title: Potassium ion channels operated by receptor stimulation can be activated simply by raising temperature.
abstract: Application of either dopamine (DA), acetylcholine (ACh), or histamine (HA) to the identified ganglion cells of Aplysia elicits a K(+)-dependent slow hyperpolarization. When temperature of the bathing solution was raised from 22 to 32 degrees C, these cells were also hyperpolarized with a marked increase in K+ conductance. The warm- and transmitter-induced current responses recorded under voltage clamp were not blocked by either 1 mM Ba2+ or 10 mM TEA. Intracellularly injected guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) depressed both warm- and transmitter-induced K+ responses immediately after the injection. Intracellular application of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) caused a gradual, irreversible increase in K+ conductance of the plasma membrane and occluded both responses. Transmitter-induced response markedly decreased when the temperature was raised from 22 to 32 degrees C, suggesting that the response to transmitter was occluded during the warm-induced response. These results suggested that the G-protein regulating the receptor-operated K+ channels could be activated simply by raising temperature.
authors.affiliation: Department of Physiology, School of Medicine, Iwate Medical University, Morioka, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tamazawa
authors.forename: M
authors.initials: M
authors.lastname: Matsumoto
authors.forename: A
authors.initials: A
authors.lastname: Kudo
authors.forename: K
authors.initials: K
authors.lastname: Sasaki
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001048:Aplysia / Q000502:physiology; D001464:Barium / Q000378:metabolism; D004298:Dopamine / Q000494:pharmacology; D004553:Electric Conductivity / Q000187:drug effects / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006632:Histamine / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D013696:Temperature; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D015221:Potassium Channels; D017981:Receptors, Neurotransmitter; D013757:Tetraethylammonium Compounds; D013873:Thionucleotides; D006153:Guanosine Diphosphate; D001464:Barium; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D019789:Tetraethylammonium; C023427:guanosine 5'-O-(2-thiodiphosphate); D006632:Histamine; D019204:GTP-Binding Proteins; D000109:Acetylcholine; D011188:Potassium; D004298:Dopamine