Inspiratory activity on the left and right sides must be coordinated to be effective. We used cross-correlation to examine the hypothesis that the coordination of left and right medullary inspiratory neurones is produced by excitation from common sources and by midline-crossing excitatory connections among these neurones. In adult rats, a total of 185 contralateral pairs of inspiratory neurones (n=370) were recorded extracellularly, and classified, according to their firing pattern, as augmenting (n=262), constant (n=82) or decrementing (n=26). Of the 262 augmenting inspiratory neurones, 98 were classified as phrenic premotor neurones by cross-correlation with phrenic nerve discharge. The 185 cross-correlograms showed little evidence of common activation, or midline-crossing excitatory connections. Of the 45 cross-correlograms for pairs of augmenting neurones, only 4 (≅9%) indicated a common activation, and only one a monosynaptic connection. Of the 45 for pairs of augmenting and phrenic premotor neurones, only 9 (20%) showed a common activation, and only 2 a monosynaptic excitatory connection. Of the 19 pairs of phrenic premotor neurones, 5 from the same rat showed high-frequency oscillations, and 1 a monosynaptic excitatory connection. Cross-correlograms for pair combinations of other types of neurones also exhibited few features. We suggest that, in the adult rat, although both common activation and excitatory cross-connections exexist as a means for coordinating left and right ventral group inspiratory neurones to the same respiratory rhythm, they are insufficient to account for it.

This study was to observe the changes of the neuronal and inducible nitric oxidesynthase(nNOS ＆ iNOS) as well as their mRNAs in the rostral ventrolateral mudulla(RVLM) of stress-induced hypertensive rats before and after acupuncture, and thereby to infer the curative mechanism of acupuncture on hypertension. The result indicated that the systolic blood pressure(SBP) of stress group rats was increased significantly(P＜0.01), it was accompanied that the expression of nNOS in the RVLM, including the immunoreactive neuron number(P＜0.05), the optical density(OD)(P＜0.01), and the mRNA(P＜0.01) were obviously elevated, while those of iNOS(P＜0.05, P＜0.01 and P＜0.01) were evidently lowered in the stress-induced hypertensive rats. Electroacupuncture(EA) points at "Zusanli" (St.36) and "Lanwei"(Extra 37) on the same hindlimb were stimulated by an EA apparatus(Type G6805-2) with dense sparse wave(4-20Hz) and 4mA intensity. EA application could return the SBP(P＜0.05), and the changes on the expression of both nNOS and iNOS(P＜0.05, P＜0.01 and P＜0.01). These results suggest that the curative mechanism of acupuncture on stress-induced hypertension is related to the changes of nNOS and iNOS in the RVLM of rats

In the transverse medullary slice prepared from neonatal rats the hypoglossal nerve rootlets exhibit a bursting 'respiratory' rhythm as do neurones in the pre-B

目的　研究嘌呤能受体(purinergic receptors,P2) 家族中P2X 不同亚型在新生和成年SD大鼠延髓的表达。方法　成年SD大鼠(6-8w) 和新生SD大鼠(1-5d)，各6只,雌雄不计，取延髓。应用免疫组织化学的方法和图像分析技术，比较P2X2和P2X4受体在新生和成年SD大鼠延髓的表达。结果　P2X2和P2X4嘌呤受体的阳性神经元和阳性纤维在新生鼠和成年鼠的延髓都有广泛表达，主要分布在孤束核、Ⅻ颅神经核和延髓腹外侧区，延髓其他区域为散在的分布。成年鼠和新生鼠的P2X2受体均比P2X4受体表达水平高。在新生鼠髓,P2X2 和P2X4的表达水平均比成年鼠低。结论　P2X2 和P2X4阳性神经元和阳性纤维广泛分布在大鼠延髓,为ATP对心血管活动、呼吸活动和痛觉等的调节作用提供了结合位点,也有利于实验中P2X受体亚型阻断剂的选择。随着动物发育成熟,P2X2和P2X4表达水平均增加。