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.

Antagonistic control of fluid secretion by the Malpighian tubules ofTenebrio molitor: effects of diuretic and antidiuretic peptides and their second messengers

2002 ◽  
Vol 205 (4) ◽  
pp. 493-501 ◽  
Author(s):  
U. I. M. Wiehart ◽  
S. W. Nicolson ◽  
R. A. Eigenheer ◽  
D. A. Schooley
Keyword(s):  
Cyclic Amp ◽  
Cyclic Gmp ◽  
Second Messengers ◽  
Fluid Secretion ◽  
Tenebrio Molitor ◽  
Inhibitory Effect ◽  
Malpighian Tubules ◽  
Dependent Manner ◽  
Response Curves

SUMMARYFluid secretion by insect Malpighian tubules is controlled by haemolymph-borne factors. The mealworm Tenebrio molitor provides the first known example of antagonistic interactions between endogenous neuropeptides acting on Malpighian tubules. The two corticotropin-releasing-factor (CRF)-related diuretic peptides previously isolated from Tenebrio molitor, Tenmo-DH37 and Tenmo-DH47, were found to stimulate Tenebrio molitor tubules in vitro in a dose-dependent manner with EC50 values of 0.12 nmol l–1 and 26 nmol l–1 respectively. However, no synergistic or additive effect was observed when these two peptides were tested simultaneously. We then investigated antagonism between second messengers: dose–response curves were constructed for stimulation of Tenebrio molitor tubules by cyclic AMP and their inhibition by cyclic GMP. When both cyclic nucleotides were included in the bathing Ringer, the stimulatory effect of cyclic AMP was neutralised by cyclic GMP. Similarly, the stimulatory effect of Tenmo-DH37 was reversed on addition of an antidiuretic peptide (Tenmo-ADF), which was recently isolated from Tenebrio molitor and acts via cyclic GMP. The cardioacceleratory peptide CAP2b, originally isolated from Manduca sexta, also increases intracellular cyclic GMP levels and inhibited fluid secretion by Tenebrio molitor tubules, with an EC50 value of 85 nmol l–1. This inhibitory effect was reversed by Tenmo-DH37. Endogenous diuretic and antidiuretic peptides, effective at low concentrations and acting via antagonistic second messengers, have the potential for fine control of secretion rates in the Malpighian tubules of Tenebrio molitor.

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.

Active transport of sodium by the malpighian tubules of the tsetse fly Glossian morsitans

1976 ◽  
Vol 64 (2) ◽  
pp. 357-368
Author(s):  
J. D. Gee
Keyword(s):  
Cell Function ◽  
Malpighian Tubule ◽  
Active Role ◽  
Fluid Secretion ◽  
Sodium Concentration ◽  
Tsetse Fly ◽  
Malpighian Tubules ◽  
Bathing Solution ◽  
Bathing Medium

Isolated Malpighian tubules of Glossina morsitans are able to transport sodium against its concentration gradient. Their rate of secretion is dependent on the sodium concentration of the bathing medium. Potassium must be present in the bathing solution for rapid secretion to be maintained, but it does not play an active role in fluid secretion. Lithium and ammonium ions are able to substitute partially for sodium, other monovalent cations cannot. Ouabain does not affect rapid secretion by Glossina tubules in vitro. Conclusions drawn from the results are incorporated into a model of Malpighian tubule cell function in this insect.

scholarly journals Synergistic Activity between Statins and Bisphosphonates against Acute Experimental Toxoplasmosis

2017 ◽  
Vol 61 (8) ◽  
Author(s):  
Zhu-Hong Li ◽  
Catherine Li ◽  
Sergio H. Szajnman ◽  
Juan B. Rodriguez ◽  
Silvia N. J. Moreno
Keyword(s):  
Lethal Dose ◽  
Inhibitory Effect ◽  
Etiologic Agent ◽  
Farnesyl Diphosphate ◽  
Synergistic Activity ◽  
Content Type ◽  
Coa Reductase ◽  
Modest Effect

ABSTRACT Bisphosphonates are widely used for the treatment of bone disorders. These drugs also inhibit the growth of a variety of protozoan parasites, such as Toxoplasma gondii, the etiologic agent of toxoplasmosis. The target of the most potent bisphosphonates is the isoprenoid biosynthesis pathway enzyme farnesyl diphosphate synthase (FPPS). Based on our previous work on the inhibitory effect of sulfur-containing linear bisphosphonates against T. gondii, we investigated the potential synergistic interaction between one of these derivatives, 1-[(n-heptylthio)ethyl]-1,1-bisphosphonate (C7S), and statins, which are potent inhibitors of the host 3-hydroxy-3-methyl glutaryl-coenzyme A reductase (3-HMG-CoA reductase). C7S showed high activity against the T. gondii bifunctional farnesyl diphosphate (FPP)/geranylgeranyl diphosphate (GGPP) synthase (TgFPPS), which catalyzes the formation of FPP and GGPP (50% inhibitory concentration [IC50] = 31 ± 0.01 nM [mean ± standard deviation]), and modest effect against the human FPPS (IC50 = 1.3 ± 0.5 μM). We tested combinations of C7S with statins against the in vitro replication of T. gondii. We also treated mice infected with a lethal dose of T. gondii with similar combinations. We found strong synergistic activities when using low doses of C7S, which were stronger in vivo than when tested in vitro. We also investigated the synergism of several commercially available bisphosphonates with statins both in vitro and in vivo. Our results provide evidence that it is possible to develop drug combinations that act synergistically by inhibiting host and parasite enzymes in vitro and in vivo.

