Calcium signaling in liver.
In hepatocytes, hormones linked to the formation of the second messenger inositol 1,4,5-trisphosphate (InsP3) evoke transient increases or spikes in cytosolic free calcium ([Ca2+]i), that increase in frequency with the agonist concentration. These oscillatory Ca2+ signals are thought to transmit the information encoded in the extracellular stimulus to down-stream Ca2+-sensitive metabolic processes. We have utilized both confocal and wide field fluorescence microscopy techniques to study the InsP3-dependent signaling pathway at the cellular and subcellular levels in the intact perfused liver. Typically InsP3-dependent [Ca2+]i spikes manifest as Ca2+ waves that propagate throughout the entire cytoplasm and nucleus, and in the intact liver these [Ca2+]i increases are conveyed through gap junctions to encompass entire lobular units. The translobular movement of Ca2+ provides a means to coordinate the function of metabolic zones of the lobule and thus, liver function. In this article, we describe the characteristics of agonist-evoked [Ca2+]i signals in the liver and discuss possible mechanisms to explain the propagation of intercellular Ca2+ waves in the intact organ.
Gaspers
Lawrence D
LD
Department of Pharmacology and Physiology, New Jersey Medical School of University of Medicine and Dentistry of New Jersey, Medical Science Building, H609, 185 South Orange Avenue, P.O. Box 1709, Newark, NJ 07103-1709, USA.
Thomas
Andrew P
AP
D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002450:Cell Communication / Q000502:physiology; D006801:Humans; D008099:Liver / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D010716:Phosphatidylinositols / Q000378:metabolism / Q000502:physiology
D010716:Phosphatidylinositols