Inhibition of lobster olfactory receptor cells by an odor-activated potassium conductance

Abstract

1. Whole cell current-clamp recordings show that odors not only depolarize but may also hyperpolarize lobster olfactory receptor cells. Odor-evoked hyperpolarizations occurred in 36% of 178 receptor cells examined. Cell-attached recordings of action potentials followed by current-clamp recordings in the same cell indicate that depolarizing and hyperpolarizing responses were associated with increases (excitation) and decreases (inhibition) in action potential frequency, respectively. Since odorants that hyperpolarized one receptor cell depolarized other cells and since individual cells may be both excited and inhibited, the inhibitory and excitatory nature of the response must be conferred by the odorant-receptor and transduction processes expressed by the receptor cell. 2. The input resistance dropped from 1.73 G omega at rest to 1.45 G omega during odor-evoked hyperpolarization, and the membrane time constant correspondingly decreased from 114 to 61 ms. The increased conductance persisted throughout the stimulation period (5 s). 3. Shifting the K+ reversal to a more negative potential by lowering the [K+]o from 14 to 2.8 mM increased the magnitude of hyperpolarization. The hyperpolarization could be reversibly blocked by dendritic treatment with 5-10 mM 4-aminopyridine (4-AP) or 10 mM cesium ion, but not by 10 mM tetraethylammonium (TEA). 4. Substituting 80% of the [Cl-]o with NO3- increased the amplitude of the hyperpolarization. Based on a calculated equilibrium potential of -32 mV for chloride, an increase in chloride conductance in a low [Cl-]o environment should have decreased the magnitude of the response. Presumably the change in [Cl-]o acts through the dendritic steady-state chloride conductance to shift the membrane potential further from the reversal potential for K+.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional neuroanatomy of the rhinophore of Archidoris pseudoargus

“…Another possibility could be direct inhibition and excitation of sensory cells by chemical stimuli, similar to results found in crustaceans (Michel et al 1991) and squids (Danaceau and Lucero 1998;Lucero et al 1992). Further studies of the sensory neurons within the rhinophore epithelium are needed to clarify these aspects of sensory reception and processing of chemical stimuli in Archidoris.…”

Molecular Cloning of a Lobster Gαq Protein Expressed in Neurons of Olfactory Organ and Brain

“…This suggests that both pathways can coexist in a single ORN. In lobster ORNs this coexistence was established in single-cell recordings of the summation of depolarizing receptor potentials caused by odor-evoked InsPproduction and hyperpolarizing receptor potentials caused by odorevoked cAMP production (McClintock and Ache, 1989b;Michel et al, 1991;Fadool and Ache, 1992;Boekhoff et al, 1994;Hatt and Ache, 1994;Michel and Ache, 1994). The discovery that virtually all odorants can cause depolarizations in one lobster ORN but hyperpolarizations in another supports the hypothesis that this interaction is a mechanism of coincidence detection that allows a smaller number of ORNs to efficiently encode sophisticated information.…”

The influence of chemical complexity on the perception of multicomponent odor mixtures

“…Studies utilizing intra-and extracellular recording techniques with the spiny lobster (see, e.g., Derby, Girardot, & Daniel, 1991a, 1991bGleeson & Ache, 1985;Michel, McLintock, & Ache, 1991; see Ache, 1989, andFine-Levy, 1989, for reviews) and with insects (see, e.g., De Jong & Visser, 1988a, 1988bGetz & Smith, 1990;O'Connell & Akers, 1989) have indicated that the initial site of interaction between individual chemicals in a complex odor stimulus odors (i.e., mixture interactions) is within individual receptor cells in the peripheral olfactory region. This work suggests that this may occur through the interaction ofsecond messenger pathways or receptor mediated events.…”