| Popis: |
The effect of intravenously injected nicardipine on retinal and optic nerve head (ONH) blood flow was studied in 27 cats using laser Doppler velocimetry and flowmetry, respectively. A dose of 20 micrograms/kg of nicardipine had little effect on retinal blood flow. A dose of 100 micrograms/kg, however, produced a significant transient decrease in flow. By contrast, both doses produced a significant increase in ONH blood flow despite a significant decrease of the mean arterial blood pressure. Measurements of the partial pressure of oxygen (PO2) with an oxygen-sensitive microelectrode, whose tip was placed in the vitreous just in front of the optic disc, showed a significant increase in the PO2 that paralleled the increase in ONH blood flow. These results demonstrate, for the first time to the authors' knowledge, a pharmacologically induced increase in ONH blood flow and suggest that nicardipine could have a beneficial effect on ONH tissue. |
