M. Taniguchi et al., INTRACELLULAR DIALYSIS OF CYCLIC-NUCLEOTIDES INDUCES INWARD CURRENTS IN TURTLE VOMERONASAL RECEPTOR NEURONS, The Journal of neuroscience, 16(3), 1996, pp. 1239-1246
Turtle vomeronasal receptor neurons in slice preparations were studied
using the patch-clamp technique in the whole-cell and cell-attached c
onfigurations. The mean resting potential was -48, and the response to
an injected current step consisted of either a single spike or a trai
n of spikes. An injected current of 3-30 pA was required to depolarize
the neuron to spike threshold near -50 mV, Voltage-clamped vomeronasa
l receptor neurons displayed transient inward currents followed by sus
tained outward currents in response to depolarizing voltage steps. In
cell-attached recordings, 10 mu M forskolin added to the bath caused a
transient increase of spike rate. Intracellular application of cAMP e
voked an inward current in a dose-dependent manner from the neurons vo
ltage clamped at -70 mV; 0.1 mM cAMP was sufficient to elicit an inwar
d current in the neurons. The magnitude of the response to cAMP reache
d a plateau at 1 mM with an average peak amplitude of 176 +/- 34 pA. I
ntracellular application of 1 mM cGMP also evoked an inward current wi
th an average peak amplitude of 227 +/- 61 pA. The reversal potentials
of the induced components were estimated to be 10 +/- 7 mV for cAMP a
nd -4 +/- 16 mV for cGMP. The reversal potential of the cAMP-induced c
urrent in external Cl--free solution was similar to that in normal Rin
ger's solution, suggesting that Cl- current is not significantly invol
ved in the current. The present results represent the first evidence o
f cyclic nucleotide-activated conductance in the vomeronasal receptor
membranes.