Solutions of alkali soaps and water in fatty acids XI. Correlation between the acid sodium octanoate in the most water-rich part of the L2-phase and the acid soaps in two adjacent phases

Ekwall, Per

doi:10.1007/bf01410282

Cited by 4 publications

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References 16 publications

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“…Because the mixing and neutralization is not instantaneous, an “acid soap” mixture of water, sodium octanoate and octanoic acid is formed early in the process. The octanoic acid molecules tend to be within mixed sodium octanoate micelles and to preferentially accumulate at air‐water interfaces, or form vesicles which will hinder their diffusion, slowing their neutralization. The rapid dissolution and neutralization of the hyperpolarized octanoic acid results in a frothy white suspension containing small gas bubbles (Figure S3) which, while dissipating in less than 1 minute, imposes a delay to its infusion with the attendant polarization loss.…”

Section: Discussionmentioning

confidence: 99%

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–¹³C]octanoate

et al. 2020

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Under normal conditions, the heart mainly relies on fatty acid oxidation to meet its energy needs. Changes in myocardial fuel preference are noted in the diseased and failing heart. The magnetic resonance signal enhancement provided by spin hyperpolarization allows the metabolism of substrates labeled with carbon-13 to be followed in real time in vivo. Although the low water solubility of long-chain fatty acids abrogates their hyperpolarization by dissolution dynamic nuclear polarization, mediumchain fatty acids have sufficient solubility to be efficiently polarized and dissolved. In this study, we investigated the applicability of hyperpolarized [1-13 C]octanoate to measure myocardial medium-chain fatty acid metabolism in vivo. Scanning rats infused with a bolus of hyperpolarized [1-13 C]octanoate, the primary metabolite observed in the heart was identified as [1-13 C]acetylcarnitine. Additionally, [5-13 C] glutamate and [5-13 C]citrate could be respectively resolved in seven and five of 31 experiments, demonstrating the incorporation of oxidation products of octanoate into the tricarboxylic acid cycle. A variable drop in blood pressure was observed immediately following the bolus injection, and this drop correlated with a decrease in normalized acetylcarnitine signal (acetylcarnitine/octanoate). Increasing the delay before infusion moderated the decrease in blood pressure, which was attributed to the presence of residual gas bubbles in the octanoate solution. No significant difference in normalized acetylcarnitine signal was apparent between fed and 12-hour fasted rats. Compared with a solution in buffer, the longitudinal relaxation of [1-13 C] octanoate was accelerated~3-fold in blood and by the addition of serum albumin.These results demonstrate the potential of hyperpolarized [1-13 C]octanoate to probe myocardial medium-chain fatty acid metabolism as well as some of the limitations that may accompany its use. K E Y W O R D S13 C-MRS, beta-oxidation, cardiac, dissolution dynamic nuclear polarization, hyperpolarization, medium-chain triglyceride, serum albumin Abbreviations: BSA, bovine serum albumin; DNP, dynamic nuclear polarization; FFA, free fatty acid; IBP, invasive blood pressure; LCAD, long-chain acyl-CoA dehydrogenase; M/SCHAD, medium-and short-chain L-3-hydroxyacyl-CoA dehydrogenase; MCAD, medium-chain acyl-CoA dehydrogenase; MKAT, medium-chain 3-ketoacyl-CoA thiolase; PBS, phosphate buffered saline;RPP, rate-pressure product; SCAD, short-chain acyl-CoA dehydrogenase; TCA, tricarboxylic acid; VLCAD, very long-chain acyl-CoA dehydrogenase.

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Section: Discussionmentioning

confidence: 99%

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–¹³C]octanoate

et al. 2020

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Solutions of alkali soaps and water in fatty acids. XII. Correlations between the acid sodium octanoates in the isotropic liquidL 2-phase at water contents from 82% down to 10% and those in adjacent liquid crystalline phases

Ekwall¹

1988

Colloid & Polymer Sci

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A close connection exists between the isotropic L2-phase and the liquid crystalline lamellar D-phase. This connection is evidenced both with respect to similar compositions of their acid sodium octanoates and concerning the structure of the phases.The two-phase zone between these phases is very narrow, from 82 % down to about 55 % of water, it then widens slowly to about 40 % and thereafter very rapidly to 22 % of water; below the latter value it remains broad. The border of the L2-phase is in the whole region from 82 % to 22 % of water located at molar ratios between octanoic acid and sodium octanoate of somewhat above 2.0; the border of the D-phase lies at the same values down to a water content of 40 %. The acid octanoate 1 NaC8 : 2 HC8 : x H20 plays thus a considerable role in the phase transition all the way down to a water content of 22 %. As long as free bulk-water exists in both phases the structures in them remain alike; this similarity is greatest as long as the amount of bulk-water is so large that it suffices to form coherent domains. At contents of water below 40 %, that is after the disappearance of the bulk-water and when a decrease in the content of water begins to affect the hydration of the acid octanoates, the structural similarity between the phases disappears rapidly.

