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 SYNERGISM OF HORMONES CONTROLLING EPITHELIAL FLUID TRANSPORT IN AN INSECT

1993 ◽  
Vol 174 (1) ◽  
pp. 65-80 ◽  
Author(s):  
S. H. P. Maddrell ◽  
W. S. Herman ◽  
J. A. Farndale ◽  
J A Riegel
Keyword(s):  
Adenylate Cyclase ◽  
Fluid Transport ◽  
Fluid Secretion ◽  
Rapid Onset ◽  
Threshold Concentration ◽  
Malpighian Tubules ◽  
Dependent Manner ◽  
Response Curves ◽  
Diuretic Hormone ◽  
Dose Dependent

Forskolin stimulates rapid fluid secretion by the Malpighian tubules of Rhodnius prolixus at concentrations above 5x10–6 mol l-1. In the presence of a threshold concentration of forskolin, the tubules are 30–50 times more sensitive to 5-hydroxytryptamine (5-HT) than in its absence. Similar synergism is seen between 5-HT and extracts of the mesothoracic ganglionic mass (which is rich in the peptide diuretic hormone, DH) and between 5-HT and samples of haemolymph, also rich in peptide DH, from fed insects 1–2 h after feeding. The dose-response curves for mixtures of forskolin and 5-HT and of peptide DH and 5-HT are all very steep, approximately five times steeper than for any one stimulant alone. Forskolin, 5-HT and extracts of the ganglionic mass all stimulated adenylate cyclase from broken membrane preparations from the Malpighian tubules in a dose-dependent manner and at doses similar to those required to stimulate fluid secretion by intact tubules. Mixtures of ganglionic extract and 5- HT stimulated adenylate cyclase activity in a synergistic fashion. Injections into fifth-instar Rhodnius, 24 h before feeding, of 5,7-dihydroxytryptamine, which is known to block or reduce 5-HT release, caused delays in the onset of the consequent diuresis or prevented it altogether. This is consistent with the proposal that the rapid onset of diuresis after feeding is caused by the simultaneous release of 5-HT and peptide DH acting synergistically.

scholarly journals Effect of Manduca Sexta Diuretic Hormone and related Peptides on isolated Malpigfflan Tubules of the House Cricket Acheta Domesticus (L.)

1992 ◽  
Vol 162 (1) ◽  
pp. 331-338
Author(s):  
GEOFFREY M. COAST ◽  
TIMOTHY K. HAYES ◽  
IAIN KAY ◽  
JUM-SOOK CHUNG
Keyword(s):  
Cyclic Amp ◽  
Manduca Sexta ◽  
Pieris Rapae ◽  
Fluid Secretion ◽  
Acheta Domesticus ◽  
Malpighian Tubules ◽  
In Vivo Studies ◽  
Methionine Residues

Previously, a corticotropin releasing factor (CRF)-like diuretic peptide (Manduca-DH) has been isolated from Manduca sexta and shown to stimulate fluid excretion in vivo in post-eclosion Pieris rapae adults and in pre-wandering postfeeding Manduca sexta larvae. However, Manduca- DH was reported to have no effect on Malpighian tubules in vitro. Manduca-DH and [Nle2,11]-Manduca-DH were synthesized in Texas and assayed in London on isolated Malpighian tubules of Acheta domesticus. Manduca- DH stimulated fluid secretion by about 60% of the maximum response achievable with extracts of corpora cardiaca and increased the production of cyclic AMP. In combination with 10−4 mol l−1 3-isobutyl-l-methyl xanthine (IBMX), Manduca-DH stimulated maximal secretion. A number of CRF-related peptides also stimulated fluid secretion and cyclic AMP production in cricket tubules, and the CRF antagonist α-helical-CRF[9-14] blocked the stimulation of fluid secretion by Manduca-DH. [Nle2,11]-Manduca-DH was more active than Manduca-DH in both assays, suggesting that methionine residues in the natural peptide may become oxidized. Taken in conjunction with previous in vivo studies, the present findings suggest that a Manduca-DH-Mke diuretic peptide is the hormone controlling post-eclosion diuresis in butterflies, and Manduca-DH was shown to stimulate both fluid secretion and cyclic AMP production in Malpighian tubules from 1–12 h posteclosion Pieris rapae adults. The function of the peptide in Manduca sexta is discussed.

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.

Dependence of ion fluxes on fluid transport by rat proximal tubule

1986 ◽  
Vol 250 (4) ◽  
pp. F680-F689 ◽  
Author(s):  
K. Bomsztyk ◽  
F. S. Wright
Keyword(s):  
Proximal Tubule ◽  
Fluid Transport ◽  
Rat Kidney ◽  
Water Flux ◽  
Fluid Secretion ◽  
Proximal Convoluted Tubule ◽  
Ion Fluxes ◽  
Fluid Absorption ◽  
Fluid Flux ◽  
K Transport

