ArticleThe Journal of general physiology1993
Block by calcium of ATP-activated channels in pheochromocytoma cells.
Article in The Journal of general physiology, 1993. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 26 papers.
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26 citing papers in PubMed, 65 citations in OpenAlex.
- Regulation of ATP-gated P2X channels: from redox signaling to interactions with other proteins.Antioxidants & redox signaling · 2014Review
- Activation and regulation of purinergic P2X receptor channels.Pharmacological reviews · 2011Review
- Acidic amino acids impart enhanced Ca2+ permeability and flux in two members of the ATP-gated P2X receptor family.The Journal of general physiology · 2007Article
- Biophysics of P2X receptors.Pflugers Archiv : European journal of physiology · 2006Review
- P2X7 receptor stimulation of membrane internalization in a thyrocyte cell line.The Journal of membrane biology · 2005Article
- Kinetic diversity of single-channel burst openings underlying persistent Na(+) current in entorhinal cortex neurons.Biophysical journal · 2003Article
- Dehydroepiandrosterone potentiates native ionotropic ATP receptors containing the P2X2 subunit in rat sensory neurones.The Journal of physiology · 2003Article
- Bimodal action of protons on ATP currents of rat PC12 cells.The Journal of general physiology · 2003Article
- Ionic selectivity of native ATP-activated (P2X) receptor channels in dissociated neurones from rat parasympathetic ganglia.The Journal of physiology · 2001Article
- Single channel properties of P2X ATP receptors in outside-out patches from rat hippocampal granule cells.The Journal of physiology · 2000Article
- Inactivation of P2X2 purinoceptors by divalent cations.The Journal of physiology · 2000Article
- Single channel properties of P2X2 purinoceptors.The Journal of general physiology · 1999Article
- ATP stimulates sympathetic transmitter release via presynaptic P2X purinoceptors.The Journal of neuroscience : the official journal of the Society for Neuroscience · 1999Article
- Calcium permeability and block at homomeric and heteromeric P2X2 and P2X3 receptors, and P2X receptors in rat nodose neurones.The Journal of physiology · 1998Article
- ATP-activated cation currents in single guinea-pig hepatocytes.The Journal of physiology · 1998Article
- Two mechanisms for inward rectification of current flow through the purinoceptor P2X2 class of ATP-gated channels.The Journal of physiology · 1998Article
- Ca2+ signals mediated by P2X-type purinoceptors in cultured cerebellar Purkinje cells.The Journal of neuroscience : the official journal of the Society for Neuroscience · 1998Article
- Ionic permeability of, and divalent cation effects on, two ATP-gated cation channels (P2X receptors) expressed in mammalian cells.The Journal of physiology · 1996Article
- P2x-purinoceptors of myenteric neurones from the guinea-pig ileum and their unusual pharmacological properties.British journal of pharmacology · 1996Article
- Simultaneous measurement of Ca2+ influx and reversal potentials in recombinant N-methyl-D-aspartate receptor channels.Biophysical journal · 1996Article
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Authors and funding
2 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
We have investigated the effects of Ca2+ on Na+ influx through ATP-activated channels in pheochromocytoma PC12 cells using single channel current recordings. Under cell-attached patch-clamp conditions with 150 mM Na+ and 2 mM Ca2+ in the pipette, the unitary current activity showed an open level of about -4.3 pA at -150 mV. The channel opening was interrupted by flickery noise as well as occasional transition to a subconducting state of about -1.7 pA at -150 mV. The open level was decreased with increased external Ca2+, suggesting that external Ca2+ blocks Na+ permeation. We assessed the block by Ca2+ as the mean amplitude obtained with heavy filtration according to Pietrobon et al. (Pietrobon, D., B. Prod'hom, and P. Hess, 1989. J. Gen. Physiol. 94:1-21). The block was concentration dependent with a Hill coefficient of 1 and a half-maximal concentration of approximately 6 mM. A similar block was observed with other divalent cations, and the order of potency was Cd2+ > Mn2+ > Mg2+ not equal to Ca2+ > Ba2+. High Ca2+, Mg2+ and Ba2+ did not block completely, probably because they can carry current in the channel. The block by external Ca2+ did not exhibit voltage dependence between -100 and -210 mV. In the inside-out patch-clamp configuration, the amplitude of inward channel current obtained with 150 mM external Na+ was reduced by increased internal Ca2+. The reduction was observed at lower concentrations than that by external Ca2+. Internal Ba2+ and Cd2+ induced similar reduction in current amplitude. This inhibitory effect of internal Ca2+ was voltage dependent; the inhibition was relieved with hyperpolarization. The results suggest that both external and internal Ca2+ can block Na+ influx through the ATP-activated channel. A simple one-binding site model with symmetric energy barriers is not sufficient to explain the Ca2+ block from both sides.
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