Riquelme Raquel A, Sánchez Gina, Liberona Leonel, Sanhueza Emilia M, Giussani Dino A, Blanco Carlos E, Hanson Mark A, Llanos Aníbal J
Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
J Physiol. 2002 Oct 1;544(Pt 1):267-76. doi: 10.1113/jphysiol.2002.018325.
The hypothesis that nitric oxide plays a key role in the regulation of adrenal blood flow and plasma concentrations of cortisol and catecholamines under basal and hypoxaemic conditions in the llama fetus was tested. At 0.6-0.8 of gestation, 11 llama fetuses were surgically prepared for long-term recording under anaesthesia with vascular and amniotic catheters. Following recovery all fetuses underwent an experimental protocol based on 1 h of normoxaemia, 1 h of hypoxaemia and 1 h of recovery. In nine fetuses, the protocol occurred during fetal I.V. infusion with saline and in five fetuses during fetal I.V. treatment with the nitric oxide synthase inhibitor L-NAME. Adrenal blood flow was determined by the radiolabelled microsphere method during each of the experimental periods during saline infusion and treatment with L-NAME. Treatment with L-NAME during normoxaemia led to a marked fall in adrenal blood flow and a pronounced increase in plasma catecholamine concentrations, but it did not affect plasma ACTH or cortisol levels. In saline-infused fetuses, acute hypoxaemia elicited an increase in adrenal blood flow and in plasma ACTH, cortisol, adrenaline and noradrenaline concentrations. Treatment with L-NAME did not affect the increase in fetal plasma ACTH, but prevented the increments in adrenal blood flow and in plasma cortisol and adrenaline concentrations during hypoxaemia in the llama fetus. In contrast, L-NAME further enhanced the increase in fetal plasma noradrenaline. These data support the hypothesis that nitric oxide has important roles in the regulation of adrenal blood flow and adrenal corticomedullary functions during normoxaemia and hypoxaemia functions in the late gestation llama fetus.
对一氧化氮在羊驼胎儿基础和低氧条件下调节肾上腺血流以及皮质醇和儿茶酚胺血浆浓度中起关键作用这一假说进行了验证。在妊娠0.6 - 0.8时，对11只羊驼胎儿进行手术准备，在麻醉状态下通过血管和羊膜导管进行长期记录。恢复后，所有胎儿都经历了一个实验方案，包括1小时的常氧血症、1小时的低氧血症和1小时的恢复。在9只胎儿中，该方案在胎儿静脉输注生理盐水期间进行，在5只胎儿中在胎儿静脉注射一氧化氮合酶抑制剂L - NAME期间进行。在生理盐水输注和L - NAME治疗的每个实验期间，通过放射性微球法测定肾上腺血流。常氧血症期间用L - NAME治疗导致肾上腺血流显著下降，血浆儿茶酚胺浓度明显升高，但不影响血浆促肾上腺皮质激素（ACTH）或皮质醇水平。在输注生理盐水的胎儿中，急性低氧血症引起肾上腺血流以及血浆ACTH、皮质醇、肾上腺素和去甲肾上腺素浓度增加。用L - NAME治疗不影响胎儿血浆ACTH的增加，但阻止了羊驼胎儿低氧血症期间肾上腺血流以及血浆皮质醇和肾上腺素浓度的增加。相比之下，L - NAME进一步增强了胎儿血浆去甲肾上腺素的增加。这些数据支持了一氧化氮在妊娠晚期羊驼胎儿常氧血症和低氧血症期间调节肾上腺血流和肾上腺皮质髓质功能中起重要作用这一假说。
