TY - JOUR
T1 - The action of amyotrophic lateral sclerosis immunoglobulins on mammalian single skeletal muscle Ca2+ channels.
AU - Magnelli, V.
AU - Sawada, T.
AU - Delbono, O.
AU - Smith, R. G.
AU - Appel, Stanley H.
AU - Stefani, E.
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1993/2/1
Y1 - 1993/2/1
N2 - 1. The planar phospholipid bilayer technique was used to study the T-tubule skeletal muscle dihydropyridine (DHP)sensitive calcium (Ca2+) channel. To improve the signal-to-noise ratio, Ca2+ channel activity was recorded using both 800-50 and 500-50 mM NaCl gradients. 2. Ca2+ channels were characterized by their cation selectivity and pharmacological profile. The mean open time for channels identified by these techniques was increased by the DHP agonist Bay K 8644 (2 μM), while it was decreased by the DHP antagonist nifedipine (5 μM). Nifedipine also reduced Ca2+ channel amplitude levels. 3. Immunoglobulins G (IgG) from three amyotrophic lateral sclerosis (ALS) patients (n = 14 experiments), one myasthenia gravis (MG) patient (n = 3 experiments) and one healthy individual (n = 4 experiments), were tested on Ca2+ channel activity at a final concentration of 3 mg/ml. 4. Channel mean open time, mean closed time and time integral for the current were not modified by normal IgG (n = 4 experiments). Similarly, MG IgG did not reduce channel activity (n = 3 experiments). 5. ALS IgG reduced the mean open time of DHP-sensitive Ca2+ channel activity in twelve out of fourteen experiments. In addition, in five out of twelve experiments, ALS IgG stabilized the channel to a smaller amplitude level. 6. ALS IgG reduced Ca2+ channel activity in a side-selective fashion, probably corresponding to the external side of the channel. 7. These results suggest that ALS IgG action on DHP-sensitive Ca2+ channels is not mediated by second messengers, thus favouring a direct mechanism for interaction with the DHP receptor complex.
AB - 1. The planar phospholipid bilayer technique was used to study the T-tubule skeletal muscle dihydropyridine (DHP)sensitive calcium (Ca2+) channel. To improve the signal-to-noise ratio, Ca2+ channel activity was recorded using both 800-50 and 500-50 mM NaCl gradients. 2. Ca2+ channels were characterized by their cation selectivity and pharmacological profile. The mean open time for channels identified by these techniques was increased by the DHP agonist Bay K 8644 (2 μM), while it was decreased by the DHP antagonist nifedipine (5 μM). Nifedipine also reduced Ca2+ channel amplitude levels. 3. Immunoglobulins G (IgG) from three amyotrophic lateral sclerosis (ALS) patients (n = 14 experiments), one myasthenia gravis (MG) patient (n = 3 experiments) and one healthy individual (n = 4 experiments), were tested on Ca2+ channel activity at a final concentration of 3 mg/ml. 4. Channel mean open time, mean closed time and time integral for the current were not modified by normal IgG (n = 4 experiments). Similarly, MG IgG did not reduce channel activity (n = 3 experiments). 5. ALS IgG reduced the mean open time of DHP-sensitive Ca2+ channel activity in twelve out of fourteen experiments. In addition, in five out of twelve experiments, ALS IgG stabilized the channel to a smaller amplitude level. 6. ALS IgG reduced Ca2+ channel activity in a side-selective fashion, probably corresponding to the external side of the channel. 7. These results suggest that ALS IgG action on DHP-sensitive Ca2+ channels is not mediated by second messengers, thus favouring a direct mechanism for interaction with the DHP receptor complex.
UR - http://www.scopus.com/inward/record.url?scp=0027498959&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027498959&partnerID=8YFLogxK
U2 - 10.1113/jphysiol.1993.sp019504
DO - 10.1113/jphysiol.1993.sp019504
M3 - Article
C2 - 8394422
AN - SCOPUS:0027498959
SN - 0022-3751
VL - 461
SP - 103
EP - 118
JO - The Journal of Physiology
JF - The Journal of Physiology
IS - 1
ER -