d-Alanine in the islets of Langerhans of rat pancreas

Abstract

Relatively high levels of D-alanine (D-Ala), an endogenous D-amino acid, have been found in the endocrine systems of several animals, especially in the anterior pituitary; however, its functional importance remains largely unknown. We observed D-Ala in islets of Langerhans isolated from rat pancreas in significantly higher levels than in the anterior/intermediate pituitary; specifically, 180 ± 60 fmol D-Ala per islet (300 ± 100 nmol/g islet), and 10 ± 2.5 nmol/g of wet tissue in pituitary. Additionally, 12 ± 5% of the free Ala in the islets was in the D-isomer, almost an order of magnitude higher than the percentage of D-Ala found in the pituitary. Surprisingly, glucose stimulation of the islets resulted in D-Ala release of 0.6 ± 0.5 fmol per islet. As D-Ala is stored in islets and released in response to changes in extracellular glucose, D-Ala may have a hormonal role.

Improving the sensitivity in chiral capillary electrophoresis

“…LIF is the detection system which offers the best sensitivity of all the detectors used in CE and an evidence of this is the low LODs depicted in Table , generally in the nanomolar range even though the reported works did not employ additional preconcentration strategies . Moreover, in a recent published review article, it was demonstrated that LIF has been the most employed detector system in CE to determine chiral neuroactive molecules (e.g.…”

Chiral Measurement of Aspartate and Glutamate in Single Neurons by Large-Volume Sample Stacking Capillary Electrophoresis

“…26,29,46,54 Employing multiple analytical techniques to measure the same analytes from the same samples can provide greater confidence for such measurements. 62 Unfortunately, these ancillary approaches are not always effective for single cell measurements.…”

“…52 With regard to D-AA analyses at single cell and subcellular levels, these have been largely accomplished with chiral capillary electrophoresis (CE) paired with LIF detection. 11,53,54 …”

Recent advances in amino acid analysis by capillary electromigration methods, 2013–2015

“…The amount of D‐Ala in the anterior pituitary and islets of Langerhans of rat pancreas is increased by glucose stimulation. The NDA labeled D‐AA were chirally separated and quantified by CE‐LIF with a nonaqueous separation electrolyte (NACE separation) but requests an D‐amino acid oxidase pretreatment and preconcentration step . Finally, CE‐LIF allowed to measure L‐Met, L‐Cys, Taurine, glutathione on male and female rats liver and to determine if the glutamyl cycle is sex‐gender specific .…”