Anderson P A, Fair E C, Nassar R, Gorman A J, Killam A P
Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710.
Pediatr Res. 1994 May;35(5):550-4.
The inhibitory hemodynamic effects of the Bezold-Jarisch reflex in the adult animal, which play a role in the response to disease states, are elicited by veratridine and are mediated by vagal afferents. We tested whether the reported excitatory response to veratridine in the fetal animal may be caused by a maturational phase in the Bezold-Jarisch response. The effects of proprananol and atropine on the hemodynamic response to veratridine were examined at 124-141 d (mean, 133 d) of gestation in 11 fetal lambs instrumented long-term (instrumentation, 111-129 d of gestation). Seven lambs had intact vagal nerves, and four had bilateral cervical vagotomies. Veratridine injected into the superior vena cava (0.3 to 2.8 micrograms/kg) and the left atrium (0.2 to 0.8 microgram/kg) increased heart rate, arterial pressure, and left ventricular output, with the responses to left atrial injections occurring more rapidly. Propranolol markedly inhibited the increase in arterial pressure; atropine had no effect. Neither carbocaine, perfused around the cervical vagi, nor bilateral transection of the vagal nerves altered the hemodynamic excitatory response to veratridine. These findings demonstrate that the fetal excitatory response to veratridine is not mediated by vagal afferents, indicating the Bezold-Jarisch reflex does not undergo a maturational change from an excitatory reflex to an inhibitory one and suggesting the maturational loss of a sympathetically mediated hemodynamic reflex.
贝佐尔德-雅里什反射在成年动物中具有抑制性血流动力学效应，该效应在对疾病状态的反应中起作用，由藜芦碱引发并由迷走神经传入介导。我们测试了在胎儿动物中报道的对藜芦碱的兴奋性反应是否可能由贝佐尔德-雅里什反应的成熟阶段引起。在11只长期植入仪器（植入时间为妊娠111 - 129天）的妊娠124 - 141天（平均133天）的胎羊中，研究了普萘洛尔和阿托品对藜芦碱血流动力学反应的影响。7只羔羊迷走神经完整，4只进行了双侧颈迷走神经切断术。向上腔静脉注射藜芦碱（0.3至2.8微克/千克）和向左心房注射藜芦碱（0.2至0.8微克/千克）会增加心率、动脉压和左心室输出量，对左心房注射的反应出现得更快。普萘洛尔显著抑制动脉压升高；阿托品无作用。无论是在颈迷走神经周围灌注卡波卡因，还是双侧切断迷走神经，都未改变对藜芦碱的血流动力学兴奋性反应。这些发现表明，胎儿对藜芦碱的兴奋性反应不是由迷走神经传入介导的，这表明贝佐尔德-雅里什反射不会经历从兴奋性反射到抑制性反射的成熟变化，并提示存在一种由交感神经介导的血流动力学反射的成熟丧失。
