Abstract
Background: The impact of local anesthetics on the regulation of glucose homeostasis by protein kinase B (Akt) and 5′-adenosine monophosphate-activated protein kinase (AMPK) is unclear but important because of the implications for both local anesthetic toxicity and its reversal by IV lipid emulsion (ILE). Methods: Sprague-Dawley rats received 10 mg/kg bupivacaine over 20 s followed by nothing or 10 ml/kg ILE (or ILE without bupivacaine). At key time points, heart and kidney were excised. Glycogen content and phosphorylation levels of Akt, p70 s6 kinase, s6, insulin receptor substrate-1, glycogen synthase kinase-3β, AMPK, acetyl-CoA carboxylase, and tuberous sclerosis 2 were quantified. Three animals received Wortmannin to irreversibly inhibit phosphoinositide-3-kinase (Pi3k) signaling. Isolated heart studies were conducted with bupivacaine and LY294002-a reversible Pi3K inhibitor. Results: Bupivacaine cardiotoxicity rapidly dephosphorylated Akt at S473 to 63 ± 5% of baseline and phosphorylated AMPK to 151 ± 19%. AMPK activation inhibited targets downstream of mammalian target of rapamycin complex 1 via tuberous sclerosis 2. Feedback dephosphorylation of IRS1 to 31 ± 8% of baseline sensitized Akt signaling in hearts resulting in hyperphosphorylation of Akt at T308 and glycogen synthase kinase-3β to 390 ± 64% and 293 ± 50% of baseline, respectively. Glycogen accumulated to 142 ± 7% of baseline. Irreversible inhibition of Pi3k upstream of Akt exacerbated bupivacaine cardiotoxicity, whereas pretreating with a reversible inhibitor delayed the onset of toxicity. ILE rapidly phosphorylated Akt at S473 and T308 to 150 ± 23% and 167 ± 10% of baseline, respectively, but did not interfere with AMPK or targets of mammalian target of rapamycin complex 1. Conclusion: Glucose handling by Akt and AMPK is integral to recovery from bupivacaine cardiotoxicity and modulation of these pathways by ILE contributes to lipid resuscitation.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 428-442 |
| Number of pages | 15 |
| Journal | Anesthesiology |
| Volume | 124 |
| Issue number | 2 |
| DOIs | |
| State | Published - Feb 1 2016 |
| Externally published | Yes |
Funding
Dr. Fettiplace was supported by an American Heart Association (Dallas, Texas) predoctoral fellowship 13PRE16810063 and the Department of Anesthesiology at the University of Illinois Hospital and Health Science Center (Chicago, Illinois). Drs. Weinberg and Rubinstein were funded by a U.S. Veterans Administration (Washington, D.C.) Merit Review and a National Institutes of Health CounterACT grant 1U01NS083457-01. Dr. Weinberg was awarded a U.S. patent related to lipid resuscitation, is cofounder of ResQ Pharma, Inc. (Chicago, Illinois), with Dr. Rubinstein, and established www.lipidrescue. org, an educational Web site on lipid emulsion as treatment of drug overdose and toxicity. The other authors declare no competing interests.
ASJC Scopus subject areas
- Anesthesiology and Pain Medicine