A novel receptor-operated Ca2+-permeable channel activated by ATP in smooth muscle

Nature. 1987 Jul;328(6127):275-8. doi: 10.1038/328275a0.


Receptor-operated Ca2+ entry has been proposed as a signalling mechanism in many cells. Receptor-operated Ca2+ channels (ROCs) were first postulated in smooth muscle by Bolton, van Breemen and Somlyo and Somlyo, but recordings of directly ligand-gated Ca2+ current are lacking. Here we describe receptor-operated Ca2+ current evoked in arterial smooth muscle cells by ATP, a sympathetic neurotransmitter. ATP activates channels with approximately 3:1 selectivity for Ca2+ over Na+ at near-physiological concentrations and with a unitary conductance of approximately 5 pS in 110 mM Ca2+ or Ba2+. The channels can be opened even at very negative potentials and resist inhibition by cadmium or nifedipine, unlike voltage-gated Ca2+ channels; they are not blocked by Mg2+, unlike NMDA (N-methyl-D-aspartate)-activated channels; they are directly activated by ligand, without involvement of readily diffusible second messengers, unlike cation channels in neutrophils and T lymphocytes. Thus, the ATP-activated channels provide a distinct mechanism for excitatory synaptic current and Ca2+ entry in smooth muscle.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / physiology*
  • Animals
  • Cadmium / pharmacology
  • Calcium / physiology*
  • Electric Conductivity
  • Ion Channels / physiology*
  • Membrane Potentials
  • Muscle, Smooth, Vascular / physiology*
  • Nifedipine / pharmacology
  • Rabbits
  • Receptors, Cell Surface / physiology*
  • Synapses / physiology


  • Ion Channels
  • Receptors, Cell Surface
  • Cadmium
  • Adenosine Triphosphate
  • Nifedipine
  • Calcium