Porphyrin Induced Calcium Release from Skeletal Muscle Sarcoplasmic Reticulum

J. J. Abramson, S. Milne, E. Buck, Isaac N Pessah

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Micromolar concentrations of the porphyrin mesotetra(4-N-methylpyridyl)porphine tetrajodide is shown to induce rapid release of Ca2+ from skeletal muscle sarcoplasmic reticulum vesicles. Porphyrin-induced Ca2+ release is stimulated by ATP (KdATP 100 μM) and Ca2+ (KdCa = 1 μM) and is inhibited by Mg2+ (KI = 220 pM) and rutheniuni red (KI = 7 nM). The porphyrin is also shown to stimulate high affinity [3H]ryanodine binding by decreasing the dissociation constant (kd) and increasing the binding capacity (Bmax). Moreover, in the presence of Mg2+, receptor binding is sensitized to activation by Ca2+, and porphyrin-stimulated channel activity is sensitized to activation by Ca2+. These observations show that porphyrin-induced Ca2+ release is due to a direct interaction with the Ca2+ release protein from sarcoplasmic reticulum.

Original languageEnglish (US)
Pages (from-to)396-403
Number of pages8
JournalArchives of Biochemistry and Biophysics
Issue number2
StatePublished - Mar 1993

ASJC Scopus subject areas

  • Molecular Biology
  • Biophysics
  • Biochemistry


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