Henrion D, Bevan J A
Department of Pharmacology, University of Vermont, College of Medicine, Burlington.
J Vasc Res. 1995 Jan-Feb;32(1):41-8. doi: 10.1159/000159076.
Intraluminal flow can cause both dilation or constriction of small arteries, depending on the level of tone. Both responses are specifically modulated in the same way by small changes in extracellular Na+ ([Na+]e). We have investigated the effect of changes in [Na+]e on the level of contraction induced by a standard flow of physiological salt solution in ring of segments of the rabbit facial vein and on the associated 45Ca2+ influx and net uptake. Decreasing [Na+]e by 20% reduced the response to flow by 58%, and increasing it by 20% augmented the flow response by the same extent. There is a linear relationship between the level of the flow-induced contraction and [Na+]e over the range 120-180 mM. An alteration in [Na+]e of 10 mM corresponds to a 20% change in flow-induced contraction. This relationship is quantitatively the same as that previously reported for the rabbit ear resistance artery [10]. Histamine (1 microM)-induced tone was not affected by changes in [Na+]e within the range 75-180 mM. 45Ca2+ influx and net uptake per unit force developed in response to flow were unaffected by these changes in [Na+]e. The flow-induced contraction of the vein was selectively, in comparison to that due to histamine, attenuated by amiloride, methyl-isobutyl-amiloride and monensin. It is argued that the observation that flow-induced contraction, caused by small alterations in extracellular sodium concentration, is not associated with changes in calcium uptake per unit force is consistent with an extracellular flow sensor.(ABSTRACT TRUNCATED AT 250 WORDS)
管腔内血流可导致小动脉扩张或收缩，这取决于血管张力水平。细胞外钠离子浓度（[Na⁺]e）的微小变化会以相同方式特异性调节这两种反应。我们研究了[Na⁺]e变化对兔面静脉段环中生理盐溶液标准流量诱导的收缩水平、相关的⁴⁵Ca²⁺内流和净摄取的影响。将[Na⁺]e降低20%可使血流反应降低58%，将其升高20%则使血流反应增强相同程度。在120 - 180 mM范围内，血流诱导的收缩水平与[Na⁺]e之间存在线性关系。[Na⁺]e改变10 mM相当于血流诱导收缩变化20%。这种关系在数量上与先前报道的兔耳阻力动脉相同。组胺（1 μM）诱导的张力在75 - 180 mM范围内不受[Na⁺]e变化的影响。这些[Na⁺]e变化不影响每单位力产生的⁴⁵Ca²⁺内流和净摄取。与组胺引起的收缩相比，静脉的血流诱导收缩可被阿米洛利、甲基异丁基阿米洛利和莫能菌素选择性减弱。有人认为，细胞外钠浓度的微小变化引起的血流诱导收缩与每单位力钙摄取变化无关，这一观察结果与细胞外流传感器一致。（摘要截断于250字）
