Stimulation of renal phospholipid formation during potassium depletion.

1977 ◽  
Vol 233 (3) ◽  
pp. E212
Author(s):  
F G Toback ◽  
L J Havener ◽  
B H Spargo
Keyword(s):  
Potassium Depletion ◽  
Choline Uptake ◽  
Renal Cells ◽  
Renal Growth ◽  
Kennedy Pathway ◽  
Choline Incorporation ◽  
And Control ◽  
Choline Phosphoglyceride ◽  
Cortical Slices ◽  
Stimulation Of

Potassium depletion induces increased membrane phospholipid formation and renal growth in rats. To determine the mechanism by which potassium depletion augments phospholipid formation, the metabolism of radioactive choline, a precursor of choline-containing phospholipids, was studied in renal slices. Cortical and medullary tissue from potassium-depleted and control animals accumulated extracellular choline and sequentially converted it to phosphorylcholine, cytidine diphosphocholine (CDP-choline), and choline phosphoglyceride, thereby demonstrating that renal cells can utilize the Kennedy pathway for phospholipid synthesis. [14C]Choline uptake into intracellular fluid was increased in cortical slices from potassium-depleted animals. The apparent Km and Vmax of the kinase reaction which converts entering [14C]choline to [14C]phosphorylcholine were unchanged during potassium depletion. The rate of [14C]phosphorylcholine conversion to [14C]CDP-choline was also unchanged. In contrast, the Vmax of [14C]choline phosphoglyceride formation from [14C]CDP-choline was increased, whereas the apparent Km for this reaction was unchanged. These results indicate that increased renal choline phosphoglyceride formation during potassium depletion can occur via the Kennedy pathway and appears to be mediated by increases in choline uptake and the rate of CDP-choline incorporation into phospholipid, the first and last steps of the pathway.

Phosphatidylcholine metabolism during renal growth and regeneration

1984 ◽  
Vol 246 (3) ◽  
pp. F249-F259 ◽  
Author(s):  
F. G. Toback
Keyword(s):  
Compensatory Growth ◽  
Kidney Tissue ◽  
Potassium Depletion ◽  
Renal Cells ◽  
Tissue Mass ◽  
Tubular Necrosis ◽  
Kennedy Pathway ◽  
Phosphatidylcholine Biosynthesis ◽  
Phosphatidylcholine Metabolism ◽  
Stimulation Of

Phosphatidylcholine, the most abundant phospholipid in renal cellular membranes, is synthesized predominantly via the Kennedy pathway in normal and growing kidney tissue. Augmented biosynthesis of phosphatidylcholine is one of the earliest responses to growth signals in renal cells. During potassium depletion, regeneration after acute tubular necrosis, and compensatory growth after uninephrectomy increased membrane phosphatidylcholine biosynthesis precedes the appearance of new organelles and surface structures and the onset of cell division. The increment in phosphatidylcholine biosynthesis in the growing kidneys of potassium-depleted rats appears to be mediated by enhanced cellular uptake of the precursor choline and activation of the enzyme cytidine diphosphocholine:1,2-diacylglycerol cholinephosphotransferase. Specific amino acids, cations, and polyamines can modify the activity of this microsomal enzyme in normal and growing renal cells. Phospholipase A also plays a regulatory role in phosphatidylcholine metabolism because inhibition of this catabolic enzyme favors phospholipid accretion and kidney growth during potassium depletion, whereas stimulation of the enzyme leads to brisk phospholipid breakdown and a decrease in tissue mass during potassium repletion.

