Studies on the Carrier Function of Phosphatidic Acid in Sodium Transport

Hokin, Lowell E.; Hokin, Mabel R.

doi:10.1085/jgp.44.1.61

Cited by 171 publications

(19 citation statements)

References 44 publications

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“…Polyphosphoinositides are present in large amount in myelin-rich particles of guinea pig forebrain (49). It has been suggested that inositol phospholipids in membrane have important roles in the selective control of movement of ions and other solutes, packaging and translocation of macromolecules, grouping and orientation of vectorially directed enzyme systems, and transmission of extracellular information to the cell interior (50)(51)(52).…”

Section: Discussionmentioning

confidence: 99%

Composition of lipids of bovine optic nerve

Das

Steen

McCullough

et al. 1978

Lipids

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Lipids from bovine optic nerve were analyzed. The total content of 16.5% by weight included 27.2% nonpolar lipids, 26.1% glycolipids, and 46.7% phospholipids by weight. Free cholesterol was the major component of the nonpolar lipid fraction. The cerebrosides, 73.5% of total glycolipids, were separated by thin layer chromatography (TLC) into two bands (upper and lower) that were present in equal proportion. Cerebroside sulfates comprised about 27.5% of total glycolipids. Gangliosides were also detected in the glycolipid fraction. In order of predominance, choline glycerophospholipids, ethanolamine glycerophospholipids, ethanolamine plasmalogens, serine glycerophospholipids, sphingomyelins, and inositol glycerophospholipids were the major phospholipids. Palmitoyl (16:0), stearoyl (18:0), and oleoyl (18:1) groups were the major acyl groups in all neutral and phospholipid classes. However, ethanolamine glycerophospholipids, serine glycerophospholipids, and inositol glycerophospholipids contained a large percentage of 22:6 (docosahexaenoyl) group. The major alk-1-enyl groups of the plasmalogens were 16:0, 18:0, and 18:1. Steroyl (18:0), lignoceroyl (24:0), and nervonoyl (24:1) were the major acyl groups in all sphingolipids. Lower cerebroside band and cerebroside sulfates contained large amount of hydroxylignoceroyl (cerebronoyl) and hydroxynervonoyl groups.

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Section: Discussionmentioning

confidence: 99%

Composition of lipids of bovine optic nerve

Das

Steen

McCullough

et al. 1978

Lipids

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“…It seems likely that the enzymatic activity in the vesicles of endothelial cells plays a specific role in the transport function of these structures. Whether this occurs through the activation or synthesis of vesicle membrane (39,40) with the participation of an ATP/ATPase energy-producing system or through some other parameter remains to be determined. However, it may be significant that the surface membrane of endo-BIBLIOGRAPHY…”

Section: Figurementioning

confidence: 99%

The Demonstration of Enzymatic Activity in Pinocytic Vesicles of Blood Capillaries With the Electron Microscope

Marchesi

Barrnett

1963

The Journal of Cell Biology

114

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In aldehyde-fixed myocardium, enzymatic activity to nuclcotidc substrates was localized to the pinocytic vesicles of blood capillaries with thc clcctron microscope. No other structurcs of the endothelial cell showed activity under the conditions employed. Thesc findings are discussed in relation to reccnt concepts of transport across the capillary wall.A number of histochemical studies have established that the nucleotide substrates, adenosinetriphosphate (ATP), adenosinediphosphate (ADP), and adenosinemonophosphate (AMP) are hydrolyzed in the walls of the small blood vessels (1-5). These observations, made with the light microscope, demonstrate that enzymatic activity is present in or immediately adjacent to the endothelial cells.In the present work the fine structural localizations of these enzymatic activities were studied in the small blood vessels of the rat myocardium. New techniques of fixation were used and these provided adequate preservation of tissue fine structure as well as retention of enzymatic activity, As a result of these experiments the sites of these activities were localized to pinocytic vesicles. A preliminary report of these results appeared elsewhere (6). MATERIALS AND METHODSFreshly excised rat hearts were cut into small pieces (1 to 2 mm 3) and fixed in one of the following fixatives: 6.5 per cent glutaraldehyde (7) buffered to pH 7.4 with 0.1 M cacodylate, 12 per cent hydroxyadipaldehyde (7) similarly buffered, 4 per cent formalin buffered to pH 7.5 with 0.06 M phosphate and containing 7.5 per cent sucrose (8), and 1 per cent buffered osmium tetroxide~containing sucrose (9). Fixation was carried out in the cold (4°C) for varying periods of time. Two-hour fixation gave adequate preservation of structure and enzymatic activity for glutaraldehyde and hydroxyadipaldehyde and 10-hour fixation was used for formalin. It should be noted in regard to these fixatives that glutaraldehyde gave the best structural preservation as compared with the other two aldehyde fixatives and that enzymatic activity was retained by all aldehyde fixatives. Oxmium tetroxide was used as a control fixative which destroyed enzymatic activity in 10 minutes. After fixation the aldehyde-fixed tissues were washed and stored in cold 0.05 M tris or cacodylate buffer, pH 7.4, containing sucrose for periods ranging from overnight to several days. After storage they were incubated either intact or more finely diced in the standard Wachstein-Meisel adenosinetriphosphatase (ATPase) medium (10) (pH 7.1 to 7.2), containing lead nitrate, Pb(NO3)2, as the capture reagent, either at room temperature or at 10°G for periods of from 15 to 90 minutes. No significant change in pH was noted at the completion of incubation. Thin (15 /~) and thick (50 /,) frozen seetions of the same fixed material were incubated along with the blocks. At various times thin sections 547 on

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“…Yet the widespread occurrence of ACh and its associated enzymes in both neural and nonneural tissues suggests that its functions are not confined to this role. It has been proposed that ACh modifies ciliary movement in protozoans (Seaman and Houlihan, 1951) and in ciliated membranes of invertebrates (Bulbring, Burn and Shelley, 1953) and vertebrates (Kordik, Bulbring and Burn, 1952), acts as a local hormone in the control of excitability and contraction of smooth (Feldberg and Lin, 1950) and cardiac muscle (Burn and Kottegoda, 1953), is responsible for the initiation of the nerve action potential in axonal conduction (Nachmansohn, 1959), and regulates active or passive transfer of ions in the membranes of erythrocytes (Holland and Greig, 1950), frog skin (Kirschner, 1953), skeletal muscle (Van der Kloot, 1958), and avian salt glands (Hokin and Hokin, 1960). The evidence for and against these proposals has recently been summarised (Koelle, 1962b).…”

Section: VIImentioning

confidence: 99%