{"id":147495,"date":"2022-10-04T01:23:12","date_gmt":"2022-10-04T06:23:12","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2022\/10\/t-type-ca2-channels-boost-neurotransmission-in-mammalian-cone-photoreceptors"},"modified":"2022-10-04T01:23:12","modified_gmt":"2022-10-04T06:23:12","slug":"t-type-ca2-channels-boost-neurotransmission-in-mammalian-cone-photoreceptors","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2022\/10\/t-type-ca2-channels-boost-neurotransmission-in-mammalian-cone-photoreceptors","title":{"rendered":"T-Type Ca2+ Channels Boost Neurotransmission in Mammalian Cone Photoreceptors"},"content":{"rendered":"<p><a class=\"aligncenter blog-photo\" href=\"https:\/\/lifeboat.com\/blog.images\/t-type-ca2-channels-boost-neurotransmission-in-mammalian-cone-photoreceptors2.jpg\"><\/a><\/p>\n<p>It is a commonly accepted view that light stimulation of mammalian photoreceptors causes a graded change in membrane potential instead of developing a spike. The presynaptic Ca<sup>2+<\/sup> channels serve as a crucial link for the coding of membrane potential variations into neurotransmitter release. Ca<sub>v<\/sub>1.4 L-type Ca<sup>2+<\/sup> channels are expressed in photoreceptor terminals, but the complete pool of Ca<sup>2+<\/sup> channels in cone photoreceptors appears to be more diverse. Here, we discovered, employing whole-cell patch-clamp recording from cone photoreceptor terminals in both sexes of mice, that their Ca<sup>2+<\/sup> currents are composed of low-(T-type Ca<sup>2+<\/sup> channels) and high-(L-type Ca<sup>2+<\/sup> channels) voltage-activated components. Furthermore, Ca<sup>2+<\/sup> channels exerted self-generated spike behavior in dark membrane potentials, and spikes were generated in response to light\/dark transition. The application of fast and slow Ca<sup>2+<\/sup> chelators revealed that T-type Ca<sup>2+<\/sup> channels are located close to the release machinery. Furthermore, capacitance measurements indicated that they are involved in evoked vesicle release. Additionally, RT-PCR experiments showed the presence of Ca<sub>v<\/sub>3.2 T-type Ca<sup>2+<\/sup> channels in cone photoreceptors but not in rod photoreceptors. Altogether, we found several crucial functions of T-type Ca<sup>2+<\/sup> channels, which increase the functional repertoire of cone photoreceptors. Namely, they extend cone photoreceptor light-responsive membrane potential range, amplify dark responses, generate spikes, increase intracellular Ca<sup>2+<\/sup> levels, and boost synaptic transmission.<\/p>\n<p><strong>SIGNIFICANCE STATEMENT<\/strong> Photoreceptors provide the first synapse for coding light information. The key elements in synaptic transmission are the voltage-sensitive Ca<sup>2+<\/sup> channels. Here, we provide evidence that mouse cone photoreceptors express low-voltage-activated Ca<sub>v<\/sub>3.2 T-type Ca<sup>2+<\/sup> channels in addition to high-voltage-activated L-type Ca<sup>2+<\/sup> channels. The presence of T-type Ca<sup>2+<\/sup> channels in cone photoreceptors appears to extend their light-responsive membrane potential range, amplify dark response, generate spikes, increase intracellular Ca<sup>2+<\/sup> levels, and boost synaptic transmission. By these functions, Ca<sub>v<\/sub>3.2 T-type Ca<sup>2+<\/sup> channels increase the functional repertoire of cone photoreceptors.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>It is a commonly accepted view that light stimulation of mammalian photoreceptors causes a graded change in membrane potential instead of developing a spike. The presynaptic Ca2+ channels serve as a crucial link for the coding of membrane potential variations into neurotransmitter release. Cav1.4 L-type Ca2+ channels are expressed in photoreceptor terminals, but the complete [\u2026]<\/p>\n","protected":false},"author":359,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-147495","post","type-post","status-publish","format-standard","hentry","category-futurism"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/147495","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/359"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=147495"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/147495\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=147495"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=147495"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=147495"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}