Department of Ophthalmology and Optometry and Research Program for Experimental Ophthalmology, SALK/Paracelsus Medical University, Salzburg, Austria.
Invest Ophthalmol Vis Sci. 2014 Jan 21;55(1):396-403. doi: 10.1167/iovs.13-13286.
Previous experiments have shown that arginine-vasopressin (AVP) reduces intraocular pressure (IOP) dose-dependently. The present study investigated the relationships between IOP, ciliary blood flow (CilBF), and aqueous flow (AqF) responses to AVP in anesthetized rabbits.
CilBF was measured by laser Doppler flowmetry and AqF by fluorophotometry. Mean arterial pressure (MAP) and IOP were monitored continuously and simultaneously. Perfusion pressure (PP) was varied mechanically. Four experimental protocols were performed: the dose-response (n = 11) and the pressure-flow relationship (n = 8) for CilBF and the effects on CilBF, and AqF at low (0.08 ng/kg/min; n = 14) and high AVP infusion rates (1.33 ng/kg/min; n = 12).
AVP decreased CilBF and IOP dose-dependently. At the low AVP infusion rate, AqF was reduced by 21.48% ± 2.52% without changing CilBF significantly. The high AVP infusion rate caused a 24.49% ± 3.53% decrease of AqF and a significant reduction in CilBF (35.60% ± 3.58%). IOP was reduced by 9.56% ± 2.35% at low and by 41.02% ± 3.19% at high AVP infusion rates. Based on the Goldmann equation, the decrease of AqF at the low AVP infusion rate accounted for 77.1% of the IOP reduction, whereas at the high AVP infusion rate, decreased AqF accounted for 28.4% of the IOP decline.
The results indicate that AVP can modulate IOP by different dose-dependent physiological mechanisms. The shifts of the CilBF-AqF relationship suggest that the reduction of AqF by the low AVP infusion rate is mainly provoked by inhibiting secretory processes in the ciliary epithelium. In contrast, at the high AVP infusion rate, the AqF reduction is caused by either reduced CilBF or more likely by a combined effect of reduced CilBF and secretory inhibition.
先前的实验表明，精氨酸加压素（AVP）可剂量依赖性地降低眼内压（IOP）。本研究旨在探讨麻醉兔 AVP 对眼内压、睫状突血流（CilBF）和房水流出（AqF）的剂量反应关系。
采用激光多普勒血流仪测量 CilBF，采用荧光光度法测量 AqF。连续同步监测平均动脉压（MAP）和眼内压（IOP）。机械改变灌注压（PP）。进行了四项实验方案：剂量反应（n = 11）和压力-流量关系（n = 8）用于 CilBF，以及低（0.08 ng/kg/min；n = 14）和高 AVP 输注率（1.33 ng/kg/min；n = 12）对 CilBF 和 AqF 的影响。
AVP 可剂量依赖性地降低 CilBF 和眼内压。在低 AVP 输注率时，AqF 降低了 21.48%±2.52%，而 CilBF 无明显变化。高 AVP 输注率导致 AqF 降低 24.49%±3.53%，CilBF 显著降低（35.60%±3.58%）。低 AVP 输注率时 IOP 降低 9.56%±2.35%，高 AVP 输注率时 IOP 降低 41.02%±3.19%。根据 Goldmann 方程，低 AVP 输注率时 AqF 的减少占 IOP 降低的 77.1%，而高 AVP 输注率时，AqF 的减少占 IOP 下降的 28.4%。
结果表明，AVP 可以通过不同的剂量依赖性生理机制来调节 IOP。CilBF-AqF 关系的变化表明，低 AVP 输注率时 AqF 的减少主要是由抑制睫状上皮的分泌过程引起的。相比之下，在高 AVP 输注率时，AqF 的减少是由 CilBF 减少或更可能由 CilBF 减少和分泌抑制的联合作用引起的。