The effects of changes in transepithelial water flux (Jv) on sodium, chloride, calcium, and potassium transport by the proximal convoluted tubule were examined by applying a microperfusion technique to surface segments in kidneys of anesthetized rats. Perfusion solutions were prepared with ion concentrations similar to those in fluid normally present in the later parts of the proximal tubule. Osmolality of the perfusate was adjusted with mannitol. With no mannitol in the perfusates, net fluid absorption was observed. Addition of increasing amounts of mannitol first reduced Jv to zero and then reversed net fluid flux. At the maximal rates of fluid absorption, net absorption of Na, Cl, Ca, and K was observed. When Jv was reduced to zero, Na, Cl, and Ca absorption were reduced and K entered the lumen. Na, Cl, and Ca secretion occurred in association with the highest rates of net fluid secretion. The lumen-positive transepithelial potential progressively increased as the net fluid flux was reduced to zero and then reversed. The results demonstrate that changes in net water flux can affect Na, Cl, Ca, and K transport by the proximal convoluted tubule of the rat kidney. These changes in net ion fluxes are not entirely accounted for by changes in bulk-phase transepithelial electrochemical gradients.

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.

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.

Transepithelial and intracellular potentials in isolated Malpighian tubules of tenebrionid beetle

1987 ◽  
Vol 252 (4) ◽  
pp. F645-F653 ◽  
Author(s):  
S. W. Nicolson ◽  
L. C. Isaacson
Keyword(s):  
Membrane Potential ◽  
Basal Membrane ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Bathing Medium ◽  
Intracellular Potentials ◽  
Tenebrionid Beetle ◽  
Fold Reduction ◽  
K Concentration ◽  
Opposing Effects

Malpighian tubules of Onymacris plana (Coleoptera: Tenebrionidae) have been isolated for measurement of transepithelial and intracellular potentials, before and during stimulation of fluid secretion. In a bathing medium resembling the hemolymph composition of the insect, the transepithelial potential (VT) was approximately 13 mV, lumen positive. VT was subject to drift and frequently showed super-imposed regular oscillations, which were apparently action potentials associated with contractions of muscle fibers running along the tubules. Although tubules of Onymacris are approximately 8 cm long, the basal membrane potential (Vb) did not vary with distance along the tubule, averaging -31 mV. Addition of adenosine 3',5'-cyclic monophosphate (cAMP) or diuretic hormone (DH) homogenate to the bathing medium had no effect on Vb, but opposing effects on VT: cAMP caused it to increase to 60 mV, whereas DH homogenate caused a rapid drop in VT to almost zero. Ion substitutions in the bathing medium showed that under control conditions beetle tubules possessed appreciable basal permeability to both K and Cl ions, with a 10-fold reduction in bath K concentration hyperpolarizing Vb by 54 mV. The basal K and Cl channels were partially blocked by barium and thiocyanate ions, respectively. Stimulation with cAMP increased the apical membrane potential (Va) and significantly reduced the Cl permeability of the basal membrane, whereas its Na permeability remained negligible.

Fluid secretion in glomerular renal proximal tubules of freshwater-adapted fish

1988 ◽  
Vol 254 (1) ◽  
pp. R154-R158 ◽  
Author(s):  
W. H. Cliff ◽  
K. W. Beyenbach
Keyword(s):  
Renal Function ◽  
Fluid Secretion ◽  
Tubular Secretion ◽  
Hormonal Control ◽  
Proximal Tubules ◽  
Renal Proximal Tubules ◽  
Urine Production ◽  
Nacl Secretion ◽  
Urine Formation ◽  
Control Fluid

Tubular secretion by renal proximal tubules, as a mechanism for delivering fluid and electrolytes to the urine, has received little attention in modern conceptions of renal function in vertebrates even though it is the mechanism for urine production in aglomerular fish. This report demonstrates that some proximal tubules of glomerular kidneys of freshwater-adapted euryhaline fish spontaneously secrete fluid. The fluid consists primarily of Na (138 mM) and Cl (160 mM). NaCl and fluid secretion can be stimulated by adenosine 3',5-cyclic monophosphate, suggesting that tubular fluid secretion is under hormonal control. Fluid secretion driven by NaCl secretion in glomerular proximal tubules of fish that already filter NaCl and water suggests that secretion of fluid and NaCl may play a fundamental role in vertebrate renal function beyond a preadaptation for aglomerular urine formation.

scholarly journals Physiological and structural maturation of a polarised epithelium: the Malpighian tubules of a blood-sucking insect, Rhodnius prolixus

1990 ◽  
Vol 96 (3) ◽  
pp. 537-547
Author(s):  
H. LE B. SKAER ◽  
J. B. HARRISON ◽  
S. H. P. MADDRELL
Keyword(s):  
Fluid Transport ◽  
Physiological Function ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Second Phase ◽  
Structural Development ◽  
Blood Sucking ◽  
Late Embryogenesis ◽  
Intercellular Contacts ◽  
Two Phases

The development of polarity in a simple epithelium, the Malpighian tubules of Rhodnius, is analysed both ultrastructurally and physiologically. The onset of physiological function, including fluid secretion and the transport of solutes, is determined in late embryos and young hatchling insects and compared with structural development in tubules over a similar period. Two phases of maturation, separated by several days, are detected. The first, during late embryogenesis, involves the development of mature intercellular contacts and the dilation of the lumen, and is associated with the ability to transport specific solutes. The second phase involves the elaboration of the apical and basal membranes and the generation of mitochondria, and is associated with the onset of fluid transport in the tubules and with feeding in 4-day-old hatchlings.

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