抄録
1. Attempts were made to clarify the mechanism of lipolytic effect of excess potassium on rat brown adipose tissue in vitro.
2. The lipolytic effect of excess potassium on brown adipose tissue was almost completely eliminated in both reserpinized and denervated brown adipose tissues, whereas the lipolytic effect of norepinephrine was rather enhanced.
3. The lipolytic effect of excess potassium as well as of norepinephrine on brown adipose tissue was markedly inhibited by propranolol. A similar inhibitory effect of propranolol on the lipolytic effect of norepinephrine was also demonstrated in epididymal adipose tissue. However, the same dose of propranolol had no influence on the lipolytic action of ACTH and theophylline in epididymal adipose tissue.
4. Barium ions showed some small but intrinsic lipolytic effect on brown adipose tissue. This lipolytic effect was evidenced by combining theophylline and was markedly increased in an excess potassium medium.
5. Excess potassium in the medium caused a marked increase in the disappearance rate of norepinephrine from brown adipose tissue.
6. The lipolytic effect of norepinephrine on reserpinized rat brown adipose tissue was markedly increased in an excess potassium medium.
7. From these results, it is suggested that the lipolytic effect of excess potassium on brown adipose tissue was mediated through norepinephrine release from adrenergic nerve endings within the tissue. In addition, the possibility of potentiation of the norepinephrine effect per se in the presence of excess potassium was briefly discussed.
