A Study of the Malpighian Tubules of the Pill Millipede, Glomeris marginata (Villers)

1974 ◽  
Vol 60 (1) ◽  
pp. 13-28
Author(s):  
PATRICIA ANNE FARQUHARSON
Keyword(s):  
Resistance Mechanism ◽  
Ringer Solution ◽  
Malpighian Tubules ◽  
Metabolic Inhibitors ◽  
Bathing Medium ◽  
Diuretic Hormone ◽  
Fluid Production ◽  
Tubule Fluid ◽  
Secretion Rates

1. The Malphigian tubules of the pill millipede, Glomeris marginata are described. 2. After the necessary analyses of the haemolymph had been carried out a Ringer solution was prepared which would support the secretion of tubule fluid in vitro. 3. The reasons for the variation and deterioration in the secretion rates of control tubules are discussed. The presence of various amino acids in the bathing medium appears to be essential for fluid production. 4. There would not appear to be a diuretic hormone involved in the control of secretion; and 5-HT, cylic AMP and theophylline will not stimulate fluid production. 5. Secretion is inhibited by the metabolic inhibitors 2,4-DNP, azide and cyanide. The relative insensitivity shown to the latter two compounds is probably associated with a resistance mechanism.

The excretion of NaCl and KCl loads in mosquitoes. 1. Control data

2014 ◽  
Vol 307 (7) ◽  
pp. R837-R849 ◽  
Author(s):  
Rebecca M. Hine ◽  
Matthew F. Rouhier ◽  
Seokhwan Terry Park ◽  
Zhijun Qi ◽  
Peter M. Piermarini ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Rapid Onset ◽  
Ringer Solution ◽  
Tubular Secretion ◽  
Malpighian Tubules ◽  
Control Data ◽  
Diuretic Hormone

The handling of Na+ and K+ loads was investigated in isolated Malpighian tubules and in whole mosquitoes of Aedes aegypti. Isolated Malpighian tubules bathed in Na+-rich Ringer solution secreted Na+-rich fluid, and tubules bathed in K+-rich Ringer solution secreted K+-rich fluid. Upon Na+ loading the hemolymph, the mosquito removed 77% the injected Na+ within the next 30 min. The rapid onset and magnitude of this diuresis and the excretion of more Na+ than can be accounted for by tubular secretion in vitro is consistent with the release of the calcitonin-like diuretic hormone in the mosquito to remove the Na+ load from the hemolymph. Downstream, K+ was reabsorbed with water in the hindgut, which concentrated Na+ in excreted urine hyperosmotic to the hemolymph. Upon K+ loading the hemolymph, the mosquito took 2 h to remove 100% of the injected K+ from the hemolymph. The excretion of K+-rich isosmotic urine was limited to clearing the injected K+ from the hemolymph with a minimum of Cl− and water. As a result, 43.3% of the injected Cl− and 48.1% of the injected water were conserved. The cation retained in the hemolymph with Cl− was probably N-methyl-d-glucamine, which replaced Na+ in the hemolymph injection of the K+ load. Since the tubular secretion of K+ accounts for the removal of the K+ load from the hemolymph, the reabsorption of K+, Na+, Cl−, and water must be inhibited in the hindgut. The agents mediating this inhibition are unknown.

The influence of Blastocrithidia triatomae (Trypanosomatidae) on the reduviid bug Triatoma infestans: in vivo and in vitro diuresis and production of diuretic hormone

Parasitology ◽  
1988 ◽  
Vol 96 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Antonia Schnitker ◽  
G. A. Schaub ◽  
S. H. P. Maddrell
Keyword(s):  
Malpighian Tubules ◽  
Triatoma Infestans ◽  
Diuretic Hormone ◽  
Ultrastructural Alterations ◽  
Secretion Rates

SUMMARYThe homoxenous flagellate Blastocrithidia triatomae disturbs excretion in Triatoma infestans. During the first 4 and 24 h after feeding, infected 5th instars excreted approximately a 2·5-fold smaller volume of urine. Consequently, about double the normal volume of haemolymph could be obtained from these infected bugs 24 h after feeding. Surprisingly, the in vitro secretion rates of Malpighian tubules from uninfected and infected bugs were nearly identical. In addition, the storage and release of diuretic hormone in infected bugs was sufficient to induce normal secretion rates by isolated Malpighian tubules. Therefore, the previously observed ultrastructural alterations in the upper Malpighian tubules of infected bugs do not result in a disturbed in vitro secretion, although in vivo excretion is reduced.

