Vasomotor and respiratory controlling neurons in cat caudal ventrolateral medulla

• Main Authors: Yang Kun Ta, 楊昆達
• Other Authors: Chai Chok Yung
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/82581910876534678446

碩士 === 國防醫學院 === 生理學研究所 === 87 === We examined the involvement of caudal ventrolateral medulla(CVLM) in vasomotor and respiratory control. Experiment were carried out in cats under a-chloralose/urethane anesthesia under artificial ventilation to maintain the end-expiratory CO2 at 3.5~4.5 %. Phrenic nerve activity(PNA) was recorded to monitor the changes of respiratory frequency(Rf) and inspiratory depth. Microinjection of sodium glutamate(Glu) into CVLM decreased systemic arterial blood pressure(SAP) and altered phrenic nerve activities(PNA). Among 143 depressor sites, 55 %(78/143) increased Rf, while 72 % altered inspiratory depth(36 % increased and 36 % decreased). A small but significant positive correlation was observed between the magnitudes of depressor responses and inhibition of inspiratory depth neurons. Furthermore, microinjections of acetylcholine(ACh) mimicked the Glu-induced depressor responses. However, ACh did not alter Rf, but still reduced inspiratory depth. Our findings suggest that Rf-regulating and depressor neurons are two separate neuronal population, coexisting in CVLM. The inspiratory depth inhibitory and depressor neurons, in contrast, could have stronger correlation. Inhibitory amino acid: g-aminobutyric acid(GABA) and Glycine(Gly) in the depressor/inspiratory depth-inhibition sites increased SAP while decreased inspiratory depth. GABA and Gly effects on Rf are different. Gly increased Rf, while GABA had no effect. After kainic acid lesion of Rf-increased neurons in the CVLM, the generation of PNA is severely disturbed.