Changes in fluid secretion rate alter net transepithelial transport of MRP2 and P-glycoprotein substrates in Malpighian tubules ofDrosophila melanogaster

2006 ◽  
Vol 63 (3) ◽  
pp. 123-134 ◽  
Author(s):  
Michael J. O'Donnell ◽  
John P. Leader
Keyword(s):  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Transepithelial Transport ◽  
P Glycoprotein

scholarly journals P-glycoprotein Detoxification by the Malpighian Tubules of the Desert Locust

2019 ◽  
Author(s):  
Marta Rossi ◽  
Davide De Battisti ◽  
Jeremy E. Niven
Keyword(s):  
Surface Area ◽  
Rhodamine B ◽  
Ex Vivo ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Desert Locust ◽  
P Glycoprotein ◽  
Transporter Family ◽  
Wide Range

ABSTRACTDetoxification is essential for allowing animals to remove toxic substances present in their diet or generated as a biproduct of their metabolism. By transporting a wide range of potentially noxious substrates, active transporters of the ABC transporter family play an important role in detoxification. One such class of transporters are the multidrug resistance P-glycoprotein transporters. Here, we investigated P-glycoprotein transport in the Malpighian tubules of the desert locust (Schistocerca gregaria), a species whose diet includes plants that contain toxic secondary metabolites. To this end, we studied transporter physiology using a modified Ramsay assay in which ex vivo Malpighian tubules are incubated in different solutions containing the P-glycoprotein substrate dye rhodamine B in combination with different concentrations of the P-glycoprotein inhibitor verapamil. Our evidence shows that: (i) the Malpighian tubules contain a P-glycoprotein; (ii) tubule surface area is positively correlated with the tubule fluid secretion rate; and (iii) as the fluid secretion rate increases so too does the net extrusion of rhodamine B. We were able to quantify precisely the relationships between the fluid secretion, surface area, and net extrusion. We interpret these results in the context of the life history and foraging ecology of desert locusts. We argue that P-glycoproteins play an important role in the detoxification by contributing to the removal of xenobiotic substances from the haemolymph, thereby enabling gregarious desert locusts to maintain toxicity through the ingestion of toxic plants without suffering the deleterious effects themselves.

scholarly journals Malpighamoeba infection compromises fluid secretion and P-glycoprotein detoxification in Malpighian tubules

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marta Rossi ◽  
Swidbert R. Ott ◽  
Jeremy E. Niven
Keyword(s):  
Water Stress ◽  
Surface Area ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Energy Costs ◽  
Natural Environments ◽  
Desert Locust ◽  
P Glycoprotein ◽  
The Impact

Abstract Malpighian tubules, analogous to vertebrate nephrons, play a key role in insect osmoregulation and detoxification. Tubules can become infected with a protozoan, Malpighamoeba, which damages their epithelial cells, potentially compromising their function. Here we used a modified Ramsay assay to quantify the impact of Malpighamoeba infection on fluid secretion and P-glycoprotein-dependent detoxification by desert locust Malpighian tubules. Infected tubules have a greater surface area and a higher fluid secretion rate than uninfected tubules. Infection also impairs P-glycoprotein-dependent detoxification by reducing the net rhodamine extrusion per surface area. However, due to the increased surface area and fluid secretion rate, infected tubules have similar total net extrusion per tubule to uninfected tubules. Increased fluid secretion rate of infected tubules likely exposes locusts to greater water stress and increased energy costs. Coupled with reduced efficiency of P-glycoprotein detoxification per surface area, Malpighamoeba infection is likely to reduce insect survival in natural environments.

scholarly journals Malpighamoeba infection compromises fluid secretion and P-glycoprotein detoxification in Malpighian tubules

2019 ◽  
Author(s):  
Marta Rossi ◽  
Swidbert R. Ott ◽  
Jeremy E. Niven
Keyword(s):  
Water Stress ◽  
Surface Area ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Secretion Rate ◽  
Energy Costs ◽  
Natural Environments ◽  
Desert Locust ◽  
P Glycoprotein ◽  
The Impact

AbstractMalpighian tubules, analogous to vertebrate nephrons, play a key role in insect osmoregulation and detoxification. Tubules can become infected with a protozoan, Malpighamoeba, which damages their epithelial cells, potentially compromising their function. Here we used a modified Ramsay assay to quantify the impact of Malpighamoeba infection on fluid secretion and P-glycoprotein-dependent detoxification by desert locust Malpighian tubules. Infected tubules have a greater surface area and a higher fluid secretion rate than uninfected tubules. Infection also impairs P-glycoprotein-dependent detoxification by reducing the net rhodamine extrusion per surface area. However, due to the increased surface area and fluid secretion rate, infected tubules have similar total net extrusion per tubule to uninfected tubules. Increased fluid secretion rate of infected tubules likely exposes locusts to greater water stress and increased energy costs. Coupled with reduced efficiency of P-glycoprotein detoxification per surface area, Malpighamoeba infection is likely to reduce insect survival in natural environments.

