A role for calcium/calmodulin kinase in insulin stimulated glucose transport

• Published in: Life sciences (1973) Vol. 74; no. 7; pp. 815 - 825
• Main Authors: Wright, D.C, Fick, C.A, Olesen, J.B, Lim, K, Barnes, B.R, Craig, B.W
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 02.01.2004
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - analogs & derivatives; 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine - pharmacology; Animals; Blotting, Western; Calcium Channel Blockers - metabolism; Calcium Channels, L-Type - drug effects; Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calcium-Calmodulin-Dependent Protein Kinases - antagonists & inhibitors; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; CAMKII; Drug Combinations; Drug Synergism; Enzyme Inhibitors - pharmacology; Glucose - metabolism; Glucose transport; Hypoglycemic Agents - pharmacology; In Vitro Techniques; Insulin; Insulin - pharmacology; Male; Monosaccharide Transport Proteins; Muscle, Skeletal - drug effects; Muscle, Skeletal - enzymology; Nifedipine - pharmacology; Phosphorylation; Rat skeletal muscle; Rats; Rats, Sprague-Dawley; CAMKII; Glucose transport; Insulin; Rat skeletal muscle
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2003.06.041

Previous research has shown that the CAMK (calcium/calmodulin dependent protein kinase) inhibitor, KN62, can lead to reductions in insulin stimulated glucose transport. Although controversial, an L-type calcium channel mechanism has also been hypothesized to be involved in insulin stimulated glucose transport. The purpose of this report was to determine if 1) L-type calcium channels and CAMK are involved in a similar signaling pathway in the control of insulin stimulated glucose transport and 2) determine if insulin induces an increase in CAMKII phosphorylation through an L-type calcium channel dependent mechanism. Insulin stimulated glucose transport was significantly (p<0.05) inhibited to a similar extent (∼30%) by both KN62 and nifedipine in rat soleus and epitrochelaris muscles. The new finding of these experiments was that the combined inhibitory effect of these two compounds was not greater than the effect of either inhibitor alone. To more accurately determine the interaction between CAMK and L-type calcium channels, we measured insulin induced changes in CAMKII phosphorylation using Western blot analysis. The novel finding of this set of experiments was that insulin induced an increase in phosphorylated CAMKII (∼40%) in rat soleus muscle that was reversed in the presence of KN62 but not nifedipine. Taken together these results suggest that a CAMK signaling mechanism may be involved in insulin stimulated glucose transport in skeletal muscle through an L-type calcium channel independent mechanism.