DEMONSTRATION OF AN ENHANCED α‐ADRENERGIC RESPONSE IN HUMAN ADIPOSE TISSUE WHEN INCUBATED IN PRESENCE OF Li+ INSTEAD OF Na+

Publisher Website
Google Scholar
Abstract
A study has been made of the effect of Li+ on the adrenergic receptor response in human adipose tissue. Subcutaneous adipose tissue was preincubated and incubated in media in which Na+ had been replaced by Li+. The adrenergic response of the tissue was assayed by measuring the rate of lipolysis stimulated with noradrenaline in the presence or absence of phentolamine. The capacity of the hormone‐sensitive lipase was measured by the use of dibutyryl cyclic AMP. The results showed that the α‐adrenergic response was enhanced by the presence of 60 mM Li+, while the β‐adrenergic response was affected only in a higher concentration of Li+ (120 mM). The response of the lipase enzyme to dibutyryl cyclic AMP remained unaffected by Li+, however. The effect of Li+ was inhibited by 0.5 mM La+++ in the medium, indicating that Li+ had increased the entry of Ca++ into the cells. These results suggest that the α‐adrenergic response of human adipose tissue depends on the intracellular concentration of Ca++ for its inhibitory action on the adenyl cyclase enzyme.