Cyclic nucleotide-gated channels in identified human olfactory receptor neurons.
Patch-clamp recordings revealed the presence of a non-desensitizing cyclic nucleotide-gated channel on human olfactory receptor neurons and a fast-desensitizing non-specific cation channel activated by nucleotides on human supporting cells. Cyclic nucleotide-gated channels on olfactory receptor neurons showed selective channel activation by cAMP (K1/2 = 5 microM) and cGMP (K1/2 = 2 microM), a unitary conductance of approximately 20 pS, a reversal potential of single-channel currents close to 0 mV, a linear current-voltage relationship over the range of -80 to 80 mV and a strong extracellular but a weaker intracellular blocking effect of Ca2+. The channel activity outlasted the cyclic nucleotide pulses for hundreds of milliseconds when higher agonist concentrations (> 50 microM cAMP) were applied. The duration of the response was longer than in cyclic nucleotide-gated channels from other species studied so far. The plateau duration and the decay remained constant for pulses with a length of 50-150 ms, whereas pulses shorter than 50 ms successively reduced the time required by shortening the plateau phase. A larger difference for the K1/2 values of cAMP (K1/2 = 22 microM) and cGMP (K1/2 = 2.5 microM) were found for a small group (n = 3) of cyclic nucleotide-gated channels, pointing to the selective expression of the alpha-subunit in a small subgroup of olfactory receptor neurons.
Thüraüf
N
N
Department of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nürnberg, Germany.
Gjuric
M
M
Kobal
G
G
Hatt
H
H
D015415:Biomarkers / Q000737:chemistry; D000242:Cyclic AMP / Q000502:physiology*; D006152:Cyclic GMP / Q000502:physiology*; D006801:Humans; D015640:Ion Channel Gating; D018034:Olfactory Receptor Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques
D015415:Biomarkers; D000242:Cyclic AMP; D006152:Cyclic GMP