Abstract
Extracted tissue phospholipid 31P NMR profiles, obtained from individual porcine lenses subjected to two preservation procedures (acetone desiccation and freeze-drying) and a perchloric acid-extraction procedure, were compared to those from freshly excised lens specimens. Each profile yielded quantitative data on 12 lens phospholipids: PC, LPC, PC plas, PE, LPE, PE plas, PS, SPH, PI, LPI, PG, and CL. A specimen group size of at least 9 lenses was required for secure statistical inter-group comparisons by the Scheffé procedure, due to specimen 31P NMR profile variability, interpreted as arising from specimen biological variability. The phospholipid profiles of lenses preserved by acetone desiccation were essentially identical to those from the freshly excised control lenses. Freeze-dried lens profiles differed significantly in four components, while profiles from perchloric acid-extracted lenses differed in six. It is concluded that specimen preservation by acetone disiccation is a useful method for preserving tissue phospholipids for subsequent 31P NMR profile analysis, while freeze-drying is not. Lipid extraction following a tissue acid extraction is also of little or no value in the determination of tissue phospholipid profiles.
Highlights
110 It is concluded that specimen preservatibn by acetone disiccation is a useful method for preserving tissue phospholipids for subsequent "P NMR profile analysis, while freeze-drying is not
This study compares tissue phospholipid profiles obtained from porcine lenses subjected, upon excision from fresh porcine globes, to three procedures: acetone desiccation, freeze-drying, and lipid extraction following perchloric acid (PCA) extraction
Quantitation of minor resonances remains within the limits imposed by specimen biological variability so long as the signal-to-noise ratio of a resonance is greater than about 5.Signals lyingjust above the spectral noise will exhibit wide-rangingvariability [1]
Summary
110 It is concluded that specimen preservatibn by acetone disiccation is a useful method for preserving tissue phospholipids for subsequent "P NMR profile analysis, while freeze-drying is not. This study compares tissue phospholipid profiles obtained from porcine lenses subjected, upon excision from fresh porcine globes, to three procedures: acetone desiccation, freeze-drying, and lipid extraction following PCA extraction. The acidic aqueous extract is immediately transferred to a volume of 10 M KOH equivalent to that of the PCA used, where it is neutralized and prepared for subsequent NMR analysis of low molecular weight phosphatic metabolites.
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