Effects of adrenalectomy on the alpha-adrenergic regulation of cytosolic free calcium in hepatocytes

Journal Article · Sat Jun 25 04:00:00 EDT 1988 · J. Biol. Chem.; (United States)

OSTI ID:7126107

Freudenrich, C C; Borle, A B

We have previously published that bilateral adrenalectomy in the rat reduces the Ca2+-mediated alpha-adrenergic activation of hepatic glycogenolysis, while it increases the cellular calcium content of hepatocytes. In the experiments presented here, the concentration of cytosolic free calcium (Ca2+i) at rest and in response to epinephrine was measured in aequorin-loaded hepatocytes isolated from sham and adrenalectomized male rats. We found that in adrenalectomized rats the resting Ca2+i was elevated, the rise in Ca2+i evoked by epinephrine was reduced, and the rise in /sup 45/Ca efflux that follows such stimulation was depressed. Furthermore, the slope of the relationship between Ca2+i and calcium efflux was decreased 60% in adrenalectomized. Adrenalectomy did not change Ca2+ release from intracellular calcium pools in response to IP3 in saponin-permeabilized hepatocytes. The EC50 for inositol 1,4,5-triphosphate and the maximal Ca2+ released were similar in both sham and adrenalectomized animals. Finally, the liver calmodulin content determined by radioimmunoassay was not significantly different between sham and adrenalectomized rats. These results suggest that 1) adrenalectomy reduces calcium efflux from the hepatocyte, probably by an effect on the plasma membrane (Ca2+-Mg2+)-ATPase-dependent Ca2+ pump and thus alters cellular calcium homeostasis; 2) adrenalectomy decreases the rise in Ca2+i in response to epinephrine; 3) this decreased rise in Ca2+i is not due to defects in the intracellular Ca2+ storage and mobilization processes; and 4) the effects of adrenalectomy on cellular calcium metabolism and on alpha-adrenergic activation of glycogenolysis are not caused by a reduction in soluble calmodulin.

• Research Organization: Univ. of Pittsburgh, Pennsylvania (USA)
• OSTI ID: 7126107
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 263:18; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ADRENALECTOMY
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METALS
ANIMAL CELLS
ANIMALS
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
CALCIUM
CALCIUM 45
CALCIUM ISOTOPES
CALMODULIN
DAYS LIVING RADIOISOTOPES
DRUGS
ELEMENTS
EVEN-ODD NUCLEI
HOMEOSTASIS
IMMUNOASSAY
IMMUNOLOGY
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LIVER CELLS
MAMMALS
MEDICINE
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
METALS
NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RADIOASSAY
RADIOIMMUNOASSAY
RADIOIMMUNOLOGY
RADIOISOTOPES
RATS
REACTION KINETICS
RECEPTORS
RODENTS
SOMATIC CELLS
SURGERY
SYMPATHOMIMETICS
TRACER TECHNIQUES
VERTEBRATES