{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,28]],"date-time":"2026-09-28T20:09:19Z","timestamp":1790626159512,"version":"4.1.0"},"reference-count":13,"publisher":"Springer Science and Business Media LLC","issue":"1","content-domain":{"domain":["link.springer.com"],"crossmark-restriction":false},"short-container-title":["Dyn Med"],"published-print":{"date-parts":[[2005,12]]},"abstract":"<jats:title>Abstract<\/jats:title>\n          <jats:sec>\n            <jats:title>Background<\/jats:title>\n            <jats:p>The increase in cytosolic free Mg<jats:sup>2+<\/jats:sup> occurring during exercise and initial recovery in human skeletal muscle is matched by a decrease in cytosolic pH as shown by <jats:italic>in vivo<\/jats:italic> phosphorus magnetic resonance spectroscopy (<jats:sup>31<\/jats:sup>P MRS). To investigate <jats:italic>in vivo<\/jats:italic> to what extent the homeostasis of intracellular free Mg<jats:sup>2+<\/jats:sup> is linked to pH in human skeletal muscle, we studied patients with metabolic myopathies due to different disorders of glycogen metabolism that share a lack of intracellular acidification during muscle exercise.<\/jats:p>\n          <\/jats:sec>\n          <jats:sec>\n            <jats:title>Methods<\/jats:title>\n            <jats:p>We assessed by <jats:sup>31<\/jats:sup>P MRS the cytosolic pH and free magnesium concentration ([Mg<jats:sup>2+<\/jats:sup>]) in calf muscle during exercise and post-exercise recovery in two patients with McArdle's disease with muscle glycogen phosphorylase deficiency (McArdle), and two brothers both affected by Tarui's disease with muscle phosphofructokinase deficiency (PFK).<\/jats:p>\n          <\/jats:sec>\n          <jats:sec>\n            <jats:title>Results<\/jats:title>\n            <jats:p>All patients displayed a lack of intracellular acidosis during muscle exercise. At rest only one PFK patient showed a [Mg<jats:sup>2+<\/jats:sup>] higher than the value found in control subjects. During exercise and recovery the McArdle patients did not show any significant change in free [Mg<jats:sup>2+<\/jats:sup>], while both PFK patients showed decreased free [Mg<jats:sup>2+<\/jats:sup>] and a remarkable accumulation of phosphomonoesters (PME). During initial recovery both McArdle patients showed a small increase in free [Mg<jats:sup>2+<\/jats:sup>] while in PFK patients the pattern of free [Mg<jats:sup>2+<\/jats:sup>] was related to the rate of PME recovery.<\/jats:p>\n          <\/jats:sec>\n          <jats:sec>\n            <jats:title>Conclusion<\/jats:title>\n            <jats:p>i) homeostasis of free [Mg<jats:sup>2+<\/jats:sup>] in human skeletal muscle is strongly linked to pH as shown by patients' [Mg<jats:sup>2+<\/jats:sup>] pattern during exercise;<\/jats:p>\n            <jats:p>ii) the pattern of [Mg<jats:sup>2+<\/jats:sup>] during exercise and post-exercise recovery in both PFK patients suggests that [Mg<jats:sup>2+<\/jats:sup>] is influenced by the accumulation of the phosphorylated monosaccharide intermediates of glycogenolysis, as shown by the increased PME peak signal.<\/jats:p>\n            <jats:p>iii) <jats:sup>31<\/jats:sup>P MRS is a suitable tool for the <jats:italic>in vivo<\/jats:italic> assessment of free cytosolic [Mg<jats:sup>2+<\/jats:sup>] in human skeletal muscle in different metabolic conditions;<\/jats:p>\n          <\/jats:sec>","DOI":"10.1186\/1476-5918-4-7","type":"journal-article","created":{"date-parts":[[2005,6,7]],"date-time":"2005-06-07T06:16:17Z","timestamp":1118124977000},"update-policy":"https:\/\/doi.org\/10.1007\/springer_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Free Mg2+ concentration in the calf muscle of glycogen phosphorylase and phosphofructokinase deficiency patients assessed in different metabolic conditions by 31P MRS"],"prefix":"10.1186","volume":"4","author":[{"given":"Emil","family":"Malucelli","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Raffaele","family":"Lodi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrea","family":"Martinuzzi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Caterina","family":"Tonon","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bruno","family":"Barbiroli","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefano","family":"Iotti","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"297","published-online":{"date-parts":[[2005,6,6]]},"reference":[{"key":"20_CR1","doi-asserted-by":"crossref","first-page":"6528","DOI":"10.1016\/S0021-9258(18)50400-2","volume":"254","author":"RWJ Lawson","year":"1979","unstructured":"Lawson RWJ, Veech RL: Effects of pH and free magnesium ion on the Keq of the creatine kinase reaction and other phosphate hydrolyses and phosphate transfer reactions. 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