Opioids exert depressor effects on cardiovascular responses through sympathetic nervous system inhibition. Research suggests that opioid inhibition of sympathetic activity may be compromised in hypertension. Preliminary studies by the Principal Investigator suggest that the nature of this compromise may be influenced by age and race. Additionally, literature suggests that hypertension chronicity may modulate opioid sympathoinhibitory actions. The receptor mechanisms mediating the observed modulating effects of age, race, and hypertension chronicity on opioidergic inhibition and regulation of blood pressure remained to be determined.