Perfusion-secretion relationships in the isolated elasmobranch rectal gland

Perfusion and sodium secretion parameters were measured in the isolated rectal gland of Scyliorhinus canicula L. perfused at in vivo pressures, and the effect of stimulation of secretory activity by cyclic AMP and theophylline on these parameters was determined. Stimulation resulted in large increases in secretion flow rate, percentage extraction of sodium from the perfusing fluid, and arteriovenous sodium concentration difference, but did not affect perfusion flow rate or the sodium concentration of the secreted fluid. Reduction of perfusion flow rate to values below 65% of the control level, achieved by reducing perfusion pressure, produced a marked decline in sodium secretion--a process accompanied by increases in the percentage extraction of sodium and arteriovenous concentration difference of sodium, but again without any change in the sodium concentration of the secreted fluid. The in vivo consequences of these findings are discussed with reference to related findings for the avian nasal salt gland. The normal rate of secretion, its sodium concentration, and the nature of the dependence of secretion rate on perfusion flow below certain levels, were essentially unaffected by a reduction in the availability of oxygen to the gland by approximately 80%. It is concluded that the observed relationship between perfusion flow and sodium secretion rate in the stimulated gland is not related to oxygen availability, and hence that the primary underlying function of the synchronized secretion-related vasodilation seen in the gland is not to increase the supply of oxygen to the stimulated secretory tissue. We discuss possible reasons why this erroneous conclusion has been reached by other workers.

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Microdialysis in human skeletal muscle: effects of adding a colloid to the perfusate

Journal of Applied Physiology ◽

10.1152/jappl.2002.92.1.385 ◽

2002 ◽

Vol 92 (1) ◽

pp. 385-393 ◽

Cited By ~ 29

Author(s):

K. Hamrin ◽

H. Rosdahl ◽

U. Ungerstedt ◽

J. Henriksson

Keyword(s):

Hydrostatic Pressure ◽

Flow Rate ◽

Glucose Concentration ◽

Fluid Loss ◽

Dialysis Membrane ◽

Perfusion Flow ◽

Perfusion Flow Rate ◽

Perfused Catheters

Microdialysis catheters (CMA-60 with a polyamide dialysis membrane; 20,000-molecular wt cutoff) were either immersed in an external medium or were inserted in the quadriceps femoris muscle of healthy subjects, using perfusate with or without dextran 70. Varying the position of the outflow tubing induced changes in hydrostatic pressure. The sample volumes were significantly smaller in catheters perfused without a colloid compared with those perfused with a colloid [11–50% (in vitro) and 8–59% (in vivo) lower than in colloid-perfused catheters with the same position of the outflow tubing]. The sample volumes were also significantly smaller when the dialysis membrane was influenced by maximal hydrostatic pressure (above position) compared with minimal hydrostatic pressure (below position) [7–38% (in vitro) and 3–46% (in vivo) lower than in catheters in the below position with the same perfusion fluid]. In vivo, glucose concentration at a perfusion flow rate of 0.33 μl/min was higher when the catheters were perfused without a colloid [18–28% higher than in colloid-perfused catheters with the same position of the outflow tubing ( P < 0.001)] than with a colloid. A corresponding difference also tended to occur with lactate, glycerol, and urea. At 0.16 μl/min, the glucose concentration was the same irrespective of whether fluid loss had been counteracted by colloid inclusion or by lowering of outlet tubing. The mechanism behind the observed concentration difference is thought to be a higher effective perfusion flow rate when fluid loss is prevented at low-perfusion flows. This study shows that fluid imbalances can have important implications for microdialysis results at low-perfusion flow rates.

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Primary role of volume expansion in stimulation of rectal gland function

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1985.248.5.r638 ◽

1985 ◽

Vol 248 (5) ◽

pp. R638-R640 ◽

Cited By ~ 1

Author(s):

R. Solomon ◽

M. Taylor ◽

S. Sheth ◽

P. Silva ◽

F. H. Epstein

Keyword(s):

Plasma Volume ◽

Plasma Osmolality ◽

Sodium Concentration ◽

Chloride Secretion ◽

Ringer Solution ◽

Rectal Gland ◽

Primary Role ◽

Fourfold Increase ◽

Gland Function

Chloride secretion by the in vivo rectal gland of the shark is stimulated by the intravascular infusion of salt solutions of varying osmolar and sodium concentration. In a cross-perfused and denervated rectal gland, the infusion of a small amount of a hypertonic salt solution raises plasma osmolality but does not increase plasma volume in the donor fish. Under these conditions, rectal gland chloride secretion is not stimulated. A subsequent infusion of isotonic shark Ringer solution increases plasma volume 50%, decreases plasma osmolality, and produces a fourfold increase in chloride secretion and a threefold decrease in vascular resistance within the gland. Both the vasodilatory and secretory responses also follow the infusion of a hypotonic shark Ringer solution. The data further support the hypothesis that the rectal gland of the shark is involved in the regulation of intravascular volume rather than in osmoregulation.

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Effect of arginine depletion on glomerular and tubular kidney function: studies in isolated perfused rat kidneys

AJP Renal Physiology ◽

10.1152/ajprenal.1991.261.5.f779 ◽

1991 ◽

Vol 261 (5) ◽

pp. F779-F786 ◽

Cited By ~ 6

Author(s):

J. Radermacher ◽

B. Klanke ◽

S. Kastner ◽

G. Haake ◽

H. J. Schurek ◽

...

