Clonidine-induced rhythmic activity in rabbit anococcygeus muscle

Nahid Radjaee-Behbahani, Ahmad Reza Dehpour, Emadeddin Tajkhorshid, Kolsoum Kheirollahi

Research output: Contribution to journalArticlepeer-review


1. Clonidine 0.5 mM induced an extremely regular rhythmic activity in isolated rabbit anococcygeus muscle. The movements were resistant to tetrodotoxin effect. 2. Prazosin (5×10-8M-5×10-6M) and yohimbine (1.5×10-7M-5×10-4M) showed no remarkable effect on clonidine-induced rhythmic activity. 3. The clonidine-induced contractions were dependent on extracellular calcium and could be inhibited by the omission of calcium from medium or the introduction of verapamil (IC50=1.3×10-7M) or nifedipine (IC50=7.5×10-8M). 4. Pretreatment of animals with reserpine made the preparations 2800-fold more sensitive to this action of clonidine. 5. It can be concluded from this study that clonidine is able to induce rhythmic activity in rabbit anococcygeus muscle through a mechanism that increases intracellular concentration of Ca++ via membrane calcium channels.

Original languageEnglish (US)
Pages (from-to)525-528
Number of pages4
JournalGeneral Pharmacology: Vascular System
Issue number3
StatePublished - Apr 1996
Externally publishedYes


  • Calcium
  • Calcium channel blockers
  • Rabbit anococcygeus muscle
  • Rhythmic activity

ASJC Scopus subject areas

  • Pharmacology


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