Localization of diuretic effects along the loop of Henle: an in vivo microperfusion study in rats

2000 ◽  
Vol 98 (4) ◽  
pp. 481-488 ◽  
Author(s):  
R. J. UNWIN ◽  
S. J. WALTER ◽  
G. GIEBISCH ◽  
G. CAPASSO ◽  
D. G. SHIRLEY
Keyword(s):  
Carbonic Anhydrase ◽  
Loop Diuretics ◽  
Sodium Reabsorption ◽  
Thick Ascending Limb ◽  
Loop Of Henle ◽  
Low Sodium ◽  
Pars Recta ◽  
Potassium Secretion ◽  
The Individual

In order to clarify the effects on sodium reabsorption in the loop of Henle of methazolamide (a carbonic anhydrase inhibitor), chlorothiazide and the loop diuretics frusemide and bumetanide, superficial loops were perfused in vivo in anaesthetized rats and the individual diuretics were included in the perfusate. Differentiation between effects in the pars recta and in the thick ascending limb of Henle (TALH) was achieved by comparing responses to the diuretics when using a standard perfusate, designed to mimic native late proximal tubular fluid, and a low-sodium perfusate, designed to block net sodium reabsorption in the pars recta. With the standard perfusate, methazolamide caused decreases in sodium reabsorption (JNa) and water reabsorption (JV); with the low-sodium perfusate, a modest effect on JNa persisted, suggesting that carbonic anhydrase inhibition reduces sodium reabsorption in both the pars recta and the TALH. The effects of chlorothiazide were very similar to those of methazolamide with both the standard and low-sodium perfusates, suggesting that chlorothiazide also inhibits sodium reabsorption in the pars recta and TALH, perhaps through inhibition of carbonic anhydrase. With the standard perfusate, both frusemide and bumetanide produced the expected large decreases in JNa, but JV was also lowered. With the low-sodium perfusate, the inhibitory effects of the loop diuretics, particularly those of frusemide, were substantially reduced, while net potassium secretion was found. These observations indicate that a significant component of the effect of frusemide (and possibly of bumetanide) on overall sodium reabsorption is located in the pars recta, and that loop diuretics induce potassium secretion in the TALH.

Na-K-ATPase activity along the rabbit, rat, and mouse nephron

1979 ◽  
Vol 237 (2) ◽  
pp. F114-F120 ◽  
Author(s):  
A. I. Katz ◽  
A. Doucet ◽  
F. Morel
Keyword(s):  
Atpase Activity ◽  
Thick Ascending Limb ◽  
Sensitivity Limit ◽  
Henle's Loop ◽  
Collecting Tubule ◽  
Pars Recta ◽  
Hydrolysis Of ◽  
Total Enzyme

Na-K-ATPase activity along the rabbit, rat, and mouse nephron was determined with a micromethod that measures directly labeled phosphate released by the hydrolysis of [gamma-32P]ATP. Na-K-ATPase activity was highest in the rat, intermediate in the mouse, and lowest in the rabbit nephron. With the exception of rabbit cortical thick ascending limb, the enzyme profile was similar in the three species: Na-K-ATPase activity per millimeter tubule length was highest in the distal convoluted tubule and thick ascending limb of Henle's loop, intermediate in the proximal convoluted tubule, and lowest in the pars recta and collecting tubule. The enzyme was present in the thin limbs of Henle's loop, but its activity was very low and measurements were close to the sensitivity limit of the method. Both the absolute activity and the fraction of the total enzyme represented by Na-K-ATPase were severalfold higher than in kidney homogenates. Finally, the Na-K-ATPase activity measured in certain segments of the rat and rabbit nephron in this study seems sufficient to account in theory for the active component of the net sodium transport found in the corresponding region of the nephron with either in vivo or in vitro single tubule microperfusion techniques.

Aldosterone induces rapid apical translocation of ENaC in early portion of renal collecting system: possible role of SGK

2001 ◽  
Vol 280 (4) ◽  
pp. F675-F682 ◽  
Author(s):  
Johannes Loffing ◽  
Marija Zecevic ◽  
Eric Féraille ◽  
Brigitte Kaissling ◽  
Carol Asher ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Surface Expression ◽  
Apical Plasma Membrane ◽  
Sodium Reabsorption ◽  
Xenopus Laevis Oocytes ◽  
Subunit Expression ◽  
Early Portion ◽  
Potassium Secretion ◽  
Early Effects

