Effect of cocaine on the 5-HT3 receptor-mediated ion current inXenopus oocytes

P. Fan, M. Oz, L. Zhang, F. F. Weight

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14 Citations (Scopus)


The cloned 5-HT3 receptor from NCB-20 neuroblastoma cells was expressed inXenopus oocytes. In these oocytes, 5-HT, the selective 5-HT3 receptor agonists, 2-methyl-5-HT andm-chlorophenylbiguanide activated an inward current which was sensitive to the specific 5-HT3 receptor antagonist LY278584. Cocaine (0.1 to 10 μM) reversibly inhibited the current activated by 1 μM 5-HT in a concentration-dependent manner. The IC50 value is 0.7 μM and the apparent Hill coefficient is 1.55. This effect of cocaine was not dependent on membrane potential. Cocaine also produced a parallel shift of the 5-HT concentration-response curve to the right and did not reduce the maximal current induced by 5-HT. In the presence of 3 μM cocaine, the EC50 value of 5-HT was increased from 3.08 μM to 6.1 μM. Other local anesthetics such as tricaine and lidocaine also inhibited the current induced by 5-HT. These results suggest that the 5-HT3 receptors expressed inXenopus oocytes exhibit properties similar to those in sensory neurons and neuroblastoma cells and were blocked by cocaine in a competitive manner.

Original languageEnglish
Pages (from-to)181-184
Number of pages4
JournalBrain Research
Issue number2
Publication statusPublished - Mar 6 1995
Externally publishedYes


  • Cocaine
  • Competitive inhibition
  • Serotonin 5-HT receptor
  • Voltage-clamp
  • Xenopus oocyte

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


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