Action potential refractory period in ureter smooth muscle is set by Ca sparks and BK channels

Article Abstract:

A demonstration states that a negative feedback process, which depends on Ca(super 2+) loading the sarcoplasmic reticulum (SR) during the action potential and on the subsequent activation of local releases of Ca(super 2+) from the SR, stimulating plasmalemmal Ca(super 2+) -sensitive K(super +) (BK) channels, determines the refractory period of the action potential. As sparks gradually reduce the Ca(super 2+) load in the SR, electrical inhibition is released, the refractory period is terminated and peristaltic contractions occur again.

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Probing ion-channel pores one proton at a time

Article Abstract:

A self consistent, residue by residue description of the microenvironment around the porelining transmembrane alpha-helices (M2) in the open channel conformtion, in terms of the excess free energy that is required to keep the engineered basic side chains protonated relative to bulk water is presented. A comparison with closed channel data propose that the rotation of M2, is frequently invoked as a hallmark of the gating mechanism of Cys-loop receptors, is minimal.

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Tightrope act

Article Abstract:

A component of the 'tip link' that conveys tension to mechanically sensitive ion channels in the inner ear has been identified. The way in which Nicolson and colleagues and Muller and co-workers identified a major constituent of the 'tip link' is discussed.

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