High temporal resolution coupling of low-flow push-pull perfusion to capillaryelectrophoresis for ascorbate analysis at the rat vitreoretinal interface

摘要

A system is presented demonstrating the high-temporal resolution coupling of low-flow push-pullperfusion sampling (LFPS) to capillary electrophoresis for the absorbance measurement of ascorbate atthe rat vitreoretinal interface. This system holds all separation components at a low pressure as themeans for withdrawing sample during LFPS. The system uses a flow-gated interface to directly couplethe withdrawal capillary from the LFPS probe to a separation capillary and eliminates the need for anyoffline sample handling. The temporal resolution of the system was limited by injection time and is lessthan 16 s. This high temporal resolution was applied to the monitoring of in vivo ascorbate levels at therat vitreoretinal interface. Baseline concentrations of ascorbate were found to be 86 μM + 18μM at thevitreoretinal interface. Baseline concentrations matched well with those obtained for the postmortembulk vitreous analysis. Upon stimulation with 145 mM K~+, a maximum increase in baseline valuesbetween 32-107% for n = 3 was observed. This system demonstrates the first in vivo temporal study ofascorbate at the rat vitreoretinal interface.