Additional studies on penicillin-induced stimulation of renal PAH transport

1970 ◽  
Vol 48 (8) ◽  
pp. 550-556 ◽  
Author(s):  
G. H. Hirsch ◽  
J. B. Hook
Keyword(s):  
Secretory Process ◽  
Concentrating Mechanism ◽  
Additional Step ◽  
Data Support ◽  
Penicillin Treatment ◽  
And Control ◽  
Cortical Slices ◽  
Stimulation Of

Treatment of nursing rats with penicillin significantly increased p-aminohippurate (PAH) transport in renal cortical slices from these animals, but had no effect on tetraethylammonium (TEA) transport. Addition of acetate had a similar stimulatory effect on PAH transport in renal cortical slices from both penicillin-treated and control nursing rats. Although penicillin treatment of nursing rats enhanced the accumulation of PAH by renal cortical slices, the rate of PAH entry into the tissue was not significantly increased. When pregnant rabbits were treated with penicillin during the last half of pregnancy, PAH transport was significantly increased in renal cortical slices from the treated fetuses. The effect of penicillin on PAH transport appears to be reversible since the significant increase in PAH transport observed 24 h after treating 2-week-old rabbits for 3 days was no longer observed when PAH uptake was determined 8 days after discontinuing penicillin treatment. The data support the hypothesis that the stimulatory effect of penicillin on PAH transport is due to substrate stimulation of the active concentrating mechanism mediating PAH secretion. Acetate is suggested to act at an additional step in the secretory process.

scholarly journals Antagonism of phorbol-ester-stimulated phosphatidylcholine biosynthesis by the phospholipid analogue hexadecylphosphocholine

1993 ◽  
Vol 291 (2) ◽  
pp. 561-567 ◽  
Author(s):  
T Wieder ◽  
C C Geilen ◽  
W Reutter
Keyword(s):  
Cell Lines ◽  
Hela Cells ◽  
Mdck Cells ◽  
Fold Increase ◽  
Choline Uptake ◽  
Choline Incorporation ◽  
Contrast Enhanced ◽  
Phosphatidylcholine Biosynthesis ◽  
Membrane Bound ◽  
Stimulation Of

The antagonization of phorbol 12-myristate 13-acetate (PMA)-stimulated phosphatidylcholine (PtdCho) biosynthesis by the phospholipid analogue hexadecylphosphocholine (HePC) in MDCK cells was investigated and compared with the corresponding influence in HeLa cells. In both cell lines, PMA-stimulated PtdCho biosynthesis was antagonized by 50 microM HePC. However, subsequent experiments provided evidence that PMA enhances PtdCho biosynthesis by at least two mechanisms: (i) by stimulation of choline uptake and (ii) by translocation of CTP:choline phosphate cytidylyltransferase to membranes. In MDCK cells, 5 nM PMA caused a 4-fold increase in [methyl-3H]choline incorporation into PtdCho, which was paralleled by an approx. 2-fold stimulation of choline uptake. These data indicate that choline uptake might play an important role in the regulation of PtdCho biosynthesis in this cell line, especially since we could not detect any significant increase in membrane-bound cytidyltransferase activity in PMA-treated MDCK cells. In contrast, enhanced PtdCho biosynthesis in HeLa cells is achieved by a 2-fold increase in particulate cytidylyltransferase activity after PMA stimulation. Translocation of cytidylyltransferase from the cytosol to membranes is therefore important in HeLa cells. Nevertheless, in both cell lines, the main target of HePC seems to be the translocation process. In MDCK cells, addition of 50 microM HePC decreases membrane-bound cytidylyltransferase activity by about 45%, compared with control cells and PMA-treated cells. In HeLa cells, PMA-induced translocation of cytidylyltransferase to membranes is totally abolished by HePC.

CHROMATOGRAPHY OF THE 17-KETOGENIC STEROIDS IN THE DIAGNOSIS AND CONTROL OF CONGENITAL ADRENAL HYPERPLASIA

1960 ◽  
Vol XXXIII (II) ◽  
pp. 230-250 ◽  
Author(s):  
Eileen E. Hill
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
List Type ◽  
Adrenal Hyperplasia ◽  
Normal Children ◽  
Paediatric Practice ◽  
The Mean ◽  
Cortisone Therapy ◽  
And Control ◽  
Clinical Problems ◽  
Stimulation Of

ABSTRACT A method for the fractionation of the urinary 17-ketogenic steroids with no oxygen grouping at C11 and those oxygenated at C11, is applied to the clinical problems of congenital adrenal hyperplasia. In normal children the mean ratio of the non-oxygenated to oxygenated steroids is 0.24. In childrern with congenital adrenal hyperplasia the ratio is 2.3. The reason for this difference in ratio is discussed. The changes in ratio found under stimulation of the adrenal gland with exogenous or endogenous corticotrophin and the suppression with cortisone therapy are studied. This test can be applied to isolated samples of urine, a major advantage in paediatric practice, and can be carried out in routine laboratories. It is found to be reliable in the diagnosis and sensitive in the control of congenital adrenal hyperplasia.

