TY - JOUR
T1 - Acetylcholine receptor channel properties during development of Xenopus muscle cells in culture.
AU - Brehm, P.
AU - Kidokoro, Y.
AU - Moody-Corbett, F.
PY - 1984/12/1
Y1 - 1984/12/1
N2 - Developmental changes in acetylcholine (ACh) receptor channel function on aneural cultures of embryonic myotomal muscle cells were examined using the patch‐clamp technique. At all stages of differentiation two different unitary‐event amplitudes were observed, corresponding to high‐gamma (single‐channel conductance) (64 pS) and low‐gamma (46 pS) channel types. No change in conductance occurred for either channel type during the 6‐day in vitro period examined. At resting membrane potential (‐85 mV) the low‐gamma channel exhibited a mean open time of approximately 2 ms which, on the average, was 2‐3‐fold longer than that measured for the high‐gamma channel. Neither the estimated mean channel open time nor the voltage dependence of the open state measured for either channel type changed during development. In recordings with low ACh concentration (0.1‐0.25 microM) both high‐gamma and low‐gamma channel types exhibited non‐stationary opening probabilities over the recording period. Usually the opening rate of both channel types decreased with time following seal formation, however, the 'drop‐out' rate was faster for the low‐gamma channel. A developmental increase in the proportion of high‐gamma events occurred between day 1 (16%) and day 5 (56%) in culture, paralleling the time‐dependent changes in the channel kinetics based on ACh‐activated membrane noise. We conclude that the development of non‐junctional muscle membrane is associated with increased expression of high‐gamma channels and that this process is primarily responsible for the previously reported developmental alterations in macroscopic ACh receptor channel currents.
AB - Developmental changes in acetylcholine (ACh) receptor channel function on aneural cultures of embryonic myotomal muscle cells were examined using the patch‐clamp technique. At all stages of differentiation two different unitary‐event amplitudes were observed, corresponding to high‐gamma (single‐channel conductance) (64 pS) and low‐gamma (46 pS) channel types. No change in conductance occurred for either channel type during the 6‐day in vitro period examined. At resting membrane potential (‐85 mV) the low‐gamma channel exhibited a mean open time of approximately 2 ms which, on the average, was 2‐3‐fold longer than that measured for the high‐gamma channel. Neither the estimated mean channel open time nor the voltage dependence of the open state measured for either channel type changed during development. In recordings with low ACh concentration (0.1‐0.25 microM) both high‐gamma and low‐gamma channel types exhibited non‐stationary opening probabilities over the recording period. Usually the opening rate of both channel types decreased with time following seal formation, however, the 'drop‐out' rate was faster for the low‐gamma channel. A developmental increase in the proportion of high‐gamma events occurred between day 1 (16%) and day 5 (56%) in culture, paralleling the time‐dependent changes in the channel kinetics based on ACh‐activated membrane noise. We conclude that the development of non‐junctional muscle membrane is associated with increased expression of high‐gamma channels and that this process is primarily responsible for the previously reported developmental alterations in macroscopic ACh receptor channel currents.
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U2 - 10.1113/jphysiol.1984.sp015497
DO - 10.1113/jphysiol.1984.sp015497
M3 - Article
C2 - 6096531
AN - SCOPUS:0021646379
SN - 0022-3751
VL - 357
SP - 203
EP - 217
JO - The Journal of Physiology
JF - The Journal of Physiology
IS - 1
ER -