Correlation of Cardiovascular and Respiratory Responses to Glutamate Excitation of Pressor Areas of the Medulla in Cats

C. K. Su ； S. Y. Chen ； J. M. Yang ； R. H. Lin ； H. T. Horng ； J. C. Hwang ； C. Y. Chai

《The Chinese Journal of Physiology》 35卷4期 (1992/12) Pp. 279-289

並列摘要

Su, C.K., S.Y. Chen, J.M. Yang, R.H. Lin, H.T. Horng, J.C. Hwang, and C.Y. Chai, Correlation of Cardiovascular and respiratory responses to glutamate excitation of pressor areas of the medulla in cats. Chinese J. Physiol. 35(4): 279-289, 1992. Cardiorespiratory responses, including changes of systmic arterial pressure (SAP), renal or splanchnic sympathetic nerve activity (SNA) and phrenic nerve activity (PNA), were elicited by microinjection of monosodium glutamate solution (0.5M, 100nl) into the dorsal (DM) and rostral ventrolateral medulla (RVLM) in 15 vagotomized cats anesthetized by urethane-chloralose and paralyzed by gallamine triethiodide. Artificial ventilation was adjusted to keep the end-tidal CO2 concentration at 4.0-0.5%. Sixty two pressor and 17 non-pressor sites were stimulated. Most of the stimulations inhibited the PNA. The response of SNA was variable, showing increases, decreases or no change. Inhibition of SNA during SAP increase was not secondary to baroreceptor activation as the inhibition persisted in carotid sinus/aortic denervated animals. Although variouis combinations of changes of SNA and PNA were observed, their temporal courses were similar in many instances. Attenuation of SNA and PNA was synchronized, suggesting that these changes are coupled in the stimulating sites. The findings suggest that some neurons in DM and RVLM act as a functional unit to modulate cardiorespiratory functions whereas others simply coexist in the same area independent from each other.

並列關鍵字

phrenic nerve activity ； sympathetic nerve activity ； pressor responses ； dorsal medulla ； ventrolateral medulla