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.

Central role of the apical membrane H+-ATPase in electrogenesis and epithelial transport in Malpighian tubules

2000 ◽  
Vol 203 (9) ◽  
pp. 1459-1468 ◽  
Author(s):  
K.W. Beyenbach ◽  
T.L. Pannabecker ◽  
W. Nagel
Keyword(s):  
Epithelial Transport ◽  
Apical Membrane ◽  
Short Circuit ◽  
Basolateral Membrane ◽  
Electrical Coupling ◽  
Short Circuit Current ◽  
Fluid Secretion ◽  
Malpighian Tubules ◽  
Proton Channel ◽  
Transepithelial Transport

The effects of bafilomycin A(1), a blocker of V-type H(+)-ATPases, were investigated in Malpighian tubules of Aedes aegypti. Bafilomycin A(1) reduced rates of transepithelial fluid secretion and the virtual short-circuit current (vI(sc)) with an IC(50) of approximately 5 micromol l(−)(1). As vI(sc) decreased, the electrical resistance increased across the whole epithelium and across the apical membrane, indicating effects on electroconductive pathways. Bafilomycin A(1) had no effect when applied from the tubule lumen, pointing to the relative impermeability of the apical membrane to bafilomycin A(1). Thus, bafilomycin A(1) must take a cytoplasmic route to its blocking site in the proton channel of the H(+)-ATPase located in the apical membrane of principal cells. The inhibitory effects of bafilomycin A(1) were qualitatively similar to those of dinitrophenol in that voltages across the epithelium (V(t)), the basolateral membrane (V(bl)) and the apical membrane (V(a)) depolarized towards zero in parallel. Moreover, V(bl)always tracked V(a), indicating electrical coupling between the two membranes through the shunt. Electrical coupling allows the H(+)-ATPase to energize not only the apical membrane, but also the basolateral membrane. Furthermore, electrical coupling offers a balance between electroconductive entry of cations across the basolateral membrane and extrusion across the apical membrane to support steady-state conditions during transepithelial transport.

scholarly journals Transepithelial transport of P-glycoprotein substrate by the Malpighian tubules of the desert locust

PLoS ONE ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. e0223569 ◽  
Author(s):  
Marta Rossi ◽  
Davide De Battisti ◽  
Jeremy Edward Niven
Keyword(s):  
Malpighian Tubules ◽  
Transepithelial Transport ◽  
Desert Locust ◽  
P Glycoprotein

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.

Transepithelial transport of nicotine and vinblastine in isolated malpighian tubules of the tobacco hornworm (Manduca sexta) suggests a P-glycoprotein-like mechanism.

1998 ◽  
Vol 201 (18) ◽  
pp. 2637-2645 ◽  
Author(s):  
L S Gaertner ◽  
C L Murray ◽  
C E Morris
Keyword(s):  
Manduca Sexta ◽  
Electrical Potential ◽  
Tobacco Hornworm ◽  
Malpighian Tubules ◽  
Transepithelial Transport ◽  
Multidrug Transporter ◽  
Basal Surface ◽  
P Glycoprotein ◽  
Apical Side ◽  
Vectorial Transport

We have examined the accumulative transport properties of the Malpighian (excretory) tubules of the tobacco hornworm Manduca sexta to test the hypothesis that a P-glycoprotein-like multidrug transporter is active and is responsible for the excretion of dietary nicotine in this tissue. Isolated tubules were cannulated and exposed to radiolabelled forms of either nicotine (5 min exposure) or the P-glycoprotein substrate vinblastine (60 min exposure) in the bathing (basal surface) fluid. The luminal (apical) contents were then flushed, and lumen-to-bath ratios were measured. Although these ratios provide conservative estimates of the physiological ability of Malpighian tubules to move compounds from blood to lumen, tubules concentrated nicotine 10-fold from an initial bath concentration of 0.5 mmol l-1 and vinblastine threefold (from an initial concentration of 1 micromol l-1). Vectorial transport of vinblastine and nicotine was eliminated by 25 micromol l-1 verapamil (a P-glycoprotein inhibitor) and was not dependent on the presence of a transepithelial electrical potential. Nicotine transport was inhibited by atropine (3 mmol l-1), while nicotine (> or = 50 micromol l-1) significantly reduced vinblastine transport. Verapamil was effective at reducing vinblastine transport when applied to the basal side alone, but not when applied to the apical side alone. Taken together, these results are consistent with the idea that the active excretion of nicotine and other alkaloids by the tobacco hornworm is mediated by a P-glycoprotein-like mechanism.

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