Pharmacological characterization of the specific binding of [3H]ryanodine to rat brain microsomal membranes

Ildiko Zimanyi, Isaac N Pessah

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

High-affinity binding of [3H]ryanodine has been characterized in rat brain microsomal fractions. Membrane fractions from 4 brain regions (cerebral cortex, cerebellum, hippocampus and brainstem) have been isolated using sucrose density gradient purification. Sodium dodecyl sulfate polyacrylamide gel electrophoresis showed the presence of a high-molecular weight protein (Mr ∼320 kDa), similar to that of ryanodine receptor from muscle sarcoplasmic reticulum (SR). In the presence of high salt (1 M KCl), [3H]ryanodine binds to low density (0.8 M sucrose) cortical microsomal fraction with high affinity (Kd 1.5 nM), and with the highest capacity (Bmax 330 fmol/mg protein). Kinetic analysis of the binding suggests multiple available binding sites for ryanodine. Binding of ryanodine is Ca2+ dependent (ED50 1 μM) and inhibited by Mg2+ and Ruthenium red. Adenine nucleotides have a biphasic effect on the binding of [3H]ryanodine. At low Ca2+ concentration caffeine and daunorubicin enhance the binding of [3H]ryanodine. The inositol 1,4,5-trisphosphate (IP3) binding inhibitor, heparin, has no effect on ryanodine binding, and ryanodine and caffeine do not influence the binding of [3H]IP3, which is enriched in the cerebellar fractions. These data demonstrate significant quantitative differences in the pharmacology of brain and muscle receptors and raise the question as to the physiological role of ryanodine binding proteins in the central nervous system and whether it is coupled to an endoplasmatic reticulum (ER) Ca2+ release channel.

Original languageEnglish (US)
Pages (from-to)181-191
Number of pages11
JournalBrain Research
Volume561
Issue number2
DOIs
StatePublished - Oct 11 1991

Keywords

  • Brain microsome
  • Inositol 1,4,5-trisphosphate
  • Intracellular Ca
  • Ryanodine

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

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