Content and Intracellular Distribution of Adenosine Triphosphate in Cow Adrenal Medulla1

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Abstract
Summary.: In nine experiments performed with ion exchange chromatography of the acid soluble phosphorus compounds in the cow adrenal medulla it was found that this tissue contains on the average 505 mg ATP per 100 g wet weight. There are reasons to suppose, however, that about 25 % of the ATP in the living cell have broken down before extraction could take place. The real content would thus be about 700 mg/100 g.The analyses further showed that ATP is the main phosphate ester in the medulla. AMP – if present at all – can amount to only some few per cent of the ATP quantity. The medulla may contain ADP up to 20% of the ATP amount but there are reasons to believe that the observed ADP (?) content may be only a result of ATP breakdown.As well experiments on the distribution of acid‐labile phosphates within the medullary cell as ion exchange chromatography of the phosphorus compounds in the specific granules of the medullary cell showed that ATP almost exclusively is localized to these granules containing the sympathomimetic amines. No AMP and only small amounts of ADP (?) and of inorganic P were found in granules isolated and washed in 0.3 M sucrose.The content of acid‐labile phosphorus in washed granules was on the average 74 μg/1,000 μg catechols and more than 90% of this amount can be referred to ATP. The granules can thus contain about 550 μg ATP/1,000 μg catechols (about 9% of the dry weight of the granules).The ATP in the medullary granules shows a remarkable stability. It is not released or split to any significant degree in granules suspended in 0.3 M sucrose and kept at + 4 C up to 72 hours.

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