EFFECTS OBSERVED IN THE WHOLE ANIMAL 



249 



in controlling the blood glucose level, iodoacetate by this effect will tend 

 to cause a hypoglycemic reaction. If the animals have been starved and no 

 appreciable glucose absorption is occurring, there is probably a mobiliza- 

 tion of glucose from the liver (and perhaps other tissues) to supply the 

 needs of the body. There is no evidence that iodoacetate at the doses used 

 significantly alters the renal excretion of glucose, so we can eliminate this 

 factor (see page 192). Iodoacetate at fairly low doses (15 mg/kg) effectively 



tf 



Fig. 1-2G. Schematic representations of how 

 blood ghicose may be altered. The lengths of 

 the arrows indicate roughly the amounts of 

 glucose being transferred between the com- 

 partments. See text for further explanation. 



depresses the accumulation of liver glycogen induced by either insulin or 

 epinephrine (Goldblatt, 1933), but high doses (60 mg/kg) do not interfere 

 with liver glycogenolysis (Noltie, 1935). Hultquist (1958) reasoned that if 

 alloxan alters blood glucose by an action on pancreatic insulin release, iodo- 

 acetate might also, and found some nuclear enlargement of the ^-cells, 

 indicating overactivity, following iodoacetate. Falkmer (1962) observed a 

 nonspecific lowering of islet GSH after the LD50 dose of iodoacetate in 

 Cottus scorpius, but whether this indicates that any of the blood glucose 

 changes are mediated through the pancreas is not known. Another factor 

 of possible importance, especially with high doses of iodoacetate, was em- 

 phasized by Irving (1934), namely, sympathetic stimulation, perhaps origi- 

 nating in the midbrain inasmuch as the hyperglycemic response to iodoace- 



