Thermogenic activity

Thermogenic activity. Chloroform extract of the dried rhizome, at concentrations of 5 and 50 p-g/mL administered by perfusion to the hind limb of rats, stimulated oxygen uptake ° . 

In the case of GC1, modest selectivity for THRp has been described (6.6-fold) which originates from the oxyaceticacid head group [55], In vivo, an increase in selectivity is achieved by accumulation in the liver versus the heart. Ciba-Geigy (now Novartis) discovered the lipid-lowering thyromimetic CGS 26214 devoid of cardiac and thermogenic activity. CGS 26214 was identified based on its ability to access and bind to the nuclear fraction of hepatocytes about 100-fold better compared to that of myocytes in culture. Similar characteristics were reported for L-94901 which was developed by SK F. It was suggested that the liver selectivity of L-94901 is achieved... 

Excessive food intake does not always lead to obesity nor does moderate food intake guarantee leanness. Indeed, the high energetic efficiency of several obese rodents indicate that obesity can in part result from impaired energy expenditure. Recently, research has focused on the relationship between thermogenic activity in brown adipose tissue (BAT) and energy balance. 

The hypothalamic temperature controller (Bl) can be inactivated by neuroleptics (p. 236), without impairment of other centers. Thus, it is possible to lower a patient s body temperature without activating counter-regulatory mechanisms (thermogenic shivering). This can be exploited in the treatment of severe febrile states (hyperpyrexia) or in open-chest surgery with cardiac by-pass, during which blood temperature is lowered to 10°C by means of a heart-lung machine. 

Table 6. The general strategy of a pH-based assay for enzyme activity and selectivity of ThermoGen esterases, if separate isomers are run side-by-side an indication of substrate preference can be developed for each enzyme... 

A potentially harmful effect is the stimulation by E of potassium ion movement from plasma into skeletal muscle and liver P2), which can lead to hypokalemia. This effect is accompanied by a decrease in potassium ion excretion by the kidney. The ability of E to stimulate plasma membrane Na+,K+-ATPase activity in skeletal muscle P2) may partially explain this hypokalemic action, as well as the thermogenic effect of the hormone (see below). 

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