Gutterman D D, Bonham A C, Arthur J M, Gebhart G F, Marcus M L, Brody M J
Department of Pharmacology, University of Iowa, Iowa City 52242.
Am J Physiol. 1989 Apr;256(4 Pt 2):H1218-27. doi: 10.1152/ajpheart.1989.256.4.H1218.
The importance of sympathetic neural influences in regulating coronary blood flow has been well established. However, central nervous system pathways responsible for these effects are largely unknown. In a feline model, we have identified a site in medullary reticular formation that may play a role in neural control of the coronary circulation. Changes in heart rate (HR), mean arterial pressure (AP), Doppler coronary flow velocity (CBFV), and femoral flow velocity (FBFV) were measured in 67 anesthetized cats. Electrical stimulation in a specific region of the right medullary lateral reticular formation produced elevations in HR (12 +/- 2% from 156 beats/min), AP (41 +/- 6% from 83 mmHg), CBFV (33 +/- 7%), and femoral vascular resistance index (136 +/- 27%). After beta-adrenergic blockade (propranolol), a transient (5-15 s) stimulus-induced decrease in CBFV was observed in 67% of animals, with a 55 +/- 6% increase in coronary vascular resistance index, not the result of autoregulation. Ipsilateral stellate ganglionectomy or systemic alpha 1-adrenergic blockade abolished the CBFV decrement. Microinjection of L-glutamate into this medullary region failed to elicit either pressor or coronary vasomotor responses. It is concluded that electrical stimulation in a specific site within medullary reticular formation produces neurogenic coronary vasoconstriction as part of a more generalized activation of central sympathetic fibers. This brain stem site may play an important role in reflex or behaviorally mediated coronary responses.
交感神经影响在调节冠状动脉血流中的重要性已得到充分证实。然而，负责这些效应的中枢神经系统通路在很大程度上尚不清楚。在一个猫模型中，我们已经确定延髓网状结构中的一个部位可能在冠状动脉循环的神经控制中起作用。在67只麻醉猫中测量了心率（HR）、平均动脉压（AP）、多普勒冠状动脉血流速度（CBFV）和股动脉血流速度（FBFV）的变化。对右侧延髓外侧网状结构的特定区域进行电刺激，可使HR升高（从156次/分钟升高12±2%）、AP升高（从83 mmHg升高41±6%）、CBFV升高（33±7%）以及股血管阻力指数升高（136±27%）。在β肾上腺素能阻断（普萘洛尔）后，67%的动物观察到刺激引起CBFV短暂（5 - 15秒）下降，冠状动脉血管阻力指数升高55±6%，这不是自动调节的结果。同侧星状神经节切除术或全身性α1肾上腺素能阻断可消除CBFV的下降。向该延髓区域微量注射L - 谷氨酸未能引发升压或冠状动脉血管舒缩反应。结论是，延髓网状结构内特定部位的电刺激会产生神经源性冠状动脉血管收缩，这是中枢交感神经纤维更广泛激活的一部分。这个脑干部位可能在反射或行为介导的冠状动脉反应中起重要作用。
