Analysis of Tubule Fluid

1978 ◽  
pp. 105-140 ◽  
Author(s):  
R. Greger ◽  
F. Lang ◽  
F. G. Knox ◽  
C. Lechene
Keyword(s):  
Tubule Fluid

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.

Metabolic Support of Chloride-dependent Short-circuit Current Across Locust Rectum

1982 ◽  
Vol 99 (1) ◽  
pp. 349-362
Author(s):  
M. CHAMBERLIN ◽  
J. E. PHILLIPS
Keyword(s):  
Cyclic Amp ◽  
Short Circuit ◽  
Malpighian Tubule ◽  
Short Circuit Current ◽  
Metabolic Substrates ◽  
Endogenous Substrates ◽  
Tubule Fluid ◽  
Substrate Source ◽  
Stimulation Of

1. Recta of desert locusts were short-circuited and depleted of endogenous substrates by exposing them to saline containing cyclic AMP but no metabolites. Individual substrates were then added to substrate-depleted recta and the change in short-circuit current (Isc) monitored. 2. Proline or glucose (50 mM) caused by far the largest increase in Isc of all substrates tested. Stimulation of the Isc by proline was not dependent upon external sodium, but did require external chloride. 3. Physiological levels of proline also caused a large increase in Isc, while physiological levels of glucose produced a much smaller stimulation. Over 90% of the proline-dependent Isc stimulation can be produced by adding 15 mM proline solely to the lumen side of the tissue. 4. These results are discussed with regard to rectal oxidative metabolism and availability of metabolic substrates in vivo. High levels of proline in Malpighian tubule fluid are probably the major substrate source for rectal Cl−transport. Note:

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.

Acute effect of salmon calcitonin on renal magnesium transport in the magnesium-loaded rat

1986 ◽  
Vol 64 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Denis R. Roy
Keyword(s):  
Significant Relationship ◽  
Salmon Calcitonin ◽  
Acute Effect ◽  
Magnesium Concentration ◽  
Thick Ascending Limb ◽  
Group 3 ◽  
Group 2 ◽  
Magnesium Excretion ◽  
Tubule Fluid ◽  
Group 1

The present studies were undertaken to examine whether salmon calcitonin, by increasing magnesium reabsorption in the thick ascending limb, and presumably the tubulointerstitial magnesium concentration gradient, would lead to an increase in fractional magnesium delivery to the end-descending limb (magnesium secretion) in magnesium-loaded rats. Thyroparathyroidectomized, postprandial Munich–Wistar rats were prepared for micropuncture of papillary end-descending limbs and of superficial end-accessible proximal tubules. Group 1 served as clonidine–water diuresis time controls; group 2 was treated as group 1 but also received synthetic salmon calcitonin (10 mU/min); and group 3 was treated as group 2 but also received calcium chloride intravenously. Calcitonin, alone or with calcium, produced a significant fall in fractional magnesium excretion. A significant relationship was also observed between fractional magnesium excretion and urine flow rate (r = 0.56, p < 0.01). Calcitonin did not modify fractional magnesium delivery to the end-descending limb. A highly significant relationship was observed between tubule fluid-to-ultrafiltrate magnesium ratio and tubule fluid-to-plasma inulin ratio (r = 0.88, p < 0.001). Within each group, fractional magnesium delivery to the end-descending limb was similar to the corresponding value in the superficial end-accessible proximal tubule. Our results suggest that despite intense magnesium reabsorption, presumably in the thick ascending limb, magnesium secretion does not occur in the juxtameduilary pars recta and (or) thin descending limb.

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

Excretion in the house cricket: stimulation of rectal reabsorption by homogenates of the corpus cardiacum

1993 ◽  
Vol 185 (1) ◽  
pp. 305-323 ◽  
Author(s):  
J. H. Spring ◽  
S. A. Albarwani
Keyword(s):  
Time Course ◽  
Chloride Transport ◽  
Malpighian Tubule ◽  
Acheta Domesticus ◽  
Rectal Absorption ◽  
K Uptake ◽  
House Cricket ◽  
Tubule Fluid ◽  
Stimulation Of

1. We describe an in vitro perfused preparation of Acheta domesticus rectum which allows direct comparison of Malpighian tubule secretion and rectal absorption under identical conditions. Rectal absorption is stimulated four- to sixfold by corpora cardiaca (CC) homogenates and the stimulated rate is sufficiently rapid to account for all the fluid secreted by the tubules. 2. The time course for increased fluid absorption is similar to that required to stimulate electrogenic chloride transport in locusts and grasshoppers. Chloride is rapidly absorbed by the rectum under all conditions, along with lesser amounts of Na+ and K+. Unlike the situation in locusts, K+ uptake is unaffected by CC homogenates and the stimulated absorbate is NaCl-rich, similar in composition to the NaCl-rich tubule fluid produced under stimulated conditions. The absorbate is always slightly hypo-osmotic to the perfusate, reaching a maximum differential of approximately 15 mosmol l-1 following CC stimulation. 3. The antidiuretic factor that reduces tubule secretion does not promote fluid reabsorption by the rectum.

