TY - JOUR
T1 - Cardiac Parasympathetic Output of Nucleus Ambiguus is not Altered in Spomtaneously Hypertensive Rats
AU - Chiou, Ruei-Jen
AU - Chen, R. F.
AU - Yen, C.T.
PY - 2000
Y1 - 2000
N2 - The distribution and reactivity of cardiac parasympathetic neurons in the ventral medulla of hypertensive rats (spontaneously hypertensive rats [SHR]) and stroke-prone spontaneously hypertensive rats [SHRSP]) were compared with age matched normotensive rats (Wistar and Wistar-Kyoto [WKY]). Rats were anesthetized with alpha-chloralose and urethane. L-glutamate (Glu, 10mM, 11nl) was microinjected into the medulla to map the distribution of the cardioinhibitory neurons in and around the nucleus ambiguus (NA). The distribution pattern of the bradycardiac sites was similar in the four strains of rats. Differences in the maximal bradycardiac responses were not statistically significant either. In conparison, hypertensive rats had significantly larger depressor responses to Glu microinjected into the caudal ventrolateral medulla. Taken together, the result suggest that the ventral medulla of hypertensive ratse has enhanced sympathetic reactivity, whereas the parasympathetic cardioinhibitory mechanisms of the NA of hypertensice rats are not significantly altered. Therefore, the diminished cardiovagal response in the baroreflex of hypertensive eats may be due to an alteration on the input side.
AB - The distribution and reactivity of cardiac parasympathetic neurons in the ventral medulla of hypertensive rats (spontaneously hypertensive rats [SHR]) and stroke-prone spontaneously hypertensive rats [SHRSP]) were compared with age matched normotensive rats (Wistar and Wistar-Kyoto [WKY]). Rats were anesthetized with alpha-chloralose and urethane. L-glutamate (Glu, 10mM, 11nl) was microinjected into the medulla to map the distribution of the cardioinhibitory neurons in and around the nucleus ambiguus (NA). The distribution pattern of the bradycardiac sites was similar in the four strains of rats. Differences in the maximal bradycardiac responses were not statistically significant either. In conparison, hypertensive rats had significantly larger depressor responses to Glu microinjected into the caudal ventrolateral medulla. Taken together, the result suggest that the ventral medulla of hypertensive ratse has enhanced sympathetic reactivity, whereas the parasympathetic cardioinhibitory mechanisms of the NA of hypertensice rats are not significantly altered. Therefore, the diminished cardiovagal response in the baroreflex of hypertensive eats may be due to an alteration on the input side.
M3 - Article
VL - 11
SP - 111
EP - 125
JO - Acta Zoologica Taiwanica
JF - Acta Zoologica Taiwanica
IS - 2
ER -