Open AccessNorepinephrine‐Induced Shift in Levels of Adenosine 3′:5′‐monophosphate and ATP Parallel to Increased Respiratory Rate and Lipolysis in Isolated Hamster Brown‐Fat Cells
Author(s) -
PETTERSSON Bertil,
VALLIN Ivar
Publication year - 1976
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1976.tb10170.x
Subject(s) - lipolysis , endocrinology , medicine , hamster , propranolol , norepinephrine , catecholamine , adenosine , adenosine monophosphate , biology , adenosine triphosphate , chemistry , adipose tissue , dopamine
1 Isolated brown fat cells from hamster respond to added catecholamines with a temporary increase in respiratory rate and an extended lipolysis. 2 From experiments with catecholamines and α and β‐blockers, the receptors of these cells are classified as β according to classical definition. 3 Norepinephrine induces a rapid increase in adenosine 3′:5′‐monophosphate levels which parallels in time the stimulated respiration. Maximal adenosine 3′:5′‐monophosphate levels are reached within 1–3 min and are followed by a continuous decline. 4 Parallel to the catecholamine‐induced respiration and lipolysis there is a pronounced drop in ATP levels. This energy depletion could be reversed by addition within 5 min after norepinephrine of the β‐blocker propranolol. 5 The nucleotide pattern in isolated hamster brown fat cells after norepinephrine addition was mimicked in experiments with isolated hamster brown fat mitochondria. From these experiments it is concluded that a high ratio of AMP and ADP over ATP decreases the respiratory rate when endogenous free fatty acids are oxidized.