Shazmi Khan.
Receptor Affinity of Opioids used to affect Painless Delivery.
Mother & Child Jan ;37(1):1-18.

The presence of kappa receptors was explored with pentazocine in the presence of buprenorphine. Buprenorphine did not reverse the decrease in heart rate while naloxone reversed the decrease in heart rate produced by pentazocine. It is, concluded that although opioid receptors are present in isolated rabbit heart but they are not of kappa subtype. They are present on myocardial cells where they exerts some subcellular action. The decrease in heart rate by the pentazocine in the presence of adrenaline induced chronotropy appears to have some protective effect on heart.

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