ISSN:
1432-2013
Keywords:
Potassium channel
;
ATP-sensitive K+ channel
;
4-Aminopyridine
;
Flickery block
;
Skeletal muscle
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract We have examined the effects of 4-aminopyridine (4-AP) on single ATP-dependent potassium channels in patches excised from frog skeletal muscle. 4-AP applied to the internal face of the membrane caused a flickery block. We could not detect any flickery block when 10 mM 4-AP was applied to the external surface of the membrane. The reduction in mean unitary current by internal 4-AP was consistent with 1∶1 binding with a K d of 3.3 mM at 0 mV. The block was voltage-dependent, increasing with depolarization with an effective valency of 0.57. Rate constants for blocking and unblocking by 4-AP were obtained by fitting β functions to the distribution of current amplitudes. Both rate constants were voltage-dependent. At 0 mV they were 17 mM−1 ms−1 and 61 ms−1. Simulation of the block using these rate constants produced a flickery block very similar to that observed experimentally.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00373743
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