Willis A P, Leffler C W
Laboratory for Research in Neonatal Physiology, Departments of Physiology and of Pediatrics, University of Tennessee, Memphis, Tennessee 38163, USA.
Am J Physiol. 1999 Jul;277(1):H299-307. doi: 10.1152/ajpheart.1999.277.1.H299.
Responses to hypercapnia and acetylcholine by newborn piglet pial arterioles are prostanoid dependent but appear to require both prostanoids and nitric oxide in juvenile pigs. We hypothesized that cerebrovascular dilatory responses become less prostanoid dependent and more NO dependent with development. Pial arteriolar responses to hypercapnia and histamine were recorded from alpha-chloralose-anesthetized newborn and juvenile pigs with closed cranial windows. Responses were recorded during control, after indomethacin or N(omega)-nitro-L-arginine (L-NNA), and after inhibitor plus iloprost or sodium nitroprusside. Indomethacin blocked newborn hypercapnic responses and markedly attenuated histamine dilations, but only reduced the dilations to about half in juveniles. Iloprost at subdilator concentrations restored newborn responses to hypercapnia and histamine but did not alter either response in indomethacin-treated juveniles. L-NNA attenuated juvenile, but not newborn, hypercapnia-induced dilations. Sodium nitroprusside did not restore the response. L-NNA did not alter responses to histamine in either age group. Cerebrovascular dilations to hypercapnia and histamine are prostanoid dependent and nitric oxide independent in the newborn pig, whereas nitric oxide assumes an increasing role in hypercapnic, but not histamine, responses with development.
新生仔猪软脑膜小动脉对高碳酸血症和乙酰胆碱的反应依赖于前列腺素，但在幼年猪中似乎需要前列腺素和一氧化氮两者。我们假设脑血管舒张反应随着发育变得对前列腺素的依赖性降低，而对一氧化氮的依赖性增加。在α-氯醛糖麻醉、开有闭合颅窗的新生和幼年猪中记录软脑膜小动脉对高碳酸血症和组胺的反应。在对照期间、吲哚美辛或N（ω）-硝基-L-精氨酸（L-NNA）处理后以及抑制剂加伊洛前列素或硝普钠处理后记录反应。吲哚美辛阻断了新生猪的高碳酸血症反应并显著减弱组胺引起的舒张，但仅将幼年猪的舒张减少到约一半。亚舒张浓度的伊洛前列素恢复了新生猪对高碳酸血症和组胺的反应，但对吲哚美辛处理的幼年猪的两种反应均无改变。L-NNA减弱了幼年猪而非新生猪由高碳酸血症引起的舒张。硝普钠未恢复该反应。L-NNA在两个年龄组中均未改变对组胺的反应。新生猪中脑血管对高碳酸血症和组胺的舒张依赖于前列腺素且不依赖于一氧化氮，而随着发育，一氧化氮在高碳酸血症反应中起越来越大的作用，但在组胺反应中并非如此。
