366 



CELLS, TISSUES, AND ORGANISMS 



turnover rate, their metabolic lability, and their high rate of utilization 

 by extrahepatic tissues, are considered to represent a principal form 

 in which fat is mobilized, transported, and oxidized. 



Raben and Hollenberg (1959) were the first to demonstrate that 

 the administration of small doses of growth hormone to fasting dogs 

 and human subjects was followed by a rapid rise in the plasma FFA 

 concentration. This phenomenon has been confirmed by many labora- 

 tories, including our own. In the fasting hypophysectomized rhesus 

 monkey, a rapid rise in circulating FFA can be elicited by a single 

 intramuscular injection of simian growth hormone at a dose of 0.05 

 milligram per kilogram (Goodman and Knobil, 1959). In the fed ani- 

 mal, however, this response is much reduced. Growth hormone appears 

 to be specific in this regard, as illustrated in Figures 5 and 6. Of all the 

 pituitary preparations examined, regardless of dose, only primate 

 growth hormone is active in increasing the plasma concentration of 



PLASMA 

 NEFA 



M Eq./cc. 



— ^— ^ SIMIAN GROWTH HORMONE aSmg./Kg. 



FASTING CONTROL 



100 lU. OVINE PROLACTIN 



25 lU. BOVINE ACTH 



10 lU. BOVINE TSH 



30 U. PITUITRIN 



ALL HORMONES ADMINISTERED IN WATER 

 LM. AT TIME 



4 



TIME IN HOURS 



Figure 5. The effect of a primate growth-hormone preparation and of pro- 

 lactin, ACTH, TSH, and pituitrin on the concentration of non-esterified fatty 

 acids in the plasma of fasting, hypophysectomized rhesus monkeys. (From 

 Goodman and Knobil, 1959). 