Aldosterone controls sodium reabsorption and potassium secretion in the aldosterone-sensitive distal nephron (ASDN). Although clearance measurements have shown that aldosterone induces these transports within 30–60 min, no early effects have been demonstrated in vivo at the level of the apical epithelial sodium channel (ENaC), the main effector of this regulation. Here we show by real-time RT-PCR and immunofluorescence that an aldosterone injection in adrenalectomized rats induces α-ENaC subunit expression along the entire ASDN within 2 h, whereas β- and γ-ENaC are constitutively expressed. In the proximal ASDN portions only, ENaC is shifted toward the apical cellular pole and the apical plasma membrane within 2 and 4 h, respectively. To address the question of whether the early aldosterone-induced serum and glucocorticoid-regulated kinase (SGK) might mediate this apical shift of ENaC, we analyzed SGK induction in vivo. Two hours after aldosterone, SGK was highly induced in all segment-specific cells of the ASDN, and its level decreased thereafter. In Xenopus laevis oocytes, SGK induced ENaC activation and surface expression by a kinase activity-dependent mechanism. In conclusion, the rapid in vivo accumulation of SGK and α-ENaC after aldosterone injection takes place along the entire ASDN, whereas the translocation of α,β,γ-ENaC to the apical plasma membrane is restricted to its proximal portions. Results from oocyte experiments suggest the hypothesis that a localized activation of SGK may play a role in the mediation of ENaC translocation.

Luminal influences on potassium secretion: low sodium concentration

1984 ◽  
Vol 246 (5) ◽  
pp. F609-F619 ◽  
Author(s):  
D. W. Good ◽  
H. Velazquez ◽  
F. S. Wright
Keyword(s):  
Driving Forces ◽  
Sodium Concentration ◽  
Perfusion Fluid ◽  
Low Sodium ◽  
K Secretion ◽  
Potassium Secretion ◽  
Transepithelial Voltage ◽  
Series Of Experiments ◽  
Distal Tubules

In vivo microperfusion techniques were employed in anesthetized rats to determine whether K secretion by renal distal tubules requires the presence of Na in luminal fluid, and, if it does, in what concentration range do changes in Na concentration have the most effect. In a first series of experiments Na in perfusion fluid was replaced at constant Cl with tetramethylammonium (TMA). When the perfusion fluid Na concentration was reduced from 96 or 34 mM to 10 or 3 mM, K secretion was reduced by 50-60% and transepithelial voltage ( VTE ) was reduced by 40-60%. In a second series of experiments, in which NaCl was replaced with urea, perfusion fluid Na concentration again was reduced to 3 mM, and K secretion and VTE were reduced. In a third series of experiments, Na was replaced with rubidium. The reduced K secretion could not be explained solely by changes in electrical driving forces. The results indicate that some luminal Na (half-maximal concentration approx 10 mM) is necessary to permit K secretion to proceed at a normal rate. Considering prior measurements of luminal Na concentration in rat distal tubules, it is unlikely that changes in luminal Na concentration play an important role in regulating the rate of distal K secretion.

Effects of renal denervation on tubular sodium handling in rats with CBL-induced liver cirrhosis

2003 ◽  
Vol 284 (3) ◽  
pp. F555-F563 ◽  
Author(s):  
Thomas E. N. Jonassen ◽  
Lone Brønd ◽  
Malene Torp ◽  
Martin Græbe ◽  
Søren Nielsen ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Renal Denervation ◽  
Sodium Reabsorption ◽  
Thick Ascending Limb ◽  
Sodium Retention ◽  
Common Bile Duct Ligation ◽  
Duct Ligation ◽  
Natriuretic Effect

This study was designed to examine the effect of bilateral renal denervation (DNX) on thick ascending limb of Henle's loop (TAL) function in rats with liver cirrhosis induced by common bile duct ligation (CBL). The CBL rats had, as previously shown, sodium retention associated with hypertrophy of the inner stripe of the outer medulla (ISOM) and increased natriuretic effect of furosemide in vivo, and semiquantitative immunoblotting showed increased expression of the furosemide-sensitive Na-K-2Cl cotransporter type 2 (NKCC2) in ISOM from CBL rats. DNX significantly attenuated the sodium retention in the CBL rats, which was associated with normalization of the natriuretic effect of furosemide, as well as a significant reduction in the expression of NKCC2 in the ISOM. However, the marked hypertrophy of the ISOM found in CBL rats was not reversed by DNX. Together, these data indicate that increased renal sympathetic nerve activity known to be present in CBL rats plays a significant role in the formation of sodium retention by stimulating sodium reabsorption in the TAL via increased renal abundance of NKCC2.

