Journal of Applied Physiology, Vol 47, Issue 2 352-359, Copyright © 1979 by American Physiological Society
Cardiorespiratory responses following isoproterenol injection in rabbits
R. Winn, J. R. Hildebrandt and J. Hildebrandt
Receptor sites for the ventilatory response to isoproterenol were
investigated in anesthetized rabbits with bolus injections in the common
carotid artery (ia) and in the vena cava (iv). The delay from injection to
the increase in ventilation (TVE) was significantly shorter following ia
(1.5 s) compared to iv injections (about 5 s). The delay to the increase in
heart rate (THR) was significantly shorter after iv (about 4.5 s) than
after ia injections (12.5 s). When isoproterenol and NaCN injections were
compared, there was no difference in TVE. Following carotid body resection,
the VE response to isoproterenol was greatly reduced after iv and ia
injections; however, THR was unaffected. In intact animals breathing 100%
O2 the VE response to isoproterenol was significantly reduced with no
change in TVE or in the heart rate response. We conclude that the
ventilatory increase following the injection of isoproterenol is due
primarily to direct stimulation of the carotid bodies.
