Ins(1,3,4,5)P4 promotes sustained activation of the Ca(2+(-dependent Cl- current in isolated mouse lacrimal cells.
Infusion of 50 microM-Ins(1,3,4,5)P4 in addition to 500 microM-Ins(1,4,5)P3 into mouse lacrimal cells via a patch-clamp pipette promoted sustained activation of the Ca(2+)-dependent Cl- current, which could not be achieved with 500 microM-Ins(1,4,5)P3 alone. It has been proposed that Ins(1,3,4,5)P4 facilitates Ca2+ influx in the presence of Ins(1,4,5)P3 [Morris, Gallacher, Irvine & Petersen (1987) Nature (London) 330, 653-655], but a subsequent study in mouse lacrimal cells [Bird, Rossier, Hughes, Shears, Armstrong & Putney (1991) Nature (London) 352, 162-165] showed that a high concentration of Ins(1,4,5)P3 could mobilize both intra- and extra-cellular Ca2+ in the absence of Ins(1,3,4,5)P4. My data confirm these findings, but also show that Ins(1,3,4,5)P4 can stimulate additional Ca2+ influx even when the Ins(1,4,5)P3-dependent intracellular Ca2+ pools have been depleted.
Smith
P M
PM
Department of Physiology, University of Liverpool, U.K.
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D018118:Chloride Channels; D005110:Extracellular Space / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000494:pharmacology; D007295:Inositol Phosphates / Q000494:pharmacology*; D007700:Kinetics; D007765:Lacrimal Apparatus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008565:Membrane Proteins / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D013268:Stimulation, Chemical
D018118:Chloride Channels; D007295:Inositol Phosphates; D008565:Membrane Proteins; D015221:Potassium Channels; C081655:inositol-1,3,4,5-tetrakisphosphate; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium