AJP - Cell Physiology, Vol 255, Issue 1 C60-C69, Copyright © 1988 by American Physiological Society
Insulin improves rat soleus axon function by increasing glucose transport
J. B. Pickett
Veterans Administration Medical Center, Charleston, South Carolina.
The effect of varying glucose and insulin concentration on neuromuscular
transmission was investigated in rat soleus and extensor digitorum longus
(EDL) nerve-muscle preparations using conventional microelectrode
techniques. Soleus and EDL axons were similar in that both failed after
approximately 70 min of glucose deprivation and often did not recover from
glucose deprivation. Soleus and EDL axons differed in the following ways:
1) soleus axons required greater than 7.64 mM of glucose to give sustained
function vs. greater than 2.78 mM of glucose for the EDL; 2) 30 microU/ml
of insulin improved soleus axon function over a range of glucose
concentrations from 4.17 to 9.72 mM vs. no effect of 1,000 microU/ml on EDL
axons; 3) resting glucose transport was slow into soleus axons and rapid
into EDL axons; and 4) 10 microU/ml of insulin increased glucose transport
into soleus axons vs. no effect of 1,000 microU/ml of insulin on glucose
transport into EDL axons. These results suggest that insulin improves
soleus axon function by increasing glucose transport, whereas insulin has
no effect on EDL axons.
