[Effect of changes in intracellular calcium concentration on the response of isolated frog retina photoreceptors].
The role of Ca++ in photoreception was studied by releasing these ions in rod cytoplasma from mitochondrias under 2,4 DNP/10(-4) M/action or blocking the transmembrane Ca++ transport by LaCl3 application (0.1; 0.5; 4 mM). The late receptor potential of the frog retina in response to the repeating stimuli after adding 2.4-DNP in the strophantine--containing saline decreases more slowly than in the control. After adding La+++ ions rods and cones generate the receptor potentials of the same amplitude in the Ca++-free solution as in the Ca++--containing medium. La+++ seems to block calcium permeability of the photoreceptor membrane. These results are incompatible with Ca++ inward current as supposed for cones by the Hagins hypothesis. Ca++ seems to act inside photoreceptor as a modulator rather than the transmitter.
D019297:2,4-Dinitrophenol; D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004140:Dinitrophenols / Q000494:pharmacology; D004596:Electroretinography; D066298:In Vitro Techniques; D007811:Lanthanum / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D010786:Photoreceptor Cells / Q000378:metabolism / Q000502:physiology*; D011896:Rana temporaria
D004140:Dinitrophenols; D007811:Lanthanum; D019297:2,4-Dinitrophenol; D002118:Calcium
Vliianie izmeneniia vnutrikletochnoĭ kontsentratsii kal'tsiia na otvet fotoretseptorov izolirovannoĭ setchatki liagushki.