Somatosensory Evoked Potentials in Schizophrenia a Lateralisation Study

1990 ◽  
Vol 157 (6) ◽  
pp. 881-887 ◽  
Author(s):  
Paul Furlong ◽  
Paul Barczak ◽  
Gwilym Hayes ◽  
Graham Harding
Keyword(s):  
Index Finger ◽  
Objective Measure ◽  
Control Group ◽  
Temporal Region ◽  
Control Groups ◽  
Significant Difference ◽  
Schizophrenic Patients ◽  
Left And Right ◽  
And Control ◽  
Stimulation Of

The SSEPs obtained from 19 schizophrenics defined by RDC, DSM–III and PSE criteria Were compared with those from a control group of healthy volunteers. Previous findings of an abnormal lack of lateralising response in schizophrenic patients were not replicated. No significant difference in either amplitude or morphology between the traces obtained from the two groups were recorded. Ipsilateral and contralateral latencies for stimulation of the left and right index finger showed no significant difference in peak latency for any component between patient and control group. When mean peak-to-peak amplitudes were plotted the contralateral component was always greater in amplitude than the ipsilateral one. An objective measure of the degree of lateralisation, the percentage lateralisation quotient, showed no lateralisation differences between the patient and control groups. A case of myogenic contamination of ipsilateral components was observed calling into doubt findings where no temporal region monitoring has been performed.

scholarly journals An intermediate animal model of spinal cord stimulation

2016 ◽  
Vol 26 (2) ◽  
Author(s):  
Thomas Guiho ◽  
Christine Azevedo Coste ◽  
Claire Delleci ◽  
Jean-Patrick Chenu ◽  
Jean-Rodolphe Vignes ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Animal Model ◽  
Spinal Cord Stimulation ◽  
Spinal Cord Injuries ◽  
Large Animal Model ◽  
Large Animal ◽  
Physiological Processes ◽  
Spinal Roots ◽  
And Control ◽  
Stimulation Of

Spinal cord injuries (SCI) result in the loss of movement and sensory feedback as well as organs dysfunctions. For example, nearly all SCI subjects loose their bladder control and are prone to kidney failure if they do not proceed to intermittent (self-) catheterization. Electrical stimulation of the sacral spinal roots with an implantable neuroprosthesis is a promising approach, with commercialized products, to restore continence and control micturition. However, many persons do not ask for this intervention since a surgical deafferentation is needed and the loss of sensory functions and reflexes become serious side effects of this procedure. Recent results renewed interest in spinal cord stimulation. Stimulation of existing pre-cabled neural networks involved in physiological processes regulation is suspected to enable synergic recruitment of spinal fibers. The development of direct spinal stimulation strategies aiming at bladder and bowel functions restoration would therefore appear as a credible alternative to existent solutions. However, a lack of suitable large animal model complicates these kinds of studies. In this article, we propose a new animal model of spinal stimulation -pig- and will briefly introduce results from one first acute experimental validation session.

Enhanced coupling of adenylate cyclase to lipolysis in permeabilized adipocytes from trained rats

1991 ◽  
Vol 71 (1) ◽  
pp. 23-29 ◽  
Author(s):  
T. Izawa ◽  
T. Komabayashi ◽  
T. Mochizuki ◽  
K. Suda ◽  
M. Tsuboi
Keyword(s):  
Adenylate Cyclase ◽  
Dose Response ◽  
Response Curve ◽  
Positive Relationship ◽  
Regression Coefficient ◽  
Permeabilized Cells ◽  
Major Mechanism ◽  
The Difference ◽  
And Control ◽  
Stimulation Of

