereby the tubules might be controlled by the hormone in vivo.

The initial stages in the action of an insecticidal delta-endotoxin of Bacillus thuringiensis var. israelensis on the epithelial cells of the malpighian tubules of the insect, Rhodnius prolixus

1988 ◽  
Vol 90 (1) ◽  
pp. 131-144
Author(s):  
S.H. Maddrell ◽  
N.J. Lane ◽  
J.B. Harrison ◽  
J.A. Overton ◽  
R.B. Moreton
Keyword(s):  
Bacillus Thuringiensis ◽  
Intercellular Junctions ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Ultrastructural Changes ◽  
Cytoplasmic Vacuolization ◽  
Large Numbers ◽  
Delta Endotoxin ◽  
High Concentrations ◽  
Very High

The effects of the 27 X 10(3) Mr insecticidal delta-endotoxin from Bacillus thuringiensis var. israelensis have been studied using, as a model system, isolated insect Malpighian tubules. At all concentrations of the toxin higher than 1 microgram ml-1 (4 X 10(−8) moll-1) applied to the outer surface of the tubules, fluid secretion failed within about 30 min. Except at very high concentrations, where failure always takes at least 30 s, there was an inverse relationship between the concentration of toxin and the time of failure of toxin-treated tubules. During exposure to toxin, the tubules were initially unaffected for a relatively long period and then rapid failure occurred. If the tubules were removed into toxin-free saline just before failure would have occurred, fluid secretion remained normal for at least 2 h, but on return to the origin toxin-containing saline failure was almost immediate. The toxin was found not to bind to the basement membrane. Ultrastructural changes became evident as tubule failure occurred. These initially involved modifications to the basal side of the cells, but later also to the luminal microvilli. Intercellular junctions became disassociated and cytoplasmic vacuolization occurred. The population of intramembranous particles in the basal membranes became reduced with time. Our findings suggest the following hypothesis for the initial stages in the interaction of the toxin with the tubules. Toxin molecules attach to the accessible cell membranes progressively and irreversibly. They do not readily associate by diffusing laterally in the membrane, so that toxic effects develop only when sufficiently large numbers of them attach close together. The molecules may then associate in some way as a complex, perhaps forming a pore in the membrane. Relatively few such pores lead rapidly to cell failure and death.

CAP2b, a cardioacceleratory peptide, is present in Drosophila and stimulates tubule fluid secretion via cGMP

1995 ◽  
Vol 269 (6) ◽  
pp. R1321-R1326 ◽  
Author(s):  
S. A. Davies ◽  
G. R. Huesmann ◽  
S. H. Maddrell ◽  
M. J. O'Donnell ◽  
N. J. Skaer ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Manduca Sexta ◽  
High Performance ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Cyclic Monophosphate ◽  
Cgmp Signaling ◽  
Camp And Cgmp ◽  
Tubule Fluid ◽  
Stimulation Of

A cardioacceleratory peptide, CAP2b, identified originally in the lepidopteran Manduca sexta, stimulates fluid secretion by Malpighian tubules of the dipteran Drosophila melanogaster. High-performance liquid chromatography analyses of adult D. melanogaster reveal the presence of a CAP2b-like peptide, that coelutes with M. sexta CAP2b and synthetic CAP2b and that has CAP2b-like effects on the M. sexta heart. CAP2b accelerates fluid secretion in tubules stimulated by adenosine 3',5'-cyclic monophosphate (cAMP) but has no effect on tubules stimulated by guanosine 3',5'-cyclic monophosphate (cGMP), implying that it acts through the latter pathway. By contrast, the action of leucokinin is additive to both cAMP and cGMP but not to thapsigargin, suggesting that leucokinin acts by the elevation of intracellular calcium. CAP2b stimulation elevates tubule cGMP levels but not those of cAMP. By contrast, leucokinin has no effect on levels of either cyclic nucleotide. Both CAP2b and cGMP increase transepithelial potential difference, suggesting that stimulation of vacuolar-adenosinetriphosphatase action underlies the corresponding increases in fluid secretion. Overall, the results show that a Drosophila CAP2b-related peptide acts to stimulate fluid secretion by Malpighian tubules through the cGMP-signaling pathway.

