Inositol 1, 4, 5-Trisphosphate- and Caffeine-Sensitive Ca2+-Storing Organelle in Bovine Adrenal Chromaffin Cells

The Japanese Journal of Pharmacology

Akira Ohga¹  Takeo Hiraga¹  Hiroki Teraoka¹  Tetsuro Taneike²  Ryo Takai² 

[1] Department of Toxicology School of Veterinary Medicine, Rakuno Gakuen University;Department of Veterinary Pharmacology, School of Veterinary Medicine, Rakuno Gakuen University

关键词: Caffeine;    Ca2+ store;    Chromaffin cell;    Inositol 1;    4;    5-trisphosphate;    Organelle;   

DOI  :  10.1254/jjp.72.307

学科分类：药理学

来源: Nihon Yakuri Gakkai Henshuubu / Japanese Pharmacological Society

【 摘 要 】

References(42)The uptake and release properties of Ca2+ by several subcellular fractions of the bovine adrenal medulla were investigated. Investigation by the 45Ca2+ tracer method showed that permeabilized cells and the fractions of mitochondria (MT) and microsomes (MC) caused ATP-dependent Ca2+ uptake in a Ca2+ concentration-dependent manner (pCa 8-4), whereas permeabilized cells and the fractions of secretory granules (SG) were able to accumulate a significant amount of Ca2+ even in the absence of ATP, which was completed by the addition of hexokinase and glucose. In these organelle fractions, Ca2+ uptake in the presence of ATP at pCa 7 and pCa 5.8 was well-correlated with the activity of the NADPH cyiochrome c reductase (marker enzyme for the endoplasmic reticulum) and cytochrome c oxidase (marker enzyme for mitochondria), respectively. As detected by Fura-2 ratiometry, both inositol 1, 4, 5-trisphosphate (IP3) and caffeine caused concentration-dependent Ca2+ releases from permeabilized cells and MC, but not from MT and SG. In an ATP-depleted condition, homogenates still took up a significant amount of Ca2+ but was not able to respond to IP3 and caffeine. These results suggest that the endoplasmic reticulum is a major Ca2+-storing organelle, which releases Ca2+ in response to IP3 and caffeine in bovine adrenal chromaffin cells.

【 授权许可】

Unknown