Angiotensin II as a Mediator of Renal Tubular Transport

2001 ◽  
pp. 47-62 ◽  
Author(s):  
C.R.J. Kennedy ◽  
K.D. Burns
Keyword(s):  
Angiotensin Ii ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

HOMEOSTATIC ADJUSTMENT IN THE RENAL TUBULAR TRANSPORT OF INORGANIC PHOSPHATE IN THE DOG

1955 ◽  
Vol 33 (1) ◽  
pp. 638-650 ◽  
Author(s):  
James G. Foulks
Keyword(s):  
Inorganic Phosphate ◽  
Renal Tubule ◽  
Phosphate Transport ◽  
Sodium Sulphate ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Transport Of Inorganic Phosphate ◽  
Renal Tubular ◽  
Filtered Load

By means of the infusion of small amounts of sodium sulphate it has been possible to elevate the filtered load of inorganic phosphate to the renal tubule in fasted dogs without the administration of exogenous phosphate. Under these circumstances, the reabsorption of phosphate remains virtually complete, even when filtered loads are reached which result in a substantial phosphaturia when phosphate has been administered. By comparing phosphate reabsorption and excretion in fasted animals, and in animals at various intervals after feeding, the existence of homeostatic adjustments in the renal tubular transport of inorganic phosphate has been demonstrated. The available evidence suggests that the intracellular disposition of phosphate itself may be an important factor in determining the rate of renal tubular phosphate transport at filtered loads in the physiological range. The limitations of the determination of the phosphate "Tm" as a device for studying homeostatic processes have been discussed.

AVP-stimulated nucleotide secretion in perfused mouse medullary thick ascending limb and cortical collecting duct

2009 ◽  
Vol 297 (2) ◽  
pp. F341-F349 ◽  
Author(s):  
Elvin Odgaard ◽  
Helle A. Praetorius ◽  
Jens Leipziger
Keyword(s):  
Collecting Duct ◽  
Tubular Secretion ◽  
Hormonal Control ◽  
Similar Response ◽  
Thick Ascending Limb ◽  
Cortical Collecting Duct ◽  
Medullary Thick Ascending Limb ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

Extracellular nucleotides are local, short-lived signaling molecules that inhibit renal tubular transport via both luminal and basolateral P2 receptors. Apparently, the renal epithelium itself is able to release nucleotides. The mechanism and circumstances under which nucleotide release is stimulated remain elusive. Here, we investigate the phenomenon of nucleotide secretion in intact, perfused mouse medullary thick ascending limb (mTAL) and cortical collecting duct (CCD). The nucleotide secretion was monitored by a biosensor adapted to register nucleotides in the tubular outflow. Intracellular Ca2+ concentration ([Ca2+]i) was measured simultaneously in the biosensor cells and the renal tubule with fluo 4. We were able to identify spontaneous tubular nucleotide secretion in resting perfused mTAL. In this preparation, 10 nM AVP and 1-desamino-8-d-arginine vasopressin (dDAVP) induced robust [Ca2+]i oscillations, whereas AVP in the CCD induced large, slow, and transient [Ca2+]i elevations. Importantly, we identify that AVP/dDAVP triggers tubular secretion of nucleotides in the mTAL. After addition of AVP/dDAVP, the biosensor registered bursts of nucleotides in the tubular perfusate, corresponding to a tubular nucleotide concentration of ∼0.2–0.3 μM. A very similar response was observed after AVP stimulation of CCDs. Thus AVP stimulated tubular secretion of nucleotides in a burst-like pattern with peak tubular nucleotide concentrations in the low-micromolar range. We speculate that local nucleotide signaling is an intrinsic feedback element of hormonal control of renal tubular transport.

HOMEOSTATIC ADJUSTMENT IN THE RENAL TUBULAR TRANSPORT OF INORGANIC PHOSPHATE IN THE DOG

1955 ◽  
Vol 33 (4) ◽  
pp. 638-650 ◽  
Author(s):  
James G. Foulks
Keyword(s):  
Inorganic Phosphate ◽  
Renal Tubule ◽  
Phosphate Transport ◽  
Sodium Sulphate ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Transport Of Inorganic Phosphate ◽  
Renal Tubular ◽  
Filtered Load

By means of the infusion of small amounts of sodium sulphate it has been possible to elevate the filtered load of inorganic phosphate to the renal tubule in fasted dogs without the administration of exogenous phosphate. Under these circumstances, the reabsorption of phosphate remains virtually complete, even when filtered loads are reached which result in a substantial phosphaturia when phosphate has been administered. By comparing phosphate reabsorption and excretion in fasted animals, and in animals at various intervals after feeding, the existence of homeostatic adjustments in the renal tubular transport of inorganic phosphate has been demonstrated. The available evidence suggests that the intracellular disposition of phosphate itself may be an important factor in determining the rate of renal tubular phosphate transport at filtered loads in the physiological range. The limitations of the determination of the phosphate "Tm" as a device for studying homeostatic processes have been discussed.

Renal tubular transport of Diodrast-I131 and PAH in Necturus: evidence for simultaneous reabsorption and secretion

1959 ◽  
Vol 196 (5) ◽  
pp. 1141-1149 ◽  
Author(s):  
William B. Kinter
Keyword(s):  
Seasonal Variation ◽  
Carboxylic Acid ◽  
Creatinine Clearance ◽  
Plasma Concentrations ◽  
High Plasma ◽  
Arterial Blood ◽  
Tubular Transport ◽  
Renal Tubular Transport ◽  
Renal Tubular

Renal plasma clearances were determined in pithed Necturi from samples of cloacal urine and branchial arterial blood. Simultaneous clearance of creatinine and inulin carboxylic acid-C14 corresponded closely. Diodrast-I131 and/or para-aminohippurate (PAH) clearances were less than simultaneous creatinine clearances in about 80% of the Necturi. At low plasma concentrations of Diodrast and/or PAH, Diodrast/ creatinine and/or PAH/creatinine clearance ratios were independent of concentration and exhibited a seasonal variation, approximating 0.2 in ‘winter’ and 0.5 in ‘summer.’ In a random 20% of the animals, however, ratios were greater than unity, approximating 2.0. In both groups of animals the ratios generally approached unity at high plasma concentrations. However, under the conditions of high PAH and low Diodrast concentrations in the group with initial ratios less than unity, the Diodrast ratio approximated 2.0. These data are interpreted as evidence that in Necturus kidney over-all tubular transport of Diodrast and PAH is the net result of simultaneous reabsorption out of and secretion into tubular urine.

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