Effects of pharmacological autonomic blockade upon cardiac rate and blood pressure conditioned and unconditioned responses in Macaca mulatta.

Heart rate, systolic and diastolic blood pressures were recorded during classical delay conditioning of rhesus macaque monkeys. When portions of the autonomic nervous system were selectively blocked by pharmacological agents, it appeared that the initial increases in heart rate and blood pressures in response to the conditioned stimulus were the result of increased sympathetic activity and a concomitant decrease in parasympathetic activity. Towards the end of the conditioned stimulus, an increase in parasympathetic activity was indicated. Blockade of the autonomic system which produced total elimination of the conditioned cardiac rate response and substantial reduction or elimination of the conditioned blood pressure response, was not necessarily or always accompanied by a corresponding elimination of the respective unconditioned responses. Such a finding suggests a different underlying neural mediation of these conditioned and unconditioned responses.