ADH-like effects of calcitonin on electrolyte transport by Henle's loop of rat kidney

1984 ◽  
Vol 246 (2) ◽  
pp. F213-F220 ◽  
Author(s):  
J. M. Elalouf ◽  
N. Roinel ◽  
C. de Rouffignac
Keyword(s):  
Rat Kidney ◽  
Phosphate Transport ◽  
Hormonal Control ◽  
Electrolyte Transport ◽  
Human Calcitonin ◽  
Thick Ascending Limb ◽  
Loop Of Henle ◽  
The One ◽  
In Vivo Administration

The effects of physiological doses of human calcitonin (HCT) on renal excretion and tubular transport of water and electrolytes were investigated in hormone-deprived rats, i.e., homozygous DI Brattleboro rats with reduced levels of circulating glucagon, parathyroid hormone, and thyrocalcitonin, as these hormones are believed, together with ADH, to stimulate the same cells of the thick ascending limb. The experimental design was similar to the one used in a preceding study aimed at determining the effects of ADH in hormone-deprived rats [C. de Rouffignac et al. Am. J. Physiol. 244 (Renal Fluid Electrolyte Physiol. 13): F156-F164, 1983]. In the present experiments, HCT consistently increased the reabsorption of Mg, Ca, and K and, to a lesser extent, Na and Cl in the loop of Henle, but phosphate transport did not rise. The urinary excretion rate of Mg and Ca fell significantly. These data are very similar to the findings obtained with ADH on hormone-deprived rats. It is concluded that, in vivo, administration of HCT 1) stimulates reabsorption of Na, Cl, Mg, Ca, and K by the thick ascending limb, and 2) consistently enhances Mg and Ca reabsorption by the whole kidney by enhancing reabsorption in the loop of Henle. The similarity of the physiological responses elicited by ADH and calcitonin on the thick ascending limb supports the hypothesis of multiple hormonal control of electrolyte transport by the thick ascending limb.

Effects of diuretic drugs on Na, Cl, and K transport by rat renal distal tubule

1986 ◽  
Vol 250 (6) ◽  
pp. F1013-F1023 ◽  
Author(s):  
H. Velazquez ◽  
F. S. Wright
Keyword(s):  
Sodium Transport ◽  
Rat Kidney ◽  
Distal Tubule ◽  
Cell Types ◽  
Sodium Absorption ◽  
Thick Ascending Limb ◽  
Chloride Absorption ◽  
Diuretic Drugs ◽  
Potassium Secretion

Diuretic drugs were used to characterize mechanisms involved in transporting sodium, chloride, and potassium across the wall of surface distal tubules of the rat kidney using in vivo microperfusion techniques. Both furosemide and chlorothiazide inhibited sodium and chloride absorption but did not affect the rate of potassium secretion or the transepithelial voltage. However, chlorothiazide inhibited sodium and chloride absorption more completely than furosemide and was additive to the effect of furosemide; furosemide was ineffective if chlorothiazide was already present. In contrast to the effect of furosemide, bumetanide did not affect sodium and chloride absorption but did increase potassium secretion. Amiloride reduced sodium absorption and potassium secretion without affecting net chloride absorption. These effects were additive to those of chlorothiazide. In the loop of Henle bumetanide was more effective than furosemide in inhibiting net sodium potassium and chloride absorption. It appears that cells of the distal tubule in the rat possess an Na-Cl cotransport mechanism that differs from the Na-K-2Cl cotransport mechanism found in the thick ascending limb. Sodium transport also proceeds via a conductive pathway that is inhibited by amiloride. The two modes of sodium transport, conductive and coupled to chloride, may occur in different cell types along the distal tubule.

Effect of vasopressin on renal lithium reabsorption: a micropuncture and microperfusion study

1996 ◽  
Vol 271 (1) ◽  
pp. F223-F229 ◽  
Author(s):  
S. J. Walter ◽  
D. G. Shirley ◽  
R. J. Unwin
Keyword(s):  
Arginine Vasopressin ◽  
Concentration Ratio ◽  
Lithium Concentration ◽  
Distal Tubule ◽  
Treated Group ◽  
Thick Ascending Limb ◽  
Loop Of Henle ◽  
Brattleboro Rats ◽  
Lithium Clearance

Micropuncture techniques were used to investigate the nephron site(s) responsible for the vasopressin-induced reductions in lithium clearance and fractional lithium excretion (FELi) in anesthetized Brattleboro rats lacking endogenous vasopressin. In rats treated intravenously with the vasopressin analogue 1-desamino-8-D-arginine vasopressin (DDAVP; 40 pg/min), FELi was significantly lower than in untreated animals (0.23 +/- 0.01 vs. 0.28 +/- 0.02, P < 0.05). Free-flow micropuncture showed that fractional lithium delivery (FDLi) to late proximal convolutions was identical in the two groups, whereas at the early distal tubule both FDLi (0.28 +/- 0.02 vs. 0.33 +/- 0.01, P < 0.05) and the tubular fluid-to-plasma lithium concentration ratio (1.18 +/- 0.04 vs. 1.36 +/- 0.06, P < 0.05) were lower in the DDAVP-treated group. No differences between the groups with respect to lithium handling beyond the early distal tubule were observed. In rats subjected to in vivo microperfusion of loops of Henle, intravenous infusion of DDAVP (40 pg/min) increased fractional lithium reabsorption in the loop from 0.56 +/- 0.03 to 0.66 +/- 0.04 (P < 0.05) and from 0.39 +/- 0.02 to 0.45 +/- 0.02 (P < 0.05) at perfusion rates of 10 and 15 nl/min, respectively. We conclude that DDAVP stimulates lithium reabsorption in the loop of Henle and suggest that this results from an increased transepithelial potential difference in the thick ascending limb.

