Divalent cations permeation in a Ca2+ non-conducting skeletal muscle dihydropyridine receptor mouse model

Abstract

The dihydropyridine receptor has a function of voltage-gated Ca 2+ channel in muscle • The N617D mutation in the α1 subunit confers non-Ca 2+ conductivity to the channel • Ba 2+ and Mn 2+ ions are found to permeate the mutant channel • External Ca 2+ strongly blocks Ba 2+ currents through the mutant channel • N617D mutation located outside the selectivity filter influences channel permeation

Superfast excitation–contraction coupling in adult zebrafish skeletal muscle fibers

“…Prior to trituration, the bottom of the experimental chamber was covered with a thin layer of silicone grease. This enabled single fibers from zebrafish or mouse to be covered with additional silicone, so that a 50–100-μm-long portion of the fiber extremity was left out, as previously described ( Idoux et al, 2020 ). The culture medium solution was replaced by the extracellular solutions (see Solutions).…”

Anoctamin 5 Knockout Mouse Model Recapitulates LGMD2L Muscle Pathology and Offers Insight Into in vivo Functional Deficits

“…Single fibers were isolated by a 50-minute enzymatic treatment at 37° C using a Tyrode solution containing 2 mg/mL collagenase type I (Sigma). Fibers were voltage-clamped using the silicone clamp technique as previously described [ 47 ]. Briefly, a major part of a single fiber was electrically insulated with silicone grease and a micropipette was inserted into the fiber through the silicone layer to voltage clamp the portion of the fiber free of grease (50 to 150 μm length) using a patch-clamp amplifier (Bio-Logic RK-400, Claix, France) in whole-cell configuration.…”

“…Single fibers were isolated by a 50-minute enzymatic treatment at 37° C using a Tyrode solution containing 2 mg/mL collagenase type I (Sigma). Fibers were voltage-clamped using the silicone clamp technique as previously described (47).…”

Advances in Ca V 1.1 gating: New insights into permeation and voltage-sensing mechanisms

“…Unlike the N617D mutation, another nonconductive mutation, E1014K [ 9 , 10 ], disrupting the quadruple aspartate motif, contrasts with the report by Idoux et al [ 32 ]. The E1014K mutation on Ca V 1.1 showed enhanced muscle fatigue, altered muscle composition, and metabolic issues in an engineered mouse [ 9 , 10 ].…”

“…The authors found no significant differences in muscle performance or excitability when comparing N617D mice with the wild-type counterpart. Using dissociated FDB fibers from these mice, Idoux and colleagues [ 32 ] observed later that N617D conducted Mn 2+ and Ba 2+ in the absence of extracellular Ca 2+ . The Ba 2+ conductance was potently blocked by Ca 2+ , indicating a higher selectivity for Ca 2+ over Ba 2+ .…”