Oscillations of cytosolic free calcium concentration in the presence of intracellular antibodies to phosphatidylinositol 4,5-bisphosphate in voltage-clamped guinea-pig hepatocytes.
In liver cells, the stimulation of alpha 1-adrenoceptors by noradrenaline induces the production of Ins(1,4,5)P3 through the degradation of membrane polyphosphoinositides [PtdIns(4,5)P2]. InsP3 evokes in turn the release of Ca2+ from internal stores. Our results show that the internal perfusion of single guinea-pig hepatocytes with monoclonal anti-PtdInsP2 antibody blocks the rise in cytosolic free Ca2+ concn. ([Ca2+]i) evoked by noradrenaline, an InsP3-dependent agonist, but not by the monohydroxylated bile acid taurolithocholate 3-sulphate, which is known to permeabilize the endoplasmic reticulum. In these conditions, the bile acid elicited either fast or slow fluctuations of [Ca2+]i independently of any InsP3 production. The responses to the bile acid were also observed in the absence of external Ca2+. The presence of intracellular anti-PtdInsP2 antibody does not affect the response to a photolytic release of InsP3 (1.5 microM final concn.) from a caged precursor.
Noel
J
J
INSERM U274, Université Paris-Sud, Orsay, France.
Fukami
K
K
Hill
A M
AM
Capiod
T
T
D000818:Animals; D001647:Bile Acids and Salts / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002451:Cell Compartmentation; D002478:Cells, Cultured; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008564:Membrane Potentials; D009638:Norepinephrine / Q000494:pharmacology; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D015398:Signal Transduction
D001647:Bile Acids and Salts; D019269:Phosphatidylinositol 4,5-Diphosphate; D010716:Phosphatidylinositols; D011188:Potassium; D002118:Calcium; D009638:Norepinephrine