TY - JOUR
T1 - Reflex cardiovascular changes with veratridine in the conscious dog
AU - Barron, K. W.
AU - Bishop, V. S.
PY - 1982
Y1 - 1982
N2 - The present study was undertaken to examine the reflex responses of activation of cardiac sensory receptors in the conscious dog. Intracoronary (left circumflex coronary artery) injection of veratridine (0.10 μg/kg) reduced mean arterial pressure (-40 mmHg, P < 0.05), heart rate (-34 beats/min, P < 0.05), and maximum rate of rise of left ventricular pressure (LV dP/dt(max)) (-419 mmHg/s, P < 0.05). Bilateral cervical vagal cold block (BVB) eliminated the depressor and bradycardic responses of veratridine. BVB not only eliminated the negative inotropic response to veratridine but reversed it to a positive inotropic response (LV dP/dt(max) increased 313 ± 76 mmHg/s). Ganglionic blockade abolished all effects of veratridine. The bradycardia and negative inotropic effects caused by veratridine were attenuated by either atropine or metoprolol and completely eliminated by the combination of the two antagonists. Veratridine also produced a decrease in renal artery blood flow but had no effect on renal vascular resistance. In contrast, iliac blood flow was increased with veratridine, and this, combined with the depressor effect, resulted in a decrease in iliac vascular resistance (-37%, P < 0.05). BVB abolished the changes in renal and iliac blood flow or resistance caused by veratridine. The results indicate that activation of cardiac receptors in the conscious dog elicits inhibitory reflexes to the heart and peripheral circulation that are mediated by vagal afferents. After vagotomy, veratridine elicited a reflex positive inotropic response, which may have resulted from activation of cardiac sympathetic afferent fibers.
AB - The present study was undertaken to examine the reflex responses of activation of cardiac sensory receptors in the conscious dog. Intracoronary (left circumflex coronary artery) injection of veratridine (0.10 μg/kg) reduced mean arterial pressure (-40 mmHg, P < 0.05), heart rate (-34 beats/min, P < 0.05), and maximum rate of rise of left ventricular pressure (LV dP/dt(max)) (-419 mmHg/s, P < 0.05). Bilateral cervical vagal cold block (BVB) eliminated the depressor and bradycardic responses of veratridine. BVB not only eliminated the negative inotropic response to veratridine but reversed it to a positive inotropic response (LV dP/dt(max) increased 313 ± 76 mmHg/s). Ganglionic blockade abolished all effects of veratridine. The bradycardia and negative inotropic effects caused by veratridine were attenuated by either atropine or metoprolol and completely eliminated by the combination of the two antagonists. Veratridine also produced a decrease in renal artery blood flow but had no effect on renal vascular resistance. In contrast, iliac blood flow was increased with veratridine, and this, combined with the depressor effect, resulted in a decrease in iliac vascular resistance (-37%, P < 0.05). BVB abolished the changes in renal and iliac blood flow or resistance caused by veratridine. The results indicate that activation of cardiac receptors in the conscious dog elicits inhibitory reflexes to the heart and peripheral circulation that are mediated by vagal afferents. After vagotomy, veratridine elicited a reflex positive inotropic response, which may have resulted from activation of cardiac sympathetic afferent fibers.
UR - http://www.scopus.com/inward/record.url?scp=18844483113&partnerID=8YFLogxK
U2 - 10.1152/ajpheart.1982.242.5.h810
DO - 10.1152/ajpheart.1982.242.5.h810
M3 - Article
C2 - 7081453
AN - SCOPUS:18844483113
SN - 0363-6135
VL - 11
SP - H810-H817
JO - American Journal of Physiology - Heart and Circulatory Physiology
JF - American Journal of Physiology - Heart and Circulatory Physiology
IS - 5
ER -