Inhibition of heme oxygenase decreases sodium and fluid absorption in the loop of Henle

2003 ◽  
Vol 285 (3) ◽  
pp. F484-F490 ◽  
Author(s):  
Tong Wang ◽  
Hyacinth Sterling ◽  
Wei A. Shao ◽  
QingShang Yan ◽  
Matthew A. Bailey ◽  
...  
Keyword(s):  
Renal Clearance ◽  
Heme Oxygenase ◽  
Rat Kidney ◽  
Thick Ascending Limb ◽  
Loop Of Henle ◽  
Fluid Absorption ◽  
High K ◽  
Normal Chow ◽  
Normal Rat

We previously demonstrated that carbon monoxide (CO) stimulates the apical 70-pS K+ channel in the thick ascending limb (TAL) of the rat kidney (Liu HJ, Mount DB, Nasjletti A, and Wang WH. J Clin Invest 103: 963-970, 1999). Because the apical K+ channel plays a key role in K+ recycling, we tested the hypothesis that heme oxygenase (HO)-dependent metabolites of heme may affect Na+ transport in the TAL. We used in vivo microperfusion to study the effect of chromium mesoporphyrin (CrMP), an inhibitor of HO, on fluid absorption ( Jv) and Na+ absorption ( JNa) in the loop of Henle and renal clearance methods to examine the effect of CrMP on renal sodium excretion. Microperfusion experiments demonstrated that addition of CrMP to the loop of Henle decreased Jv by 13% and JNa by 20% in animals on normal rat chow and caused a decrease in Jv (39%) and JNa (40%) in rats on a high-K+ (HK) diet. The effect of CrMP is the result of inhibition of HO because addition of MgPP, an analog of CrMP that does not inhibit HO, had no effect on Jv. Western blot analysis showed that HO-2 is expressed in the kidney and that the level of HO-2 was significantly elevated in animals on a HK diet. Renal clearance studies demonstrated that the infusion of CrMP increased the excretion of urinary Na+ (ENa) and volume (UV) without changes in glomerular filtration rate. The effect of CrMP on ENa and UV was larger in HK rats than those kept on normal chow. We conclude that HK intake increases HO-2 expression in the kidney and that HO-dependent metabolites of heme, presumably CO, play a significant role in the regulation of Na+ transport in the loop of Henle.

Calcium transport in the proximal convoluted tubule and loop of Henle of rats made diabetic with streptozotocin

1991 ◽  
Vol 131 (3) ◽  
pp. 373-380 ◽  
Author(s):  
H. O. Garland ◽  
P. J. Harris ◽  
T. O. Morgan
Keyword(s):  
Calcium Absorption ◽  
Diabetic Rats ◽  
Thick Ascending Limb ◽  
Loop Of Henle ◽  
Fluid Absorption ◽  
New Information ◽  
Causative Factors ◽  
Nephron Segment ◽  
Acute Changes

ABSTRACT In-vivo microperfusion was used to localize the reabsorptive defect responsible for the hypercalciuria of diabetes mellitus and to investigate possible causative factors. Unidirectional proximal calcium absorption was not significantly different in rats made diabetic with streptozotocin compared with controls, providing evidence against the involvement of this nephron segment in the phenomenon. Calcium absorption by the loop of Henle, was however, significantly (P<0·01) lower in diabetic animals (32·1 ±1·2 vs 40·4±0·6 pmol/min). Based on our knowledge of calcium movements within the loop, it is likely that the reabsorptive defect resides within the thick ascending limb. The calcium lesion was found to be independent of acute changes in intraluminal glucose concentration and could not be corrected by acute insulin treatment. The study also provides new information on the relationship between intratubular glucose and fluid movements in the rat nephron. In diabetic rats a proximal perfusate containing 30 mmol glucose/l resulted in fluid absorption comparable with that seen in control rats perfused with 5 mmol glucose/l. However, intraluminal glucose had a stimulatory effect on fluid absorption in the loop of Henle of diabetic rats (10·7 ±0·5 vs 7·9±0·4 nl/min; P<0·01). Journal of Endocrinology (1991) 131, 373–380

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