In Vitro Inhibition of Blood Coagulation by Tripeptide Aldehydes - A Retrospective Screening Study Focused on the Stable D-MePhe-Pro-Arg-H · H2SO4

1992 ◽  
Vol 67 (03) ◽  
pp. 325-330 ◽  
Author(s):  
Daniel Bágdy ◽  
Èva Barabás ◽  
Sándor Bajusz ◽  
Erzsébet Széll
Keyword(s):  
Blood Coagulation ◽  
Plasma Proteins ◽  
Anticoagulant Activity ◽  
Coagulation Factors ◽  
Inhibitory Effect ◽  
Inhibitory Potency ◽  
Peptide Aldehydes ◽  
Screening Study ◽  
Tissue Homogenates

SummaryA series of peptide aldehydes synthetized in our institute during the last 15 years were screened to detect their inhibitory effect on blood coagulation. Simple conventional clotting assays, platelet function tests and fibrinolytic methods were used to evaluate the inhibitory potency of the compounds in complex clotting systems as well as their supposed antifibrinolytic effect in vitro. Special attention was paid to the possible interactions with blood cells and plasma proteins, and to the functional stability of the inhibitors in several tissue homogenates. D-Phe-Pro-Arg-H (GYKI-14166, RGH-2958), Boc-D-Phe-Pro-Arg-H (GYKI-14451) and D-MePhe-Pro-Arg-H (GYKI-14766) were found to be the most potent inhibitors. The peptide aldehydes via formation of reversible complexes with thrombin impede the enzyme to react with the coagulation factors, platelet membrane and vessel wall. The compounds inhibit platelet aggregation induced by thrombin specifically without changing the sensitivity of platelets to other inducers. D-Phe-Pro-Arg-H and D-MePhe-Pro-Arg-H showed no antifibrinolytic effect. D-MePhe-Pro-Arg-H and Boc-D-Phe-Pro-Arg-H proved to be stable in dry state for years and in solution at room temperature for several days. The anticoagulant activity of the compounds was declared in NIH antithrombin units.

A novel plant-derived inhibitor of cAMP-mediated fluid and chloride secretion

1999 ◽  
Vol 276 (1) ◽  
pp. G58-G63 ◽  
Author(s):  
S. E. Gabriel ◽  
S. E. Davenport ◽  
R. J. Steagall ◽  
V. Vimal ◽  
T. Carlson ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Ussing Chamber ◽  
Fluid Secretion ◽  
Chloride Secretion ◽  
Inhibitory Effect ◽  
Adult Mice ◽  
Dependent Inhibition ◽  
Chamber Studies

We have identified an agent (SP-303) that shows efficacy against in vivo cholera toxin-induced fluid secretion and in vitro cAMP-mediated Cl−secretion. Administration of cholera toxin to adult mice results in an increase in fluid accumulation (FA) in the small intestine (FA ratio = 0.63 vs. 1.86 in control vs. cholera toxin-treated animals, respectively). This elevation in FA induced by cholera toxin was significantly reduced (FA ratio = 0.70) in animals treated with a 100 mg/kg dose of SP-303 at the same time as the cholera treatment. Moreover, when SP-303 was administered 3 h after cholera toxin, a dose-dependent inhibition of FA levels was observed with a half-maximal inhibitory dose of 10 mg/kg. In Ussing chamber studies of Caco-2 or T84 monolayer preparations, SP-303 had a significant effect on both basal current and forskolin-stimulated Cl−current. SP-303 also induced an increase in resistance that paralleled the observed decrease in current. These data suggest that SP-303 has an inhibitory effect on cAMP-mediated Cl−and fluid secretion. Thus SP-303 may prove to be a useful broad-spectrum antidiarrheal agent.

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 Nutritional Value and Biological Activity of Gluten-Free Bread Enriched with Cricket Powder

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1184
Author(s):  
Przemysław Łukasz Kowalczewski ◽  
Małgorzata Gumienna ◽  
Iga Rybicka ◽  
Barbara Górna ◽  
Paulina Sarbak ◽  
...  
Keyword(s):  
Biological Activity ◽  
Nutritional Value ◽  
Food Products ◽  
In Vitro Digestion ◽  
Free Food ◽  
Inhibitory Effect ◽  
Polyphenolic Compounds ◽  
Acheta Domesticus ◽  
Gluten Free

Cricket powder, described in the literature as a source of nutrients, can be a valuable ingredient to supplement deficiencies in various food products. Work continues on the implementation of cricket powder in products that are widely consumed. The aim of this study was to obtain gluten-free bread with a superior nutritional profile by means of insect powder addition. Gluten-free breads enriched with 2%, 6%, and 10% of cricket (Acheta domesticus) powder were formulated and extensively characterized. The nutritional value, as well as antioxidant and β-glucuronidase activities, were assessed after simulated in vitro digestion. Addition of cricket powder significantly increased the nutritional value, both in terms of the protein content (exceeding two-, four-, and seven-fold the reference bread (RB), respectively) and above all mineral compounds. The most significant changes were observed for Cu, P, and Zn. A significant increase in the content of polyphenolic compounds and antioxidant activity in the enriched bread was also demonstrated; moreover, both values additionally increased after the digestion process. The total polyphenolic compounds content increased about five-fold from RB to bread with 10% CP (BCP10), and respectively about three-fold after digestion. Similarly, the total antioxidant capacity before digestion increased about four-fold, and after digestion about six-fold. The use of CP also reduced the undesirable activity of β-glucuronidase by 65.9% (RB vs. BCP10) in the small intestine, down to 78.9% in the large intestine. The influence of bread on the intestinal microflora was also evaluated, and no inhibitory effect on the growth of microflora was demonstrated, both beneficial (Bifidobacterium and Lactobacillus) and pathogenic (Enterococcus and Escherichia coli). Our results underscore the benefits of using cricket powder to increase the nutritional value and biological activity of gluten-free food products.

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