Calcium homeostasis and cone signaling are regulated by interactions between calcium stores and plasma membrane ion channels.

ABSTRACT: Calcium is a messenger ion that controls all aspects of cone photoreceptor function, including synaptic release. The dynamic range of the cone output extends beyond the activation threshold for voltage-operated calcium entry, suggesting another calcium influx mechanism operates in cones hyperpolarized by light. We have used optical imaging and whole-cell voltage clamp to measure the contribution of store-operated Ca(2+) entry (SOCE) to Ca(2+) homeostasis and its role in regulation of neurotransmission at cone synapses. Mn(2+) quenching of Fura-2 revealed sustained divalent cation entry in hyperpolarized cones. Ca(2+) influx into cone inner segments was potentiated by hyperpolarization, facilitated by depletion of intracellular Ca(2+) stores, unaffected by pharmacological manipulation of vo

SUBMITTER: Szikra T 

PROVIDER: S-EPMC2725299 | biostudies-literature | 2009 Aug

REPOSITORIES: biostudies-literature