Guanidine sensitive transport of Na+ and K+ in mitochondria

Gómez‐Puyou, Armando; Sandoval, F.; Lotina, Blas; Gómez‐Puyou, Marietta Tuena de

doi:10.1016/0006-291x(73)90955-8

Cited by 8 publications

(5 citation statements)

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“…A competition between the action of monovalent cations and octylguanidine has been reported (12,13,24,27). A LineweaverBurk plot of 86Rb+ uptake at various concentration of 86Rb+ is shown in Figure 2.…”

Section: Resultsmentioning

confidence: 87%

“…In this work, a possible action of various alkylguanidines on the absorption of K+ by excised barley roots has been explored. The effect of alkylguanidines on K+ uptake in plants was studied because these lipophilic cations (their pKa is around 12) have been shown to inhibit numerous metal ion-dependent systems (1,2,12,13,16,23,24,(27)(28)(29) tinuously aerated distilled H20, and rinsed again 3 times with distilled H20. Seedlings were grown essentially as described by Epstein (4).…”

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confidence: 99%

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Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Lepe¹,

Avila²

1975

Plant Physiol.

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It has beeii shown that plants can accunmulate K+ through an energy-dependent process. The effect of alkylguanidines, in particular octylguanidine on the uptake of 86Rb+ by excised barley roots (Hordeum vulgare var. Apizaco LV-72), has been studied. s6Rb+ was used as tracer of K+. The uptake of 86Rb+ which is linear with time and shows saturation kinetics is inhibited by octylguanidine. Half-maximal (5,6,14,15).Little is known with respect to the molecular events that occur during K+ translocation. It has been suggested that a membranebound ATPase participates in the process (8,9,18,20,22,25) and that the uptake of K+ involves the combination of a hypothetical carrier with the ion in such a way that the intermediate ion-carrier complex that is formed on the outer part of the membrane breaks down irreversibly on the internal side of the membrane releasing the ion inside the cell (3,6,10,11). In this work, a possible action of various alkylguanidines on the absorption of K+ by excised barley roots has been explored. The effect of alkylguanidines on K+ uptake in plants was studied because these lipophilic cations (their pKa is around 12) have been shown to inhibit numerous metal ion-dependent systems (1,2,12,13,16,23,24,(27)(28)(29) tinuously aerated distilled H20, and rinsed again 3 times with distilled H20. Seedlings were grown essentially as described by Epstein (4). The seeds were placed on a plastic screen covered with cheesecloth which was supported by a 7-liter plastic tank containing 5 liters of 0.5 mm CaSO4; the corners of the cheesecloth were dipped into the solution. The tank was placed in the dark and covered with a plastic cover. The temperature was 24 C + 3 and vigorous aeration was provided.Roots from 6-day-old seedlings were used for the absorption experiments. The roots were cut in 2-cm segments (the 3-cm basal portions and 5-cm apical portions of the roots were discarded) and washed 3 times with ice-cold distilled H20. The tissue prepared in this form is a highly homogeneous material. Batches of 16 segments were maintained in distilled H20 until the experiment was initiated. The uptake experiments were carried out by incubating barley roots in 4 ml of a mixture that contained 20 mm maleic buffer (pH 6), 0.05 mm CaSO4, and different concentrations of the indicated alkylguanidines and RbCl according to the experiment. Experiments on the ion absorption by excised tissues of higher plants have shown that potassium and rubidium behave virtually as isotopes of the same element (21). Therefore, l6Rb+ was used as a radioactive analog of K+. The incubation medium was maintained at 30 C and continuously shaken in a Dubnoff incubator. The solution was equilibrated for a 10-min period prior to the addition of the roots. At the times indicated in the respective figures (see under "Results"), the solution was decanted, and the roots were rinsed for 30 sec with a mixture of 30 ml of ice-cold 0.5 mm CaSO4 and 5 mm RbCl to eliminate adsorbed lGRb+. Subsequently the roots were washed for 30 min in 15 ml...

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Section: Resultsmentioning

confidence: 87%

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confidence: 99%

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Lepe¹,

Avila²

1975

Plant Physiol.

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“…For mitochondrial ATPase measurements, the mitochondria were further purified as follows. The final mitochondrial pellet obtained from the second 8,000g centrifugation was suspended in 2 ml of 15% sucrose, 1 mM MgSO4, and I mm DTT and layered into a 36-ml discontinuous gradient consisting of 9 (8).…”

Section: Methodsmentioning

confidence: 99%

“…The mode of action of the substituted guanidines is uncertain, but they are known to interfere with mitochondrial metabolism including ATP formation (2-5, 13, 14, 17, 19) and the energized transport of Na+ and K+ (9). They also competitively inhibit K+ transport in yeast (18) and block the Na+ channel in nerve and muscle membranes (10).…”

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Alkylguanidine Inhibition of Ion Absorption in Oat Roots

Gomez-Lepe¹,

Hodges²

1978

Plant Physiol.

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The effect of various alkylguanidines on ion absorption and energy metabolism in oat (Avena sadva cv. Goodfileld) roots has been investigated. Of several alkylguanidines tested, octylguanidine was the most effective inhibitor of both K+ and Clr absorption by excised roots. At 225 JM octylguanidine, the transport of both ions was inhibited within 60 seconds and to a similar extent. Octylguanidine inhibited mitochondrial oxidative phosphorylation and mitochondrial adenosine 5'-triphosphatase (ATPase Inhibition by octylguanidine of K+ and Cl-absorption by excised oat roots may be due to an inhibition of either the plasma membrane ATPase or mitochondrial oxidative phosphorylation. The isolated plasma membrane did not appear to be permeable to octylguanidine since the plasma membrane ATPase was inhibited only after treating the membrane with Triton. This result indicates that the primary site of action of octylguanidine in excised root is more likely to be the plasma membrane ATPase than mitochondrial oxidative phosphorylation.A variety of guanidine derivatives have been used clinically for the treatment of several human abnormalities including diabetes, malaria, botulism, and hypertension. The mode of action of the substituted guanidines is uncertain, but they are known to interfere with mitochondrial metabolism including ATP formation (2-5, 13, 14, 17, 19) and the energized transport of Na+ and K+ (9). They also competitively inhibit K+ transport in yeast (18) and block the Na+ channel in nerve and muscle membranes (10). K+ absorption by roots of barley was inhibited by octylguanidine (8).Guanidine is a strong organic base with a pKa of about 12.5.At physiologic pH, all but a small fraction of the guanidine molecules exist as positively charged species, i.e. L NH NH2 Alkylation of guanidine increases its inhibitory effect on energy transfer reactions of mitochondria (19). Since the alkyl side chain renders guanidine more lipophyllic, positively charged alkylguanidines may interact with the phospholipids of membranes (21, 22). However, a negative site or region of a protein, buried within the lipid, could be the target for the alkylguanidines (17).The basis for alkylguanidine inhibition of K+ absorption in plants has been investigated. In particular, we examined the effect of octylguanidine on energy transfer reactions of mitochondria and the plasma membrane of oat roots. MATERIALS AND METHODSAbsorption Experiments. Roots from dark-grown 5-day old oat seedlings (A vena sativa L. cv. Goodfield) were used. Seeds were placed in rows between layers of cheesecloth and grown hydroponically over I mm CaSO4 for 5 days as described (12). Absorption of K+ and CF-were determined with 86Rb and 36C1, respectively (I 1). Seedlings were removed from the cheesecloth screen and their roots cut into 1-cm segments. Segments from three roots (90-100 mg) were incubated in 10 ml of I mm KCI containing 8'Rb or 36C1 and different concentrations of alkylguanidines. The pH was adjusted with KOH or HCI. The experiments were conducte...

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“…In mitochondria, octylguanidine inhibits oxidative phosphorylation by blocking sodium-stimulated uptake of oxygen and sodium-stimulated release of potassium (GOMEZ-PUYOU et al 1973). In mitochondria, octylguanidine inhibits oxidative phosphorylation by blocking sodium-stimulated uptake of oxygen and sodium-stimulated release of potassium (GOMEZ-PUYOU et al 1973).…”

Section: G Clinical Nonvirologic Studiesmentioning

confidence: 99%

Chemotherapy of Viral Infections

Jones¹

1982

Handbook of Experimental Pharmacology

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Guanidine sensitive transport of Na+ and K+ in mitochondria

Cited by 8 publications

References 10 publications

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Alkylguanidine Inhibition of Ion Absorption in Oat Roots

Chemotherapy of Viral Infections

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Guanidine sensitive transport of Na+ and K+ in mitochondria

Cited by 8 publications

References 10 publications

Alkylguanidines as Inhibitors of K+ Transport in Isolated Barley Roots

Alkylguanidines as Inhibitors of K+ Transport in Isolated Barley Roots

Alkylguanidine Inhibition of Ion Absorption in Oat Roots

Chemotherapy of Viral Infections

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Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots

Alkylguanidines as Inhibitors of K⁺ Transport in Isolated Barley Roots