Gustatory receptors and neighbouring cells in the surface layer of an amphibian taste disc: in situ relationships and response to cell isolation

Richter, Hans-Peter; Avenet, Patrick; Mestres, Pedro; Lindemann, Bernd

doi:10.1007/bf00220020

Cited by 21 publications

(20 citation statements)

References 35 publications

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“…The shape of rat TRCs, as observed after micro-dissection, is comparable to amphibian TRCs Richter et al, 1988) and shows a typical elongated apical pole. Rat TRCs are, however, thinner (30/zm in length, 4 #m wide at the soma, and 1 /zm at the apical pole), which explains their smaller membrane capacitance of 3-5 pF.…”

Section: Characteristics Of the Trcsmentioning

confidence: 52%

Membrane currents in taste cells of the rat fungiform papilla. Evidence for two types of Ca currents and inhibition of K currents by saccharin.

Béhé

DeSimone

Avenet

et al. 1990

The Journal of General Physiology

171

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Taste buds were isolated from the fungiform papilla of the rat tongue and the receptor cells (TRCs) were patch clamped. Seals were obtained on the basolateral membrane of 281 TRCs, protruding from the intact taste buds or isolated by micro-dissection. In whole-cell configuration 72% of the cells had a TTX blockable transient Na inward current (mean peak amplitude 0.74 hA). All cells had outward K currents. Their activation was slower than for the Na current and a slow inactivation was also noticeable. The K currents were blocked by tetraethylammonium, Ba, and 4-aminopyridine, and were absent when the pipette contained Cs instead of K. With 100 mM Ba or 100 mM Ca in the bath, two types of inward current were observed. An L-type Ca current (ICaL) activated at -20 mV had a mean peak amplitude of 440 pA and inactivated very slowly. At 3 mM Ca the activation threshold of ICa L was near -40 mV. A transient T-type current (/CAT) activated at -50 mV had an average peak amplitude of 53 pA and inactivated with a time constant of 36 ms at -30 inV. ICR L was blocked more efficiently by Cd and D600 than/Ca T. ICa T was blocked by 0.2 mM Ni and half blocked by 200 #M amiloride. In whole-cell voltage clamp, Na-saccharin caused (in 34% of 55 cells tested) a decrease in outward K currents by 21%, which may be expected to depolarize the TRCs. Also, Na-saccharin caused some taste cells to fire action potentials (on-ceLl, 7 out of 24 cells; whole-ceLl, 2 out of 38 cells responding to saccharin) of amplitudes sufficient to activate/CAL. ThUS the action potentials will cause Ca inflow, which may trigger release of transmitter.

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Section: Characteristics Of the Trcsmentioning

confidence: 52%

Membrane currents in taste cells of the rat fungiform papilla. Evidence for two types of Ca currents and inhibition of K currents by saccharin.

Béhé

DeSimone

Avenet

et al. 1990

The Journal of General Physiology

171

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“…In consequence, some of the cells round off by the shortening of their apical process. They also start to disseminate the "rod-organelle," a dense bundle off-actin which supports the chemosensory apical membrane [48].…”

Section: Alterations In Channel Topologymentioning

confidence: 99%

Amiloride-blockable sodium currents in isolated taste receptor cells

1988

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Isolated taste receptor cells from the frog tongue were investigated under whole-cell patch-clamp conditions. With the cytosolic potential held at -80 mV, more than 50% of the cells had a stationary inward Na current of 10 to 700 pA in Ringer's solution. This current was in some cells partially, in others completely, blockable by low concentrations of amiloride. With 110 mM Na in the external and 10 mM Na in the internal solution, the inhibition constant of amiloride was (at -80 mV) near 0.3 microM. In some cells the amiloride-sensitive conductance was Na specific; in others it passed both Na and K. The Na/K selectivity (estimated from reversal potentials) varied between 1 and 100. The blockability by small concentrations of amiloride resembled that of channels found in some Na-absorbing epithelia, but the channels of taste cells showed a surprisingly large range of ionic specificities. Receptor cells, which in situ express these channels in their apical membrane, may be competent to detect the taste quality "salty." The same cells also express TTX-blockable voltage-gated Na channels.

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“…In mammalian TRCs action potentials were observed by patch clamping cells isolated from the tissue [9]. However, the isolation of taste buds from the tongue and of TRCs from the taste buds caused problems of its own [25]. A more convenient and preferably noninvasive method of recording, suitable for taste cells maintained in the taste bud and in the tongue epithelium, is needed to investigate TRC electrical responses to gustatory stimuli.…”

Section: Introductionmentioning

confidence: 99%

Noninvasive recording of receptor cell action potentials and sustained currents from single taste buds maintained in the tongue: The response to mucosal NaCl and amiloride

1991

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Apical membrane currents were recorded from the taste pore of single taste buds maintained in the tongue of the rat, using a novel approach. Under a dissection microscope, the 150-microns opening of a saline-filled glass pipette was positioned onto single fungiform papillae, while the mucosal surface outside the pipette was kept dry. Electrical responses of receptor cells to chemical stimuli, delivered from the pipette, were recorded through the pipette while the cells remained undamaged in their natural environment. We observed monophasic transient currents of 10-msec duration and 10-100 pA amplitude, apparently driven by action potentials arising spontaneously in the receptor cells. When perfusing the pipette with a solution of increased Na but unchanged Cl concentration, a stationary inward current (from pipette to taste cell) of 50-900 pA developed and the collective spike rate of the receptor cells increased. At a mucosal Na concentration of 250 mM, the maximal collective spike rate of a bud was in the range of 6-10 sec-1. In a phasic/tonic response, the high initial rate was followed by an adaptive decrease to 0.5-2 sec-1. Buds of pure phasic response were also observed. Amiloride (30 microM) present in the pipette solution reversibly and completely blocked the increase in spike rate induced by mucosal Na. Amiloride also decreased reversibly the stationary current which depended on the presence of mucosal Na (inhibition constant near 1 microM). During washout of amiloride, spike amplitudes were first small, then increased, but always remained smaller than the amiloride-blockable stationary current of the bud.(ABSTRACT TRUNCATED AT 250 WORDS)

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Gustatory receptors and neighbouring cells in the surface layer of an amphibian taste disc: in situ relationships and response to cell isolation

Cited by 21 publications

References 35 publications

Membrane currents in taste cells of the rat fungiform papilla. Evidence for two types of Ca currents and inhibition of K currents by saccharin.

Membrane currents in taste cells of the rat fungiform papilla. Evidence for two types of Ca currents and inhibition of K currents by saccharin.

Amiloride-blockable sodium currents in isolated taste receptor cells

Noninvasive recording of receptor cell action potentials and sustained currents from single taste buds maintained in the tongue: The response to mucosal NaCl and amiloride

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