| 12200339 |
Lucas P, Shimahara T: Voltage- and calcium-activated currents in cultured olfactory receptor neurons of male Mamestra brassicae (Lepidoptera). Chem Senses. 2002 Sep;27(7):599-610.
Insect olfactory receptor neurons (ORNs) grown in primary cultures were studied using the patch-clamp technique in both conventional and amphotericin B perforated whole-cell configurations under voltage-clamp conditions. After 10-24 days in vitro, ORNs had a mean resting potential of -62 mV and an average input resistance of 3.2 GOmega. Five different voltage-dependent ionic currents were isolated: one Na (+), one Ca (2+) and three K (+) currents. The Na (+) current (35-300 pA) activated between -50 and -30 mV and was sensitive to 1 microM tetrodotoxin (TTX). The sustained Ca (2+) current activated between -30 and -20 mV, reached a maximum amplitude at 0 mV (-4.5 +/- 6.0 pA) that increased when Ba (2+) was added to the bath and was blocked by 1 mM Co (2+). Total outward currents were composed of three K (+) currents: a Ca (2+)-activated K (+) current activated between -40 and -30 mV and reached a maximum amplitude at +40 mV (605 +/- 351 pA); a delayed-rectifier K (+) current activated between -30 and -10 mV, had a mean amplitude of 111 +/- 67 pA at +60 mV and was inhibited by 20 mM tetraethylammonium (TEA); and, finally, more than half of ORNs exhibited an A-like current strongly dependent on the holding potential and inhibited by 5 mM 4-aminopyridine (4-AP). Pheromone stimulation evoked inward current as measured by single channel recordings. |
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