scholarly journals Characterization of a set of abdominal neuroendocrine cells that regulate stress physiology using colocalized diuretic peptides in Drosophila

2017 ◽  
Author(s):  
Meet Zandawala ◽  
Richard Marley ◽  
Shireen A. Davies ◽  
Dick R. Nässel
Keyword(s):  
Stress Responses ◽  
Water Retention ◽  
Fluid Secretion ◽  
Cell Types ◽  
Neurosecretory Cells ◽  
Malpighian Tubules ◽  
Neuroendocrine Cells ◽  
Signaling Systems ◽  
Diuretic Hormone ◽  
Functional Relations

AbstractMultiple neuropeptides are known to regulate water and ion balance in Drosophila melanogaster. Several of these peptides also have other functions in physiology and behavior. Examples are corticotropin-releasing factor-like diuretic hormone (diuretic hormone 44; DH44) and leucokinin (LK), both of which induce fluid secretion by Malpighian tubules (MTs), but also regulate stress responses, feeding, circadian activity and other behaviors. Here, we investigated the functional relations between the LK and DH44 signaling systems. DH44 and LK peptides are only colocalized in a set of abdominal neurosecretory cells (ABLKs). Targeted knockdown of each of these peptides in ABLKs leads to increased resistance to desiccation, starvation and ionic stress. Food ingestion is diminished by knockdown of DH44, but not LK, and water retention is increased by LK knockdown only. Thus, the two colocalized peptides display similar systemic actions, but differ with respect to regulation of feeding and body water retention. We also demonstrated that DH44 and LK have additive effects on fluid secretion by MTs. It is likely that the colocalized peptides are coreleased from ABLKs into the circulation and act on the tubules where they target different cell types and signaling systems to regulate diuresis and stress tolerance. Additional targets seem to be specific for each of the two peptides and subserve regulation of feeding and water retention. Our data suggest that the ABLKs and hormonal actions are sufficient for many of the known DH44 and LK functions, and that the remaining neurons in the CNS play other functional roles.

scholarly journals Excretion in the House Cricket (Acheta Domesticus): Stimulation of Diuresis by Tissue Homogenates

1987 ◽  
Vol 129 (1) ◽  
pp. 63-81 ◽  
Author(s):  
JEFFREY H. SPRING ◽  
SHELIA R. HAZELTON
Keyword(s):  
Lethal Dose ◽  
Fluid Secretion ◽  
Sodium Concentration ◽  
Inhibitory Effect ◽  
Acheta Domesticus ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Tissue Homogenates ◽  
Extreme Sensitivity

1. A new method is described for maintaining cricket Malpighian tubules in vitro. Warmed, oxygenated saline is circulated rapidly past the tubules, while the secreted urine is collected under oil for analysis. This technique allows the cricket tubules to be observed and manipulated for extended periods (6 h), in contrast to their short life (>1 h) using conventional methods. 2. Cricket tubules show extreme sensitivity to oxygen deprivation, such that 15 min of anoxia represents the median lethal dose (LD50) for in vitro preparations. 3. Homogenates of corpus cardiacum (CC) cause the rate of fluid secretion by the tubules to double. The maximum stimulation is dose-dependent over the range 0.01 to 1.0 CC. Homogenates of brain and other ganglia show much smaller stimulatory effects (0.01-0.02 CC-equivalents). Cyclic AMP mimics the increase in secretion rate, but has an inhibitory effect on the smooth muscle of the ureter. 4. Control preparations maintain a urine osmotic pressure (OP) that is hyperosmotic to the bath by 5–10 mosmol l−1. CC homogenate produces a decrease in urine OP to 10–12 mosmol l−1 hypo-osmotic to the bath. This suggests that active solute reabsorption is occurring in the lower tubule or ampulla. 5. Stimulation by CC homogenate increases the urine potassium concentration slightly less than two-fold, whereas the sodium concentration increases by a maximum of five-fold and remains at a higher concentration than potassium throughout the experiment. Tubule secretion rate is drastically inhibited in nominally sodium-free saline.

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