title: A direct demonstration that inositol-trisphosphate induces an increase in intracellular calcium in Limulus photoreceptors.
abstract: Inositol-trisphosphate was pressure-injected into Limulus ventral photoreceptors; these injections induced electrical responses that mimic several aspects of the electrical responses induced by light. Single cells were also injected with aequorin. Injections of inositol-trisphosphate into such cells induced an increase in luminescence from the intracellular aequorin, even in the absence of extracellular calcium ions. These aequorin responses show directly that inositol-trisphosphate induces an increase in ionized calcium concentration within intact and functioning cells that arises from release of calcium ions from intracellular stores.
mesh_terms: D000331:Aequorin; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006737:Horseshoe Crabs; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000494:pharmacology*; D008163:Luminescent Measurements; D010786:Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism*; D013403:Sugar Phosphates / Q000494:pharmacology*
chemical_list: D007295:Inositol Phosphates; D013403:Sugar Phosphates; D000331:Aequorin; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium