Question

The same neurotransmitter has 2 different action in two different cellular locations; what can be the possible mechanisms?

Answer 1

The different action is due to the what receptor they bind.

Example.

The effects of acetylcholine on the heart and on the skeletal muscles.

A. Acetylcholine slows the rhythmic contraction of heart by causing slow hyper polarization of catdiac muscle.

• Acetylcholine in the heart , a metabotropic , Acetylcholine receptor is coupled by G- Protein to a potassium channel.
• The opening of K+ channel hypeepolarize the cardiac muscle fibees and it reduce the rate at which it fires action potential.

B. In skeletal muscle, Acetylcholine induces contraction by causing a rapid depolarization of the muscle fibers.

• In the skeletal muscles ,the receptors is a transmitter - gated ion channel.
• Specifically an acetylcholine gated ion channel permeable to Na+ .
• Te opening of this channel depolarize the muscle fibers and makes them more excitable.