The rate limiting step for norepinephrine synthesis is:
Ans. (B) Conversion of tyrosine to DOPA(Ref: Katzung 10/e p78; KDT 8th/e p136)Rate limiting enzyme in norepinephrine synthesis is tyrosine hydroxylase that catalyses the conversion of tyrosine to dopa. In ACh synthesis, rate limiting step is uptake of choline by the neurons.