Purchase this article with an account.
G. Fuchsjager–Mayrl, O. Markovic, S. Lung, B. Wally, G. Weigert, J. Kolodjaschna, N. Maar, M. Wolzt, L. Schmetterer; Effects of endothelin–1 on retinal, but not on choroidal blood flow, are augmented after administration of granulocyte colony stimulating factor in healthy humans . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2606.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: We have previously shown that the decrease in retinal red blood cell flow in response to systemic hyperoxia is augmented in the presence of granulocyte colony stimulating factor (G–CSF). This is most likely explained by an interaction between erythrocytes and leukocytes in the retina during vasoconstriction. In the present study we tried to verify this hypothesis by studying the effect of exogenous endothelin–1 on retinal and choroidal blood flow in the absence or presence of increased circulating leukocytes induced by administration of G–CSF. Methods: Twelve healthy male subjects partizipated in this randomized, placebo–controlled two–way cross–over study. Endothelin–1 (5 ng/kg/min over 30 minutes) was infused intravenously after pretreatment with G–CSF (300 mg) or placebo. Ocular hemodynamic parameters, blood pressure and intraocular pressure (IOP) were measured at baseline, before endothelin administration and at the end of the endothelin infusion period. Subfoveal choroidal blood flow (CHBF) was measured with laser Doppler flowmetry. Retinal red blood cell flow was calculated based on retinal vessel diameter measurements with the Zeiss retinal vessel analyser and measurements of red blood cell velocity with bi–directional laser Doppler velocimetry. Retinal white blood cell flux was assessed with the blue field entoptic system. Results: Administration of G–CSF induced a pronounced increase in retinal white blood cell density (+88 %, p < 0.001) due to the increase in circulating leukocytes. As expected endothelin–1 decreased choroidal blood flow (–11%, p < 0.001), retinal blood flow (–17%, p < 0.001) and white blood cell velocity (–8%, p = 0.007). The change in choroidal blood flow and white blood cell velocity in response to endothelin–1 was not altered by pre–treatment with G–CSF. By contrast, the decrease in retinal blood flow was significantly augmented during an increased number of circulating leukocytes (–31%, p = 0.02). Conclusions: The present data indicate that during pronounced retinal vasoconstriction red blood cell flux in the retina may depend on the number of circulating leukocytes because of an interaction of red and white blood cells in the post–capillary venules. This is not the case in the choroid, most likely related to the fact that choroidal capillaries are much wider than retinal microvessels.
This PDF is available to Subscribers Only