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Solutions of alkali soaps and water in fatty acids XIII. Circumstances that regulate the extension of theL 2-phase and the role of the acid-soaps rich in fatty acid for the occurrence of the phase

Ekwall¹

1988

Colloid & Polymer Sci

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A basic requirement for that type of/-2-phase which exists in the system sodium octanoate-octanoic acid-water is the formation of acid-soaps. In order for the phase to be formed at all, the temperature must lie above the melting point of the fatty acid so that a reaction in non-aqueous milieu between neutral soap and fatty acid is possible. In order to obtain the characteristic shape and complete extension of the phase in direction of high water content the temperature must be so high that also the hydrated acid-soaps occur in fluid state. On the other hand the temperature cannot be so high that the acid-soaps become unstable.At temperatures at which the phase has obtained its full extension those circumstances differs which in different regions regulate the location of the phase borders; they depend on the composition of the acid soaps and on their amounts. In that part of the phase where the molar ratio between octanoic acid and sodium octanoate lies between 2 and 3 and where one has a continuous transition from "reversed" to "normal" structure only the two acid octanoates i NaCs : 2 HC8 : x H20 and 1 NaCs : 3 HC8: x H20 occur and both are at 20 ~ in fluid state.At water contents from about 22 % to 40 % the hydrate-water molecules belonging to the first mentioned soap are capable of contributing actively to the formation of large aggregates of acid-soap, a process which however is counteracted by the inmixing of the latter acid-soap. This mixture of the two acid-soaps decides in this region where the border of the phase will lie in direction towards an increased content of sodium octanoate; the result is that in spite of the fact that the hydration is increased, the border is only slowly displaced towards a higher content of fatty acid. As soon as the hydration of the acid octanoates has been completed and the additional water occurs as unbound bulkwater, the location of the phase boundary will no longer be influenced by the water content -now it will be the amphiphilic composition of the acid-soaps that determines the location of the border and it remains at the molar ratio 2.5 between octanoic acid and sodium octanoate at water contents from about 40 % and up to 82 %.In the direction of decreasing content of neutral sodium octanoate and increased content of water the/a-phase both at the highest content of fatty acid and the highest contents of water will be in equilibrium with the water-rich Ll-phase; in the first mentioned region with the Ll-phase below the lac where at the border it is saturated with octanoic acid and in the latter region with the Ll-phase just above the lac, where the dilute sodium octanoate solution contains dissolved i NaC8 : 1 HC8 : x H20. In the large central part of the/a-phase, from about 20 % to about 86 % of water, the location of the border is dominated by the acid octanoate 1 NaC8 : 3 HC8 :x 1-120 and that makes an equilibrium with the Ll-phase impossible; instead one has an equilibrium via a two-phase zone between the amphiphile-rich region of the/a-phase and its water-rich regi...

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Solutions of alkali soaps and water in fatty acids XI. Correlation between the acid sodium octanoate in the most water-rich part of the L2-phase and the acid soaps in two adjacent phases

Cited by 4 publications

References 16 publications

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–¹³C]octanoate

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–¹³C]octanoate

Solutions of alkali soaps and water in fatty acids. XII. Correlations between the acid sodium octanoates in the isotropic liquidL 2-phase at water contents from 82% down to 10% and those in adjacent liquid crystalline phases

Solutions of alkali soaps and water in fatty acids XIII. Circumstances that regulate the extension of theL 2-phase and the role of the acid-soaps rich in fatty acid for the occurrence of the phase

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Solutions of alkali soaps and water in fatty acids XI. Correlation between the acid sodium octanoate in the most water-rich part of the L2-phase and the acid soaps in two adjacent phases

Cited by 4 publications

References 16 publications

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–13C]octanoate

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–13C]octanoate

Solutions of alkali soaps and water in fatty acids. XII. Correlations between the acid sodium octanoates in the isotropic liquidL 2-phase at water contents from 82% down to 10% and those in adjacent liquid crystalline phases

Solutions of alkali soaps and water in fatty acids XIII. Circumstances that regulate the extension of theL 2-phase and the role of the acid-soaps rich in fatty acid for the occurrence of the phase

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Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–¹³C]octanoate

Detection of myocardial medium‐chain fatty acid oxidation and tricarboxylic acid cycle activity with hyperpolarized [1–¹³C]octanoate