Muscle rigidity by fentanyl is due to which receptor:

Ans. (a) Meu (m)Ref.: Millers Anaesthesia 7th ed. / 914Opioid receptors are of four variety - mu (m), Kappa (k), delta (d) & sigma (s)ReceptorClinical effectAgonist (m2)Muscle rigidityPhysical dependenceSupraspinal analgesiaRespiratory depressionFentanylMorphineb- EndorphinMu (m) (m2)Kappa (k)SedationSpinal analgesiaMorphineNalbuphineDynorphin (endogenous opioid)Butorphanol oxycodoneDelta (d)AnalgesiaBehavioralEpileptogenicLeu - Enkephalinb- EndorphinSigma (s)DysphoriaHallucinationRespiratory stimulationPentazocineNalorphineKetamine