Effects of N omega-nitro-L-arginine on total and segmental vascular resistances in developing lamb lungs.
Effects of N omega-nitro-L-arginine on total and segmental vascular resistances in developing lamb lungs.
复制标题
N omega-硝基-L-精氨酸对发育中的羔羊肺的总和节段血管阻力的影响。
DOI：
10.1152/jappl.1993.75.1.76
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
Tod,ML
中科院分区：
文献类型：
--
作者：
Gordon,JB;Tod,ML
为了确定内皮衍生的硝酸甘油(EDNO)是否像扩张剂前列腺素一样，比年长的新生儿更能减弱肺血管运动张力，我们观察了一氧化氮合酶抑制剂N omega-硝基-L-精氨酸(L-NA)对环氧合酶抑制的2日龄(2D)和1月龄(1M)羔羊肺总阻力和节段性肺血管阻力的影响。总PVR由稳态压力-流量曲线和恒定流量(100mL.kg-1xmin-1)下测量的总压阶差(增量PT)确定。通过流入-流出阻塞确定动脉段(Delta Pa)、中段(Delta Pm)和静脉段(Delta Pv)的压力梯度。在1M肺(n=6)，常氧和低氧时，L-NA使增量PT、增量Pa值和增量Pv升高。然而，只有在低氧时，Delta Pm才增加，这表明EDNO在高音时对小血管阻力的减弱作用更大。在2D肺中，L-NA的反应是不同的。在4个“应答者”(2D“R”)中，L-NA治疗后，常氧和缺氧性Delta PT及所有节段阻力均显著增加，而在5个“无应答者”(2D“NR”)中，L-NA对Delta PT的影响不显著。此外，2D“NR”肺的对照Delta PT值高于2D“R”肺，这表明一些年轻新生儿的基础EDNO活性很低。尽管如此，EDNO似乎可以减弱新生儿的静脉阻力，因为L-NA增加了所有组的增量PV。在一些年轻新生儿中，EDNO对PVR的调节减弱的意义和机制(S)仍有待确定。
To determine whether endothelium-derived nitic oxide (EDNO), like dilator prostaglandins, attenuates pulmonary vasomotor tone more in younger than in older newborns, we examined the effects of a nitric oxide synthase inhibitor, N omega-nitro-L-arginine (L-NA), on total and segmental pulmonary vascular resistance (PVR) in isolated blood-perfused cyclooxygenase-inhibited lungs of < 2-day-old (2D) and 1-mo-old (1M) lambs. Total PVR was determined both from steady-state pressure-flow curves and total pressure gradients (delta PT) measured at constant flow (100 ml.kg-1 x min-1). Pressure gradients across arterial (delta Pa), middle (delta Pm), and venous (delta Pv) segments were determined by inflow-outflow occlusion. In 1M lungs (n = 6), L-NA increased delta PT, delta Pa, and delta Pv during normoxia and hypoxia. However, delta Pm increased only during hypoxia, suggesting that EDNO attenuates resistance of small vessels more when tone is high. The response to L-NA in 2D lungs was variable. In four "responders" (2D"R"), normoxic and hypoxic delta PT and all segmental resistances increased markedly after L-NA, but in five "nonresponders" (2D"NR"), L-NA had an insignificant effect on delta PT. Moreover, control delta PT values were higher in 2D"NR" than in 2D"R" lungs, suggesting that basal EDNO activity was minimal in some young newborns. Nonetheless, EDNO appears to attenuate venous resistance in newborns, because L-NA increased delta Pv in all groups. The significance of and mechanism(s) responsible for lesser modulation of PVR by EDNO in some young newborns remain to be determined.