Digitonin-permeabilized adipocytes were used to study the coupling of adenylate cyclase (AC) to lipolysis in exercise-trained rats. Isoproterenol-(IPR) stimulated lipolysis in permeabilized cells was significantly greater in trained than in control rats. Under essentially identical conditions, the dose-response curve for IPR stimulation of AC activity in the absence of 3-isobutyl-1-methylxanthine was similar in trained and control rats. However, the potency of stimulation by IPR as a percentage of the basal level was greater in trained rats. AC activity and lipolysis in the presence of 3-isobutyl-1-methylxanthine were also significantly greater in trained than in control rats. Least-squares analysis by plotting the log AC vs. lipolysis values showed that the regression coefficient was about three-fold greater in trained than in control rats. The concentration of endogenous adenosine 3′,5′-cyclic monophosphate (cAMP) needed to produce a half-maximal lipolytic response was 18.58 and 10.81 pmol.min-1.10(6) cells-1 in control and trained rats, respectively. Thus a positive relationship existed between lipolysis and AC activity, with a tighter coupling in trained rats. Lipolysis in response to exogenous cAMP tended to be greater in trained than in control rats, and the difference was statistically significant for 50 microM and 10 mM cAMP. Our finding support the concept that the major mechanism of enhanced lipolysis in trained rats was an increase in the activity of enzymatic step(s) distal to cAMP.

scholarly journals Nuclear diacylglycerol is increased during cell proliferation in vivo

1993 ◽  
Vol 290 (3) ◽  
pp. 633-636 ◽  
Author(s):  
H Banfić ◽  
M Žižak ◽  
N Divecha ◽  
R F Irvine
Keyword(s):  
Cell Proliferation ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Nuclear Membrane ◽  
Cellular Proliferation ◽  
Detectable Change ◽  
Renal Growth ◽  
Kinase C ◽  
Stimulation Of

Highly purified nuclei were prepared from livers and kidneys of rats undergoing compensatory hepatic or renal growth, the former being predominantly by cellular proliferation, and the latter mostly by cellular enlargement. In liver, an increase in nuclear diacylglycerol (DAG) concentration occurred between 16 and 30 h, peaking at around 20 h. At the peak of nuclear DAG production a specific translocation of protein kinase C to the nucleus could be detected; no such changes occurred in kidney. There was no detectable change in whole-cell DAG levels in liver, and the increase in DAG was only measurable in nuclei freed of their nuclear membrane. Overall, these results suggest that there is a stimulation of intranuclear DAG production, possibly through the activation of an inositide cycle [Divecha, Banfić and Irvine (1991) EMBO J. 10, 3207-3214] during cell proliferation in vivo.

scholarly journals Acid-Base Transport and Control in Locust Hindgut: Artefacts Caused by Short-Circuit Current

1991 ◽  
Vol 155 (1) ◽  
pp. 455-467
Author(s):  
R. BRENT THOMSON ◽  
N. AUDSLEY ◽  
JOHN E. PHILLIPS
Keyword(s):  
Cyclic Amp ◽  
Acid Secretion ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Salt Bridges ◽  
Electrical Parameters ◽  
Acid Base ◽  
Before And After ◽  
And Control ◽  
Stimulation Of

The commonly used method of passing short-circuit current (Isc) across insect epithelia through Ag-AgCl electrodes, without the use of salt bridges, leads to significant OH− production at the cathode (lumen side) when high currents are applied. The alkalization of the lumen previously reported when cyclic AMP was added to short-circuited locust hindgut is a result of this phenomenon rather than cyclic-AMP-mediated stimulation of acid-base transport in the hindgut. When salt bridges are used to pass short-circuit current across locust hindgut, acid secretion (JH) into the lumen equals alkaline movement (JOH) to the haemocoel side, and JH is similar under both open- and short-circuit conditions. JH is similar (1.5 μequiv cm−2 h−1) in recta and ilea. Addition of cyclic AMP inhibits JH across the rectum by 42–66%, but has no effect on the ileum when salt bridges are used. Electrical parameters (Isc, Vt, Rt) reflecting hindgut Cl− transport (JCL) before and after stimulation with cyclic AMP are the same whether or not salt bridges are used. We found no evidence of any coupling between JCl and JH/JOH.

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