Mechanism of ammonia secretion by cortical collecting ducts of rabbits

1984 ◽  
Vol 247 (5) ◽  
pp. F729-F738 ◽  
Author(s):  
M. A. Knepper ◽  
D. W. Good ◽  
M. B. Burg
Keyword(s):  
Fluid Transport ◽  
Collecting Duct ◽  
Bicarbonate Secretion ◽  
Duct System ◽  
Major Site ◽  
Acid Ph ◽  
Collecting Ducts ◽  
Total Ammonia ◽  
Ammonia Addition ◽  
Tubule Fluid

The collecting duct system is a major site of ammonia addition to the tubule fluid. To study the mechanisms involved, we measured total ammonia and total CO2 transport in isolated, perfused cortical collecting ducts (CCD) from deoxycorticosterone-(DOC) treated rabbits. Perfusate and bath solutions contained 25 meq/liter HCO3 and 4 mM total ammonia. Net fluid transport was not significantly different from zero. Net secretion of total CO2 occurred in all tubules (mean collected concentration, 44.2 mM). Despite bicarbonate secretion, there was net secretion of total ammonia (mean collected concentration, 6.4 mM). There was no detectable ammonia addition to the collected fluid when ammonia was excluded from the perfusate and bath, ruling out a major contribution from synthesis. Ouabain did not significantly affect net transport of total ammonia or total CO2. To test the hypothesis that an acid pH disequilibrium may lower the luminal pH enough to drive ammonia secretion by nonionic diffusion, we perfused CCD from DOC-treated rabbits with carbonic anhydrase (CA) (0.1 mg/ml). Without CA, there was net total ammonia secretion (-2.2 pmol X min-1 X mm-1) and net total CO2 secretion (-16.6 pmol X min-1 X mm-1). Luminal CA converted the net total ammonia secretion to net absorption (1.0 pmol X min-1 X mm-1) while the bicarbonate secretion persisted (-11.2 pmol X min X mm-1). We conclude that total ammonia secretion in these tubules occurs primarily by diffusion of NH3 and is dependent on a luminal acid pH disequilibrium.

Calcium transport across the pars recta of cortical segment 2 proximal tubules

1986 ◽  
Vol 251 (4) ◽  
pp. F718-F724
Author(s):  
J. E. Bourdeau
Keyword(s):  
Proximal Tubule ◽  
Driving Forces ◽  
Proximal Tubules ◽  
Ion Diffusion ◽  
Low Concentrations ◽  
Pars Recta ◽  
Transepithelial Voltage ◽  
Lower Temperature ◽  
Tubule Fluid

Partes rectae of cortical segment 2 proximal tubules were dissected from rabbit kidneys and perfused in vitro. Ca concentrations of perfused and collected fluids were measured by continuous-flow microcolorimetry. Epithelial Ca permeability (P) was estimated from the bath-to-lumen movement of 45Ca. The transepithelial voltage (psi) and [Ca2+] difference were varied simultaneously by changing perfusate composition. Tubules that were perfused and bathed with an identical artificial ultrafiltrate of plasma displayed a lumen-negative psi, a collectate [Ca] greater than perfusate, and net Ca secretion. Tubules perfused with "late" proximal tubule fluid (high [Cl], low [HCO3], low concentrations of Na+-cotransported solutes) demonstrated a lumen-positive psi, a perfusate [Ca2+] greater than the bath, a collectate [Ca] less than perfusate, and net Ca absorption. Under each of these conditions, net Ca flux was in the direction predicted by the experimentally measured driving forces for diffusional Ca transport. Tubules that were cooled while being perfused with late proximal tubule fluid showed an increased lumen-positive psi but reduced net Ca absorption. The latter finding was consistent with reduced Ca ion diffusion related to a smaller P at the lower temperature. I conclude that Ca2+ diffusion is an important component of net Ca absorption in this segment of the nephron.

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.

Micropuncture study of the effect of ANP on the papillary collecting duct in the rat

1988 ◽  
Vol 254 (4) ◽  
pp. F477-F483 ◽  
Author(s):  
A. van de Stolpe ◽  
R. L. Jamison
Keyword(s):  
Collecting Duct ◽  
Sodium Concentration ◽  
Sodium Reabsorption ◽  
Micropuncture Study ◽  
Papillary Collecting Duct ◽  
Group 3 ◽  
Group 2 ◽  
Tubule Fluid ◽  
Group 1

Micropuncture collections were obtained from the terminal collecting duct (CD) at base and tip of the renal papilla of the rat. Group 1 was studied before and during infusion with atrial natriuretic peptide (ANP), group 2 was administered the vehicle only, and group 3 received acetazolamide to increase sodium delivery to the base to a similar extent as after ANP. ANP caused a decrease in blood pressure, a slight increase in GFR, natriuresis, and diuresis. Sodium delivery to the collecting duct at the base of the papilla increased. Between base and tip, sodium reabsorption was inhibited. Tubule fluid sodium concentration (TFNa) was increased at the base and remained high at the tip; in contrast TFNa fell between base and tip in control and acetazolamide groups. After acetazolamide, sodium reabsorption in the terminal CD was not inhibited. These results demonstrate that in vivo ANP 1) increases the delivery of sodium to the terminal CD and 2) inhibits sodium reabsorption in the terminal CD. The findings for chloride were similar to those for sodium. ANP also increased delivery of H2O, K, Ca, and Mg to the CD at the papillary base but did not significantly affect their transport by the terminal CD.

Sign in / Sign up

Export Citation Format

Share Document