A cyclic‐AMP‐gated conductance in cochlear hair cells

Abstract

The patch clamp technique was used to record CAMP-dependent currents of the guinea pig cochlear hair cell plasma membrane. Data obtained indicate that the channels passing this current are moderately selective for monovalent cations and are effectively blocked by L-cis-diltiazem and reversibly blocked by 1 mM Mg2' or Ca 2+ The single-channel unit conductance estimated in the absence of divalent cations is about 16 pS. The results demonstrate that cyclic nucleotide-dependent channels of cochlear hair cells are virtually identical to the photoreceptor and olfactory ones.

Regulation of ionic currents by protein kinase A and intracellular calcium in outer hair cells isolated from the guinea-pig cochlea

“…2, its activation has far-reaching consequences for the cells' electrophysiology. A role for cAMP has been proposed in OHCs in gating cation channels [20], but it should be noted that this is quite distinct from the role found here.…”

Ionic currents expressed in a cell line derived from the organ of Corti of the Immortomouse

“…At present little is known of the external factors that could control intracellular cAMP levels in the embryonic organ of Corti. It is possible that the identification of I h in cochlear hair cell precursors may provide an answer to a long-standing problem in hair cell physiology, for the activation of I h by cAMP, via a phosphorylation-independent mechanism, resembles the activation of a nonselective cation conductance in inside-out patches from outer and inner hair cells of young adult guinea-pigs [18]. This latter conductance remains unidentified, but we suggest that it may have a role at earlier stages of development.…”

Perception of sound and gravity by TMC1 and TMC2

“…At one time, a mammalian equivalent of bacterial large-conductance mechanosensitive channels such as MscL was considered a reasonable candidate (5). Cyclic nucleotide-gated (CNG) channels in hair cells (6) have also been prime contenders. However, the rapid dynamic changes required for auditory transduction are in the sub-millisecond range for highfrequency sensing, making such a proposal unlikely to be true (3).…”

“…The tissue DCs respond to this encounter by capturing foreign antigen, processing the antigen to a form that can be recognized by T cells, becoming activated, and, importantly, migrating to the DLNs from the body's surfaces. It is within the DLN that the DCs encounter T cells specific for the antigen/pathogen that they have captured and processed and, thereby, initiate the adaptive immune response (6).…”