Age-associated alterations in hepatic. beta. -adrenergic receptor/adenylate cyclase complex

Journal Article · Tue Sep 01 00:00:00 EDT 1987 · Am. J. Physiol.; (United States)

OSTI ID:6863550

Graham, S M; Herring, P A; Arinze, I J

The effect of age on catecholamine regulation of hepatic glycogenolysis and on hepatic adenylate cyclase was studied in male rats up to 24 mo of age. Epinephrine and norepinephrine stimulated glycogenolysis in isolated hepatocytes at all age groups studied. Isoproterenol, however, stimulated glycogenolysis only at 24 mo. In isolated liver membranes, usual activators of adenylate cyclase increased the activity of the enzyme considerably more in membranes from 24-mo-old rats than in membranes from either 3- or 22-mo-old rats. The Mn/sup 2 +/-dependent activity of the cyclase was increased by 2.9-fold in 3-mo-old animals and approx. 5.7-fold in 24-mo-old rats, indicating a substantial age-dependent increase in the intrinsic activity of the catalytic unit. The density of the ..beta..-adrenergic receptor, as measured by the binding of (/sup 125/I)-iodocyanopindolol to plasma membranes, was 5-8 fmol/mg protein in rats aged 3-12 mo but increased to 19 fmol/mg protein in 24-mo-old rats. Computer-aided analysis of isoproterenol competition of the binding indicated a small age-dependent increase in the proportion of ..beta..-receptors in the high-affinity state. These observations suggest that ..beta..-receptor-mediated hepatic glycogenolysis in the aged rat is predicated upon increases in the density of ..beta..-receptors as well as increased intrinsic activity of the catalytic unit of adenylate cyclase.

• Research Organization: Meharry Medical College, Nashville, TN (USA)
• OSTI ID: 6863550
• Journal Information: Am. J. Physiol.; (United States), Journal Name: Am. J. Physiol.; (United States) Vol. 253:3; ISSN AJPHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
AGE DEPENDENCE
AMINES
ANIMAL CELLS
AROMATICS
ATP
AUTONOMIC NERVOUS SYSTEM AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMISTRY
BODY
CATECHOLAMINES
CELL CONSTITUENTS
CELL MEMBRANES
CHEMISTRY
COMPLEXES
CYCLASES
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ENZYME ACTIVITY
ENZYMES
GLANDS
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
IODINE 125
IODINE ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLED COMPOUNDS
LIGHT NUCLEI
LIVER
LIVER CELLS
LYASES
MANGANESE COMPOUNDS
MEMBRANE PROTEINS
MEMBRANES
NUCLEI
NUCLEOTIDES
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
PHENOLS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
POLYPHENOLS
PROTEINS
RADIOISOTOPES
RADIORECEPTOR ASSAY
RECEPTORS
SOMATIC CELLS
SYMPATHOMIMETICS
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
TRITIUM COMPOUNDS