A Study of the Malpighian Tubules of the Pill Millipede, Glomeris marginata (Villers)

1974 ◽  
Vol 60 (1) ◽  
pp. 41-51
Author(s):  
PATRICIA ANNE FARQUHARSON
Keyword(s):  
Size Distribution ◽  
Fluid Transport ◽  
Molecular Size ◽  
Malpighian Tubules ◽  
Inverse Relation ◽  
Fluid Production ◽  
Molecular Size Distribution ◽  
Molecular Sieving ◽  
Tubule Fluid ◽  
Tubule Wall

1. Tubule fluid:medium ratios (TF/M) have been measured for inulin, glucose, LMWD and HMWD. These TF/M ratios were surprisingly high. 2. The tubule appears to act as a molecular filter; that is to say, molecules move through the tubule wall in inverse relation to their size. This is best illustrated using polyvinyl pyrrolidone as a tracer. The molecular size distribution of PVP fractions present in tubule fluid differs markedly from the molecular size distribution of PVP in the bathing Ringer. 3. No correlation can be made between the inulin and glucose TF/M and the rate of fluid production. However, the inverse relationship between TF/M and rate of fluid production for dextrans indicates a molecular sieving effect. 4. The significance of these results is discussed with reference to models of fluid transport.

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.

Effects of hypophysectomy and subsequent FSH and testosterone treatment on inhibin production by adult rat testes

1985 ◽  
Vol 105 (1) ◽  
pp. 1-6 ◽  
Author(s):  
C. L. Au ◽  
D. M. Robertson ◽  
D. M. de Kretser
Keyword(s):  
Seminiferous Tubule ◽  
Hormonal Control ◽  
Human Chorionic Gonadotrophin ◽  
Experimental Conditions ◽  
Adult Rats ◽  
Adult Rat ◽  
Fluid Production ◽  
Tubule Fluid

ABSTRACT The hormonal control of inhibin production by adult rat testes was investigated using an in-vitro inhibin bioassay validated for the measurement of inhibin activity in charcoal-treated rat testicular extracts. The effect of hypophysectomy examined at 16 h, 3, 7 and 42 days after surgery showed a decrease in testicular inhibin content and seminiferous tubule fluid production by 7 days and a decrease in inhibin production by 42 days. Serum FSH and LH were suppressed 3 days after surgery. In 30-day chronically hypophysectomized adult rats treated for 3 days with twice daily s.c. injections of (a) human FSH (hFSH, 22 i.u./rat per day), (b) testosterone (5 mg/rat per day), (c) hFSH + testosterone (same doses as a and b), or (d) human chorionic gonadotrophin (hCG, 12 i.u./rat per day), hFSH or hFSH and testosterone stimulated an increase in testicular inhibin content but not in inhibin production or tubule fluid production. Testosterone and hCG had no effect on these parameters. It is concluded that in vivo, FSH alone stimulates an increase in testicular inhibin content. The failure to observe an increase in inhibin production in vivo is attributed to the suppression of seminiferous tubule fluid production under the same experimental conditions. J. Endocr. (1985) 105, 1–6

Horseradish peroxidase transport across rabbit jejunum and Peyer's patches in vitro

1983 ◽  
Vol 245 (1) ◽  
pp. G54-G58 ◽  
Author(s):  
R. Ducroc ◽  
M. Heyman ◽  
B. Beaufrere ◽  
J. L. Morgat ◽  
J. F. Desjeux
Keyword(s):  
Horseradish Peroxidase ◽  
Ringer Solution ◽  
Peyer's Patches ◽  
Metabolic Inhibitors ◽  
Peyer’S Patches ◽  
Significant Difference ◽  
Rabbit Jejunum ◽  
Hrp Transport ◽  
Uptake And Transport

Uptake and transport of horseradish peroxidase (HRP) have been observed in both Peyer's patches (PP) and jejunal epithelium (JE), and the quantities transported across each tissue were compared. Steady-state was reached much faster in PP than in JE. In Ringer solution, no significant difference was found between the HRP fluxes conveyed through PP and JE. In the presence of 10 mM glucose, slight net secretion was observed in JE but not in PP. In both tissues, the transport mechanism was shown to be sensitive to metabolic inhibitors. By contrast, in PP, ammonia did not significantly enhance intact HRP fluxes. Intracellular transfer and catabolism were estimated by measuring transepithelial fluxes of tritiated HRP. In PP, fluxes from mucosa to serosa and from serosa to mucosa were both greatly reduced (9.18 +/- 3.9 and 10.5 +/- 5.1 pmol X h-1 X cm-2, respectively) compared with JE (106.02 +/- 16 and 31.3 +/- 9.3). These results indicate that intact HRP fluxes are similar in PP and JE, but that tritiated HRP fluxes (intact plus degraded HRP fluxes) are smaller in PP. Together, these results suggest that the specific characteristics of HRP transport across PP are fast uptake and reduced degradation.

scholarly journals Excretion of NaCl and KCl loads in mosquitoes. 2. Effects of the small molecule Kir channel modulator VU573 and its inactive analog VU342

