Inositol 1,4,5-trisphosphate-induced calcium release is necessary for generating the entire light response of limulus ventral photoreceptors. 2003

Alan Fein
Department of Physiology, University of Connecticut Health Center, Farmington, CT 06030-3505, USA. afein@neuron.uchc.edu

The experiments reported here were designed to answer the question of whether inositol 1,4,5-trisphosphate (IP3)-induced calcium release is necessary for generating the entire light response of Limulus ventral photoreceptors. For this purpose the membrane-permeable IP3 receptor antagonist 2-aminoethoxydiphenyl borate (2APB) (Maruyama, T., T. Kanaji, S. Nakade, T. Kanno, and K. Mikoshiba. 1997. J. Biochem. (Tokyo). 122:498-505) was used. Previously, 2APB was found to inhibit the light activated current of Limulus ventral photoreceptors and reversibly inhibit both light and IP3 induced calcium release as well as the current activated by pressure injection of calcium into the light sensitive lobe of the photoreceptor (Wang, Y., M. Deshpande, and R. Payne. 2002. Cell Calcium. 32:209). In this study 2APB was found to inhibit the response to a flash of light at all light intensities and to inhibit the entire light response to a step of light, that is, both the initial transient and the steady-state components of the response to a step of light were inhibited. The light response in cells injected with the calcium buffer 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) was reversibly inhibited by 2APB, indicating that these light responses result from IP3-mediated calcium release giving rise to an increase in Cai. The light response obtained from cells after treatment with 100 microM cyclopiazonic acid (CPA), which acts to empty intracellular calcium stores, was reversibly inhibited by 2APB, indicating that the light response after CPA treatment results from IP3-mediated calcium release and a consequent rise in Cai. Together these findings imply that IP3-induced calcium release is necessary for generating the entire light response of Limulus ventral photoreceptors.

UI MeSH Term Description Entries
D008027 Light That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range. Light, Visible,Photoradiation,Radiation, Visible,Visible Radiation,Photoradiations,Radiations, Visible,Visible Light,Visible Radiations
D001896 Boron Compounds Inorganic or organic compounds that contain boron as an integral part of the molecule. Borides,Compounds, Boron
D002118 Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D006737 Horseshoe Crabs An arthropod subclass (Xiphosura) comprising the North American (Limulus) and Asiatic (Tachypleus) genera of horseshoe crabs. Crabs, Horseshoe,Limulus,Limulus polyphemus,Tachypleus,Xiphosura,Crab, Horseshoe,Horseshoe Crab,Xiphosuras
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014785 Vision, Ocular The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain. Vision,Light Signal Transduction, Visual,Ocular Vision,Visual Light Signal Transduction,Visual Phototransduction,Visual Transduction,Phototransduction, Visual,Transduction, Visual
D015220 Calcium Channels Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue. Ion Channels, Calcium,Receptors, Calcium Channel Blocker,Voltage-Dependent Calcium Channel,Calcium Channel,Calcium Channel Antagonist Receptor,Calcium Channel Antagonist Receptors,Calcium Channel Blocker Receptor,Calcium Channel Blocker Receptors,Ion Channel, Calcium,Receptors, Calcium Channel Antagonist,VDCC,Voltage-Dependent Calcium Channels,Calcium Channel, Voltage-Dependent,Calcium Channels, Voltage-Dependent,Calcium Ion Channel,Calcium Ion Channels,Channel, Voltage-Dependent Calcium,Channels, Voltage-Dependent Calcium,Voltage Dependent Calcium Channel,Voltage Dependent Calcium Channels
D015544 Inositol 1,4,5-Trisphosphate Intracellular messenger formed by the action of phospholipase C on phosphatidylinositol 4,5-bisphosphate, which is one of the phospholipids that make up the cell membrane. Inositol 1,4,5-trisphosphate is released into the cytoplasm where it releases calcium ions from internal stores within the cell's endoplasmic reticulum. These calcium ions stimulate the activity of B kinase or calmodulin. 1,4,5-InsP3,Inositol 1,4,5-Triphosphate,Myo-Inositol 1,4,5-Trisphosphate,1,4,5-IP3,Myoinositol 1,4,5-Triphosphate
D053496 Inositol 1,4,5-Trisphosphate Receptors Intracellular receptors that bind to INOSITOL 1,4,5-TRISPHOSPHATE and play an important role in its intracellular signaling. Inositol 1,4,5-trisphosphate receptors are calcium channels that release CALCIUM in response to increased levels of inositol 1,4,5-trisphosphate in the CYTOPLASM. Inositol 1,4,5-Triphosphate Receptor,Inositol 1,4,5-Triphosphate Receptors,Inositol 1,4,5-Trisphosphate Receptor,1,4,5-INTP Receptor,INSP3 Receptor,INSP3 Receptor Type 1,INSP3 Receptor Type 2,INSP3 Receptor Type 3,IP3 Receptor,Inositol 1,4,5-trisphosphate Receptor Subtype 3,Inositol 1,4,5-trisphosphate Receptor Type 1,Inositol 1,4,5-trisphosphate Receptor Type 2,Inositol 1,4,5-trisphosphate Receptor Type 3,Inositol Triphosphate Receptor,Inositol-1,4,5-Triphosphate Receptor,Receptor, Inositol-1,4,5-triphosphate,Type 1 Inositol 1,4,5-trisphosphate Receptor,Type 3 Inositol 1,4,5-trisphosphate Receptor,Receptor, INSP3,Receptor, IP3,Receptor, Inositol Triphosphate,Triphosphate Receptor, Inositol
D017956 Photoreceptor Cells, Invertebrate Specialized cells in the invertebrates that detect and transduce light. They are predominantly rhabdomeric with an array of photosensitive microvilli. Illumination depolarizes invertebrate photoreceptors by stimulating Na+ influx across the plasma membrane. Invertebrate Photoreceptors,Photoreceptors, Invertebrate,Invertebrate Photoreceptor Cells,Cell, Invertebrate Photoreceptor,Cells, Invertebrate Photoreceptor,Invertebrate Photoreceptor,Invertebrate Photoreceptor Cell,Photoreceptor Cell, Invertebrate,Photoreceptor, Invertebrate

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