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Evaluation of insulin secretion and action in New World camelids

Anna M. FirshmanDepartment of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.

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Christopher K. CebraDepartment of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331.

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Barbara J. SchanbacherDepartment of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853.

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Elizabeth R. SeaquistDepartment of Medicine, College of Medicine, University of Minnesota, Minneapolis, MN 55108.

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Abstract

Objective—To measure and compare insulin secretion and sensitivity in healthy alpacas and llamas via glucose clamping techniques.

Animals—8 llamas and 8 alpacas.

Procedures—Hyperinsulinemic euglycemic clamping (HEC) and hyperglycemic clamping (HGC) were performed on each camelid in a crossover design with a minimum 48-hour washout period between clamping procedures. The HEC technique was performed to measure insulin sensitivity. Insulin was infused IV at 6 mU/min/kg for 4 hours, and an IV infusion of glucose was adjusted to maintain blood glucose concentration at 150 mg/dL. Concentrations of blood glucose and plasma insulin were determined throughout. The HGC technique was performed to assess insulin secretion in response to exogenous glucose infusion. An IV infusion of glucose was administered to maintain blood glucose concentration at 320 mg/dL for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout.

Results—Alpacas and llamas were not significantly different with respect to whole-body insulin sensitivity during HEC or in pancreatic β-cell response during HGC. Alpacas and llamas had markedly lower insulin sensitivity during HEC and markedly lower pancreatic β-cell response during HGC, in comparison with many other species.

Conclusions and Clinical Relevance—New World camelids had lower glucose-induced insulin secretion and marked insulin resistance in comparison with other species. This likely contributes to the disorders of fat and glucose metabolism that are common to camelids.

Abstract

Objective—To measure and compare insulin secretion and sensitivity in healthy alpacas and llamas via glucose clamping techniques.

Animals—8 llamas and 8 alpacas.

Procedures—Hyperinsulinemic euglycemic clamping (HEC) and hyperglycemic clamping (HGC) were performed on each camelid in a crossover design with a minimum 48-hour washout period between clamping procedures. The HEC technique was performed to measure insulin sensitivity. Insulin was infused IV at 6 mU/min/kg for 4 hours, and an IV infusion of glucose was adjusted to maintain blood glucose concentration at 150 mg/dL. Concentrations of blood glucose and plasma insulin were determined throughout. The HGC technique was performed to assess insulin secretion in response to exogenous glucose infusion. An IV infusion of glucose was administered to maintain blood glucose concentration at 320 mg/dL for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout.

Results—Alpacas and llamas were not significantly different with respect to whole-body insulin sensitivity during HEC or in pancreatic β-cell response during HGC. Alpacas and llamas had markedly lower insulin sensitivity during HEC and markedly lower pancreatic β-cell response during HGC, in comparison with many other species.

Conclusions and Clinical Relevance—New World camelids had lower glucose-induced insulin secretion and marked insulin resistance in comparison with other species. This likely contributes to the disorders of fat and glucose metabolism that are common to camelids.

Contributor Notes

Dr. Firshman's present address is Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108.

Supported by the Morris Animal Foundation.

The study was performed at Oregon State University.

The authors thank Megan Christie, Kristin Peterson, Stephanie Crawford, and Stephen V. Lamb for technical assistance.

Address correspondence to Dr. Firshman (firsh001@umn.edu).