In 13 decerebrate cats, we studied the effects of captopril (10 mg/kg iv bolus) on the background discharge of thoracic preganglionic sympathetic fibers. After drug administration there was an initial reduction in systolic arterial pressure (SAP), which was followed by a later inhibition of sympathetic discharge (from 2.7 ± 0.5 to 0.79 ± 0.1 imp/0.1 s; P <0.01). Captopril significantly reduced the excitatory response of sympathetic fibers to premature ventricular contraction (70 ± 17 vs. 257 ± 30%), inferior vena cava obstruction (176 ± 56 vs. 315 ± 85%) and asphyxia (143 ± 20 vs. 245 ± 51%). Vice versa the sympathetic response to aortic occlusion was unaffected (-58 ± 8 vs. -62 ± 6%). A similar reduction in sympathetic discharge was observed after captopril administration in anesthetized cats (n = 3). On the contrary, no changes in background neural discharge were noticed in decerebrate-spinalized cats (n = 5), despite comparable hemodynamic effects. These data indicate that captopril reduces sympathetic efferent activity and its responsiveness to excitatory stimuli. The lack of neural effects in decerebrate-spinalized cats is consistent with a brain stem site of action of captopril.
|Journal||American Journal of Physiology - Heart and Circulatory Physiology|
|Issue number||2 33-2|
|Publication status||Published - 1993|
- decerebrate cats
- neural control of circulation
- spinalized cats
ASJC Scopus subject areas