Keyword(s):

Flow Rate ◽

Specific Inhibitor ◽

Free Water ◽

Renal Perfusion ◽

Physiological Concentration ◽

Perfusion Flow ◽

Glucose Reabsorption ◽

Glomerular Hemodynamics ◽

Perfusion Flow Rate ◽

Rat Kidneys

The effect of L-Arg depletion on glomerular hemodynamics and tubular function of isolated rat kidneys perfused with a medium containing 21 amino acids has been studied. A cyclooxygenase inhibitor was added throughout for blockade of prostaglandin synthesis. Arg depletion caused significant (approximately 30%) reductions in renal perfusion flow rate (PFR, 13.9 +/- 1.2 vs. 19.8 +/- 0.6 ml.min-1.g (kidney wt-1), glomerular filtration rate (GFR, 598 +/- 79 vs. 924 +/- 42 microliters.min-1.g kidney wt-1), and urine flow rate (139 +/- 38 vs. 192 +/- 13 microliters.min-1.g kidney wt-1) compared with control kidneys, which were perfused with a physiological concentration of Arg (200 microM). Filtration fraction (FF) increased with Arg depletion (5.1 +/- 0.4 vs. 4.4 +/- 0.4%). Arg-depleted kidneys had a lower absolute sodium (TNa, 75.7 +/- 8.8 vs. 107.9 +/- 6.0 mumol.min-1.g kidney wt-1) and glucose reabsorption (T glucose, 3.7 +/- 0.6 vs. 5.6 +/- 0.5 mumol.min-1.g kidney wt-1), corresponding to a lower sodium and glucose filtration. Potassium handling and reabsorption of free water were not changed. Oxygen consumption (QO2) was lower in Arg-depleted kidneys (4.6 +/- 0.3 vs. 5.5 +/- 0.5 mumol.min-1.g kidney wt-1). The effects of Arg depletion were completely reversed by the addition of Arg (1 mM) at 120 min and partly reversed by the addition of citrulline (1 mM). Ornithine depletion or addition had no effect on PFR, GFR, FF, TNa, T glucose, and QO2. N omega-methyl-L-arginine, a specific inhibitor of nitric oxide endothelium-derived relaxing factor, produced the same effect as Arg depletion.(ABSTRACT TRUNCATED AT 250 WORDS)

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Indocyanine green R15 ratio depends directly on liver perfusion flow rate

Journal of Hepato-Biliary-Pancreatic Sciences ◽

10.1007/s00534-009-0160-0 ◽

2009 ◽

Vol 17 (2) ◽

pp. 180-185 ◽

Cited By ~ 15

Author(s):

Martin W. W. Janssen ◽

Karl T. Druckrey-Fiskaaen ◽

Leyla Omidi ◽

Grzegorz Sliwinski ◽

Christine Thiele ◽

...

Keyword(s):

Indocyanine Green ◽

Flow Rate ◽

Liver Perfusion ◽

Perfusion Flow ◽

Perfusion Flow Rate

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Effect of Perfusion Flow Rate on the Tissue Uptake of Solutes After Dermal Application Using the Rat Isolated Perfused Hindlimb Preparation

Journal of Pharmacy and Pharmacology ◽

10.1111/j.2042-7158.1994.tb03741.x ◽

1994 ◽

Vol 46 (10) ◽

pp. 844-850 ◽

Cited By ~ 11

Author(s):

SHEREE E. CROSS ◽

ZHENYU WU ◽

MICHAEL S. ROBERTS

Keyword(s):

Flow Rate ◽

Tissue Uptake ◽

Perfusion Flow ◽

Perfusion Flow Rate ◽

Dermal Application

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Contributions of Liver Perfusion Flow Rate and Enzyme Inhibition to Altered Verapamil Clearance With Halothane

Anesthesia & Analgesia ◽

10.1213/00000539-199011000-00005 ◽

1990 ◽

Vol 71 (5) ◽

pp. 484???488 ◽

Cited By ~ 8

Author(s):

Edward J. Frink ◽

Thomas H. Kramer ◽

Susan M. Banchy ◽

Burnell R. Brown

Keyword(s):

Enzyme Inhibition ◽

Flow Rate ◽

Liver Perfusion ◽

Perfusion Flow ◽

Perfusion Flow Rate

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Luminal influences on potassium secretion: sodium concentration and fluid flow rate

AJP Renal Physiology ◽

10.1152/ajprenal.1979.236.2.f192 ◽

1979 ◽

Vol 236 (2) ◽

pp. F192-F205 ◽

Cited By ~ 37

Author(s):

D. W. Good ◽

F. S. Wright

Keyword(s):

Fluid Flow ◽

Flow Rate ◽

Distal Tubule ◽

Sodium Concentration ◽

Fluid Flow Rate ◽

Physiological Range ◽

Luminal Flow ◽

Potassium Secretion ◽

K Concentration

Two methods of in vivo continuous microperfusion were used to evaluate separately luminal sodium concentration and fluid flow rate as factors regulating potassium secretion by the renal distal tubule of the rat. Emphasis was placed on evaluating changes in sodium concentration (43-97 mM) and flow rate (4-27 nl/min) within the physiological range. Absolute rates of Na, K, Cl, and H2O transport were measured. Results showed that increasing early distal flow rate without increasing early distal Na concentration significantly increased the absolute rate of potassium secretion by the distal tubule. In contrast, increasing early distal Na concentration, distal Na delivery, and distal Na absorption did not affect potassium secretion if flow rate was not changed. Further studies showed that reducing early distal Na concentration below the physiological range (to 15 mM) caused the direction of net sodium transport to be reversed but did not significantly reduce potassium secretion. Increasing early distal K concentration (to 34 mM) caused the direction of net potassium transport to be reversed. The rate of potassium secretion appears to depend in part on the luminal potassium concentration. Increases in luminal flow rate may increase the rate of potassium secretion by lowering the luminal K concentration.

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