ATP modulation of L-type calcium channel currents in guinea pig outer hair cells

Chu Chen, Anastas Nenov, Charles H. Norris, Richard P. Bobbin

Research output: Contribution to journalArticlepeer-review

32 Scopus citations


Ca2+ channel currents and their modulation by adenosine 5′-triphosphate (ATP) in acutely isolated guinea pig outer hair cells (OHCs) were investigated using the whole-cell patch-clamp technique. The current-voltage (I-V) relation of OHCs indicated that the Ca2+ channel opened near -30 mV, and the current reached a maximum at + 10 and 0 mV in 20 mM Ca2+ and Ba2+ external solutions, respectively. BayK 8644 (BayK, 2 μM) caused a 3.5-fold increase in peak Ca2+ currents and shifted the I-V curves toward more negative potentials. These results suggest that the majority of Ca2+ channels in OHCs have L-type characteristics. The effects of ATP on Ca2+ channels of OHCs were heterogenous. ATP (100 μM) decreased Ca2+ channel currents by 31.7 ± 5.6% at 0 mV and shifted Ca2+ tail activation curves toward more depolarized potentials in some cells (N = 6). By contrast, in others, ATP enhanced the currents by 43.5 ± 12.5% at + 10 mV (N = 6). In the presence of BayK, however, ATP-induced inhibition or enhancement of Ca2+ channel currents was attenuated. In addition, 100 μM ATP produced little effect on Ca2+ channel currents in another subpopulation of cells (N = 12). This heterogenous neuromodulation of Ca2+ channel currents by ATP may reflect a functional diversity among OHCs.

Original languageEnglish (US)
Pages (from-to)25-33
Number of pages9
JournalHearing Research
Issue number1-2
StatePublished - Jun 1995
Externally publishedYes


  • Cochlea
  • Dihydropyridine
  • Ion channel
  • Voltage-clamp

ASJC Scopus subject areas

  • Sensory Systems


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