Mikropunktionsuntersuchungen �ber die saluretische Wirkung von Hydrochlorothiazid, Acetazolamid und Furosemid

Meng, K.

doi:10.1007/bf00537125

Cited by 32 publications

(13 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The data also indicate an additional effect of chlorothiazide beyond the distal tubule puncture site. M\eng reached a similar conclusion in his study with the rat (48). Whetlher the (1rg is acting in the late distal tubule, or collecting duct, or both, remains unanswered.…”

Section: Clearance Datamentioning

confidence: 58%

See 1 more Smart Citation

Micropuncture Study of Diuretic Effects on Sodium and Calcium Reabsorption in the Dog Nephron

Edwards¹,

Baer²,

Sutton³

et al. 1973

J. Clin. Invest.

135

View full text Add to dashboard Cite

Section: Clearance Datamentioning

confidence: 58%

“…On the other hand, Heinemann, Demartini, and Laragh (19) failed to detect any change in Ca2o after chlorothiazide. Two micropuncture studies in the rat have shown an increased TF/PNa ratio in the distal tubule with hydrochlorothiazide (47,48). No data for calcium were reported.…”

Section: Clearance Datamentioning

confidence: 99%

Micropuncture Study of Diuretic Effects on Sodium and Calcium Reabsorption in the Dog Nephron

Edwards¹,

Baer²,

Sutton³

et al. 1973

J. Clin. Invest.

135

View full text Add to dashboard Cite

“…The unique ability of these agents to reduce renal calcium excretion, especially upon chronic administration, while simultaneously promoting that of sodium is a long-standing observation (1). Renal clearance (2), micropuncture (3)(4)(5)(6), and microperfusion (7,8) experiments identified the distal convoluted tubule as the nephron site at which thiazide diuretics inhibit sodium transport. Distal convoluted tubules are also the site at which thiazide diuretics stimulate calcium absorption (6).…”

Section: Introductionmentioning

confidence: 99%

Mechanism of calcium transport stimulated by chlorothiazide in mouse distal convoluted tubule cells.

Gesek¹,

Friedman²

1992

J. Clin. Invest.

172

116

View full text Add to dashboard Cite

Thiazide diuretics inhibit Na+ and stimulateCa2+ absorption in renal distal convoluted tubules. Experiments were performed on immortalized mouse distal convoluted tubule (MDCIT) cells to determine the mechanism underlying the dissociation of sodium from calcium transport and the stimulation of calcium absorption induced by thiazide diuretics. Control rates of 22Na+ uptake averaged 272±35 nmol min-' mg protein-' and were inhibited 40% by chlorothiazide (CTZ, 10'-M). Control rates of MCl-uptake averaged 340±50 nmol min' mg protein-' and were inhibited 50% by CTZ. CTZ stimulated 4"Ca2" uptake by 45% from resting levels of 2.86±0.26 nmol min' mg protein'. Bumetanide (10 -4 M) had no effect on 22Na +, -6CI -, or 45Ca 2+ uptake. Control levels of intracellular calcium activity ([Ca2+1I) averaged 91±12 nM. CTZ elicited concentration-dependent increases of ICa2+J1 to a maximum of 654±31 nM at 10-4 M. Reduction of extracellular Clor addition of NPPB abolished CTZ-induced hyperpolarization. Direct membrane hyperpolarization increased 45Ca2+ uptake whereas depolarization inhibited 45Ca2+ uptake. CTZ-stimulated 45Ca2+ uptake was inhibited by the Ca2+ channel blocker nifedipine (10-5 M). We conclude that thiazide diuretics block cellular chloride entry mediated by apical membrane NaCl cotransport. Intracellular chloride, which under control conditions is above its equilibrium value, exits the cell through NPPB-sensitive chloride channels. This decrease of intracellular chloride hyperpolarizes MDCT cells and stimulates Ca2+ entry by apical membrane, dihydropyridine-sensitive Ca2+ channels. (J. Clin. Invest. 1992. 90:429-438.) Key

show abstract

“…As a result of this dissociation, (TF/P)K+ fell significantly to less than 1.0, uncovering an uphill K+ transport system in the proximal tubule functioning independently of Na+ transport. A prior study by Watson (12) in the dog had suggested that acetazolamide caused a fall in proximal (TF/P) K+, although not to values less than 1.0, whereas Meng was unable to demonstrate any effect of acetazolamide on (TF/ P) K+ in the proximal tubule of the rat (13).…”

Section: Discussionmentioning

confidence: 88%

Sodium-Independent Active Potassium Reabsorption in Proximal Tubule of the Dog

Beck¹,

Senesky²,

Goldberg³

1973

J. Clin. Invest.

View full text Add to dashboard Cite

A B S T R A C T Prior studies of proximal tubule reabsorption have failed to distinguish conclusively between a separate active K+ transport system and K+ movement linked to Na+ reabsorption. To attempt to dissociate movement of K+ from Na+ and Ca++, recollection micropuncture experiments were performed in proximal tubules of intact and thyroparathyroidectomized (TPTX) dogs under two different conditions known to inhibit Na+ reabsorption: saline expansion to 5% body wt, and 5 mg/kg acetazolamide. A control hydropenic group was also studied. Tubular concentrations of K+, Na+, and Ca++ were measured by electron probe analysis. During initial collections, mean±i-SEM tubular fluid/plasma (TF/P)K+ was 1.07 +0.05, 1.05+0.05, and 1.00+0.03 in intact hydropenic (n = 7), saline (s = 6), and acetazolamide (i = 8) groups; fractional reabsorption (FR) of K+ in proximal tubules was 0.35, 0.39, and 0.31 respectively. After saline, (TF/P)nui n fell from 1.81 to 1.34 (P <0.01); (TF/P) K+, (TF/P) Na+, and tubular fluid/ultrafiltrate, (TF/UF)c.++ did not change, so that FR of all three ions fell proportionately. After acetazolamide, however, despite a 24% inhibition of FR of Na+ and Ca++, (TF/P)K+ fell to 0.85±0.04 (P < 0.005) so that FR of K+ was unchanged at 0.34.In three corresponding groups of TPTX dogs, similar results were obtained. Acetazolamide (n = 7) inhibited FR of Na+ and Ca++ by 41%, but (TF/P)x+ fell from 1.03±0.03 to 0.89±0.04 (P <0.005) so that FR of K+ was unchanged (0.36-0.34). A separate uphill transport system for K+ in proximal tubules is therefore unmasked by acetazolamide, a drug which selectively inhibits Na+ (and Ca++) reabsorption. Saline, on the other hand, inhibits net reabsorption of all three ions, probably by increasing passive backflux via intercellular channels.

show abstract

Mikropunktionsuntersuchungen �ber die saluretische Wirkung von Hydrochlorothiazid, Acetazolamid und Furosemid

Cited by 32 publications

References 22 publications

Micropuncture Study of Diuretic Effects on Sodium and Calcium Reabsorption in the Dog Nephron

Micropuncture Study of Diuretic Effects on Sodium and Calcium Reabsorption in the Dog Nephron

Mechanism of calcium transport stimulated by chlorothiazide in mouse distal convoluted tubule cells.

Sodium-Independent Active Potassium Reabsorption in Proximal Tubule of the Dog

Contact Info

Product

Resources

About