Evidence for the existence of separate transport mechanisms for choline and betaine in rat kidney

Sung, Cheng Po; Johnstone, Rose M.

doi:10.1016/0005-2736(69)90019-4

Cited by 29 publications

(7 citation statements)

References 23 publications

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“…That choline causes inhibition shows how careful one must be in assuming it is biologically inactive (see The inhibition due to lithium is presented comparing the responses during lithium infusion with those from the preceding period when the control solution was being given. also Hodgkin & Martin (1965), Lingjaerde (1969), Martin (1968, Sanford & Smyth (1969), Sung & Johnstone (1969), who have all presented evidence of biological effects of or on choline). It should be noted that the inhibition due to 2 and 26 mmol/l.…”

Section: Resultsmentioning

confidence: 97%

Some aspects of the inhibition of the action of antidiuretic hormone by lithium ions in the rat kidney and bladder of the toad Bufo marinus

Harris

Jenner

1972

British J Pharmacology

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Summary1. The effect of intravenous infusions of various ions on the antidiuretic action of antidiuretic hormone has been studied in rats. 2. Lithium (13 mmol/l.) reversibly inhibits the antidiuretic responses. Similar concentrations of potassium, rubidium, strontium, magnesium, choline and calcium do not. Lithium has a similar effect on the antidiuretic activity of oxytocin.3. The inhibition is not simply related to blood nor whole body lithium concentrations. 4. Lithium (2 mmol/l.) in contact with the serosal surface also inhibits the transport of water facilitated by either 0 5 u/i. antidiuretic hormone or 1 1 mmol/l. cyclic adenosine monophosphate in the isolated toad bladder. 5. Choline (2 mmol/l.) on the serosal surface also inhibits the transport of water facilitated by vasopressin in the toad bladder.

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Section: Resultsmentioning

confidence: 97%

Some aspects of the inhibition of the action of antidiuretic hormone by lithium ions in the rat kidney and bladder of the toad Bufo marinus

Harris

Jenner

1972

British J Pharmacology

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“…Most of the radiolabel remained in the form of choline or choline esters after incubation, therefore we are confident that we have characterized the movement of choline molecules into the epithelial cell. Hemicholinium-3 has been widely used in experiments which have examined choline uptake [6][7][8][9]. It is a specific competitive inhibitor of choline 1988 77 z 17 z z z f /////////E ., le ., ., ., z .…”

Section: Discussionmentioning

confidence: 99%

“…In order for transport to occur, an uptake mechanism would have to exist within the mammary epithelial cell (the site of milk production) which is capable of concentrative transport of choline. The uptake of choline has been investigated in a variety of tissues such as cholinergic neurons, diaphragm, liver, erythrocytes, kidney, placenta and intestine [6][7][8][9][10][11][12][13][14][15][16]. We now characterize choline uptake by isolated mammary epithelial cells from the lactating rat.…”

Section: Introductionmentioning

confidence: 99%

Uptake of choline by rat mammary-gland epithelial cells

Chao

Pomfret

Zeisel

1988

Biochemical Journal

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The neonatal mammal requires especially large amounts of choline to sustain growth. Much of this choline is derived from the newborn's only source of food, milk. The concentration of choline in rat milk [182 +/- 24 microM (S.E.M.)] was much higher than that in maternal serum (11.6 +/- 0.9 microM), suggesting that a mechanism capable of concentrating choline into milk must exist. We characterized choline uptake by mammary epithelial cells (the site of milk production) of the lactating rat. We observed two uptake processes, one saturable and obeying Michaelis-Menten kinetics, and the other non-saturable and linear. At physiological blood choline concentrations, the saturable component of choline uptake predominated. The saturable component had Kapp. = 35 +/- 16 microM, and Vmax. = 1.24 +/- 0.19 nmol/h per mg of protein. Saturable uptake of choline was inhibited by hemicholinium-3. Ca2+ was required for uptake, but Mg2+ was not. Replacement Na+ with K+, Li+ or sucrose inhibited transport. Ouabain did not inhibit choline uptake. Choline concentration in epithelial cells was 67.7 +/- 1.9 nmol/g wet wt. at the start of incubation at 37 degrees C and rose to 80.9 +/- 6.5 nmol/g wet wt. over 30 min. Much of the choline accumulated by the mammary gland (in the presence of endogenous concentrations of choline) remained in the form of choline (50 +/- 1.2%), phosphatidylcholine (12 +/- 2.3%), lysophosphatidylcholine (0.1 +/- 0.03%), betaine (7 +/- 0.3% and phosphocholine (6 +/- 0.5%). In addition, we isolated 25 +/- 1.2% of choline-derived radiolabel in an unidentified compound.

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“…[37][38] As shown in the kidney, the cellular uptake systems for betaine and choline are different. 39 This may also be true in KCs, as choline does not inhibit betaine uptake. 6 In the liver, the choline uptake systems have not been clearly characterized so far, but a saturable and a nonsaturable uptake mechanism were identified in the perfused rat liver.…”

Section: Discussionmentioning

confidence: 99%