Properties of the binding sites of [3H]9‐methyl‐7‐bromoeudistomin D in bovine aortic smooth muscle microsomes

MASATOSHI ADACHI, YANO‐IL ‐I FANG, TORU YAMAKUNI, JUNICHI KOBAYASHI, YASUSHI OHIZUMI

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7 Citations (Scopus)

Abstract

Abstract— [3H]9‐Methyl‐7‐bromoeudistomin D ([3H]MBED), a powerful caffeine‐like Ca2+ releaser, binds to the caffeine binding site of terminal cisternae of skeletal muscle sarcoplasmic reticulum and activates Ca2+‐induced Ca2+ release. Properties of the binding site of [3H]MBED were investigated in aortic smooth muscle. The specific activity was higher in microsomes than in other fractions. [3H]MBED binding sites in smooth muscle microsomes were of a single class with a high affinity (KD 50 Nm), comparable with that in skeletal muscle sarcoplasmic reticulum. Caffeine competitively inhibited [3H]MBED binding, indicating MBED shares the same binding site with caffeine. Solubilization and fractionation of the microsomes gave two fractions of [3H]MBED binding activities. These results suggest that, in smooth muscle, there are multiple binding sites of [3H]MBED and caffeine, which might correspond to different pharmacological actions of caffeine on smooth muscle. Therefore, [3H]MBED, which binds to the different binding sites of caffeine, is useful as a probe for investigation of the actions of caffeine at the molecular level. 1994 Royal Pharmaceutical Society of Great Britain

Original languageEnglish
Pages (from-to)771-773
Number of pages3
JournalJournal of Pharmacy and Pharmacology
Volume46
Issue number9
DOIs
Publication statusPublished - 1994 Sep
Externally publishedYes

ASJC Scopus subject areas

  • Pharmacology
  • Pharmaceutical Science

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