Rat chromaffin cells lack P2X receptors while those of the guinea-pig express a P2X receptor with novel pharmacology

Br J Pharmacol. 1999 Sep;128(1):61-8. doi: 10.1038/sj.bjp.0702790.


1. Whole-cell patch-clamp recording was used to determine the functional expression and pharmacological properties of P2X receptors in chromaffin cells dissociated from adrenal medullae of rats and guinea-pigs. 2. In rat chromaffin cells maintained in culture for 1 - 7 days, ATP and UTP failed to evoke any detectable response. 3. Guinea-pig chromaffin cells responded to ATP (100 microM) with a rapidly activating inward current. The amplitude of the response to ATP increased over the period cells were maintained in culture and so did the number of cells giving a detectable response, with 69% of cells responding after >/=4 days of culture. 4. The response to ATP desensitized slowly, and had a reversal potential of 2.5 mV. The EC50 for ATP was 43 microM. The potency order for ATP analogues was 2-MeSATP>ATP>ADP. Adenosine, UTP and alpha,beta-meATP were inactive. 5. Suramin (100 microM) and Cibacron blue (50 microM) inhibited the ATP (100 microM)-activated current by 51 and 47%, respectively. PPADS antagonized the response to ATP (100 microM) with an IC50 of 3.2 microM. 6. The ATP concentration-response curve shifted to the left at pH 6.8 (EC50, 19 microM) and right at pH 8.0 (EC50, 96 microM), without changing the maximal response. Zn2+ inhibited the response to ATP (100 microM) with an IC50 of 48 microM. 7. This study indicates that expression of ATP-gated cation channels in chromaffin cells is species dependent. The P2X receptors in guinea-pig chromaffin cells show many characteristics of the P2X2 receptor subtype.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / analogs & derivatives
  • Adenosine Triphosphate / antagonists & inhibitors
  • Adenosine Triphosphate / pharmacology
  • Adrenal Medulla / cytology
  • Animals
  • Cells, Cultured
  • Chromaffin Cells / cytology
  • Chromaffin Cells / drug effects
  • Chromaffin Cells / metabolism*
  • Dimethylphenylpiperazinium Iodide / pharmacology
  • Electric Conductivity
  • Guinea Pigs
  • Hydrogen-Ion Concentration
  • Inhibitory Concentration 50
  • Male
  • Membrane Potentials / drug effects
  • Nicotinic Agonists / pharmacology
  • Purinergic P2 Receptor Agonists
  • Purinergic P2 Receptor Antagonists
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Purinergic P2 / metabolism*
  • Receptors, Purinergic P2X2
  • Species Specificity
  • Uridine Triphosphate / pharmacology
  • Zinc / pharmacology


  • Nicotinic Agonists
  • P2rx2 protein, rat
  • Purinergic P2 Receptor Agonists
  • Purinergic P2 Receptor Antagonists
  • Receptors, Purinergic P2
  • Receptors, Purinergic P2X2
  • Dimethylphenylpiperazinium Iodide
  • Adenosine Triphosphate
  • Zinc
  • Uridine Triphosphate