Human cone elongation responses can be explained by photoactivated cone opsin and membrane swelling and osmotic response to phosphate produced by RGS9-catalyzed GTPase.

ABSTRACT: Human cone outer segment (COS) length changes in response to stimuli bleaching up to 99% of L- and M-cone opsins were measured with high resolution, phase-resolved optical coherence tomography (OCT). Responses comprised a fast phase (∼5 ms), during which COSs shrink, and two slower phases (1.5 s), during which COSs elongate. The slower components saturated in amplitude (∼425 nm) and initial rate (∼3 nm ms^-1) and are well described over the 200-fold bleaching range as the sum of two exponentially rising functions with time constants of 80 to 90 ms (component 1) and 1,000 to 1,250 ms (component 2). Measurements with adaptive optics reflection densitometry revealed component 2 to be linearly related to cone pigment bleaching, and the hypothesis is proposed that it arises from cone

SUBMITTER: Pandiyan VP 

PROVIDER: S-EPMC9522364 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature