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Glucagon releases Ca/sup 2 +/ from a FCCP-sensitive pool

Conference · · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)
OSTI ID:7246460
The effects of physiological levels of glucagon on Ca/sup 2 +/ efflux were examined in the perfused rat liver. Two methods were used to estimate Ca/sup 2 +/ efflux: (1) prior labeling of the Ca/sup 2 +/ pools with /sup 45/Ca/sup 2 +/, and (2) measurement of perfusate Ca/sup 2 +/ with atomic absorption. According to both methods, glucagon administration at the physiological level evoked Ca/sup 2 +/ release. In order to identify the hormone-sensitive Ca/sup 2 +/ pool, a method employed by several laboratories was used. In this method, mitochondrial Ca/sup 2 +/ is released by FCCP, (carbonyl-cyanide 4 (trifluoro/methoxy) phenylhydrazone), a mitochondrial uncoupler. The effect of hormones on Ca/sup 2 +/ release after such uncoupler administration is measured. A decreased release is taken as an indication that the pool is entirely or partially mitochondrial. FCCP released 90 +/- 29 nmoles Ca/sup 2 +//gr wet liver. Glucagon (5 x 10/sup -9/ M) released 107 +/- 45 nmoles Ca/sup 2 +//gr wet liver before and 26 +/- 9 nmoles Ca/sup 2 +//gr wet liver after FCCP. These data indicate that glucagon releases Ca/sup 2 +/ mostly from the mitochondria.
Research Organization:
Univ. of Texas Medical School, Houston
OSTI ID:
7246460
Report Number(s):
CONF-8606151-
Conference Information:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
Country of Publication:
United States
Language:
English