2014 ◽  
Vol 307 (7) ◽  
pp. R850-R861 ◽  
Author(s):  
Matthew F. Rouhier ◽  
Rebecca M. Hine ◽  
Seokhwan Terry Park ◽  
Rene Raphemot ◽  
Jerod Denton ◽  
...  
Keyword(s):  
Urinary Excretion ◽  
Small Molecules ◽  
Fluid Secretion ◽  
Ringer Solution ◽  
Malpighian Tubules ◽  
Kir Channel ◽  
Channel Modulator ◽  
Inactive Analog

The effect of two small molecules VU342 and VU573 on renal functions in the yellow fever mosquito Aedes aegypti was investigated in vitro and in vivo. In isolated Malpighian tubules, VU342 (10 μM) had no effect on the transepithelial secretion of Na+, K+, Cl−, and water. In contrast, 10 μM VU573 first stimulated and then inhibited the transepithelial secretion of fluid when the tubules were bathed in Na+-rich or K+-rich Ringer solution. The early stimulation was blocked by bumetanide, suggesting the transient stimulation of Na-K-2Cl cotransport, and the late inhibition of fluid secretion was consistent with the known block of AeKir1, an Aedes inward rectifier K+ channel, by VU573. VU342 and VU573 at a hemolymph concentration of about 11 μM had no effect on the diuresis triggered by hemolymph Na+ or K+ loads. VU342 at a hemolymph concentration of 420 μM had no effect on the diuresis elicited by hemolymph Na+ or K+ loads. In contrast, the same concentration of VU573 significantly diminished the Na+ diuresis by inhibiting the urinary excretion of Na+, Cl−, and water. In K+-loaded mosquitoes, 420 μM VU573 significantly diminished the K+ diuresis by inhibiting the urinary excretion of K+, Na+, Cl−, and water. We conclude that 1) the effects of VU573 observed in isolated Malpighian tubules are overwhelmed in vivo by the diuresis triggered with the coinjection of Na+ and K+ loads, and 2) at a hemolymph concentration of 420 μM VU573 affects Kir channels systemically, including those that might be involved in the release of diuretic hormones.

scholarly journals The Coupling of the Short-Circuit Current to Metabolism in the Urinary Bladder of the Toad

1963 ◽  
Vol 46 (4) ◽  
pp. 733-754 ◽  
Author(s):  
Roy H. Maffly ◽  
I. S. Edelman
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Metabolic Effects ◽  
Metabolic Inhibitors ◽  
Na Transport ◽  
Bathing Medium ◽  
Free Media ◽  
Tricarboxylic Acid Cycle Intermediates

The relationship of the short-circuit current to metabolism was studied in the toad bladder in vitro. Substrates and inhibitors were added to the bathing medium and the effect on the short-circuit current was determined. The spontaneous decline in the short-circuit current that occurred in substrate-free media was prevented or reversed by the addition of glucose, pyruvate, lactate, or ß-hydroxybutyrate, whereas acetate and tricarboxylic acid cycle intermediates had no effect. A variety of metabolic inhibitors depressed the short-circuit current; depression by iodoacetate and by malonate was delayed by prior addition of pyruvate or lactate but not by glucose. The ability of a substrate to stimulate the current did not correlate with its rate of oxidation to CO2. On the basis of earlier studies, the metabolic effects on the short-circuit current were assumed to reflect equivalent effects on the rate of active Na transport. It is suggested that the energy for Na transport is provided not by a general cellular metabolic pool but by a specific metabolic pathway or pathways spatially linked to the transport mechanism.

Nicotinamide uptake and metabolism by chick intestine

1983 ◽  
Vol 245 (4) ◽  
pp. G531-G538
Author(s):  
S. A. Schuette ◽  
R. C. Rose
Keyword(s):  
Metabolic Inhibitors ◽  
Isolated Cells ◽  
Physiological Concentration ◽  
Bathing Medium ◽  
Intracellular Space ◽  
Nicotinamide Mononucleotide ◽  
Mucosal Cells ◽  
Uptake And Metabolism

Intestinal uptake and metabolism of nicotinamide (NAm) were studied in isolated epithelial cells and in isolated segments in situ at a physiological concentration of [14C]NAm (11.7 microM). [14C]NAm was rapidly taken up from the bathing medium and largely metabolized to [14C]NAD by the isolated cells. Total accumulation of 14C label was energy dependent and saturable at higher concentrations of NAm (148 and 351 microM). In contrast, the tissue content of NAm was unaffected by metabolic inhibitors, and the bathing media NAm rapidly equilibrated with intracellular space at all levels of NAm. NAm was converted directly to NAD via the intermediate nicotinamide mononucleotide (NMN); nicotinic acid was not an intermediate in this conversion and was a less efficient precursor of NAD. NAm absorption in vivo was substantial, 30.6% of dose after 10 min. Also, data on NAm entry into the mucosa and subsequent metabolism in vivo supported the in vitro observations. Exogenous NMN reduced NAm entry into the mucosal cells both in vivo and in vitro; the effect was specific to NAm. This is the only suggestion to date that NAm entry might proceed by some form of specialized transport process.

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.

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