Nellore Kavitha, Harris Norman R
Department of Bioengineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Microcirculation. 2004 Jul-Aug;11(5):415-23. doi: 10.1080/10739680490457809.
Arteriolar tone is partially controlled by diffusing mediators released by closely paired venules and is reported to depend on venular shear and venular leukocyte adherence. In healthy rat mesentery, venule-initiated arteriolar dilation and consequent enhanced capillary flow appear to be tightly regulated by nitric oxide (NO). In contrast, diabetes inhibits NO-dependent vasodilation and is associated with dysfunctional microcirculation. The objective of this study was to investigate venule-dependent NO in diabetes.
Arteriolar and venular wall concentrations of NO were measured in control and diabetic (streptozotocin-induced) rat mesentery with fluorescent diaminofluorescein-2-diacetate (DAF-2-DA); tissue NO was measured with DAF-2. Venular leukocyte adherence and microvascular shear rates were also measured.
Microvascular NO in diabetic rats was found to be significantly lower (<50%) than in controls. In normal rats, arteriolar NO demonstrated a positive correlation with venular NO and venular shear, and a negative correlation with venular leukocyte adherence. Diabetes eliminated all these correlations. No correlation was present between arteriolar NO and arteriolar shear in either normal or diabetic rats.
Arteriolar NO appears to be enhanced by venular shear in normal but not in diabetic rats. This dysfunction could contribute to poor capillary perfusion in diabetes.
小动脉张力部分受紧密相邻的小静脉释放的扩散介质控制，据报道其依赖于小静脉切应力和小静脉白细胞黏附。在健康大鼠肠系膜中，小静脉引发的小动脉扩张及随之增强的毛细血管血流似乎受一氧化氮（NO）严格调控。相比之下，糖尿病会抑制依赖NO的血管舒张，并与微循环功能障碍相关。本研究的目的是探究糖尿病中小静脉依赖的NO情况。
用荧光二氨基荧光素-2-二乙酸酯（DAF-2-DA）测量对照和糖尿病（链脲佐菌素诱导）大鼠肠系膜中小动脉和小静脉壁的NO浓度；用DAF-2测量组织NO。还测量了小静脉白细胞黏附和微血管切变率。
发现糖尿病大鼠的微血管NO显著低于对照组（<50%）。在正常大鼠中，小动脉NO与小静脉NO和小静脉切应力呈正相关，与小静脉白细胞黏附呈负相关。糖尿病消除了所有这些相关性。在正常或糖尿病大鼠中，小动脉NO与小动脉切应力之间均无相关性。
在正常大鼠而非糖尿病大鼠中，小静脉切应力似乎会增强小动脉NO。这种功能障碍可能导致糖尿病患者毛细血管灌注不良。
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