1. Effect of Certain Agonists & Their Antagonists on The Isolated Rabbit Intestine
Lab #3

2. Stimulants & their Blockers 1-Drugs act on Nn R
Agonist
Dil. Nicotine (0.01%, 0.1ml)
MOA: Dil. Nicotine stimulates Gs protein in cell membrane
→ activates Na-K channels
→ ↑ intracellular Na
→ rapid depolarization
→ contraction
Antagonist
Conc. Nicotine (0.1%, 0.1ml)
Conc. Nicotine is depolarizing ganglionic blocker
MOA: it causes an initial depolarization (↑cont.)
followed by successive depolarization
→ transmission failure & muscular fatigue

3. Stimulants & their Blockers 2-Drugs act on M3 R
Agonist
Ach (0.01%, 0.1ml)
MOA :Ach stimulate of Gs protein activate M3 R activation of PLC
→ Splitting of (PIP2) into:
1- DAG → ↑opening of Calcium channels
2- IP3 → mobilization of cal. from its stores
↑ intracellular calcium→contraction
Antagonist
Atropine (0.1ml, 0.1%)
It is a specific, nonselective, reversible, competitive blocker of M3 R

4. Determining the site of action of unknown
Blocker +
Agonist
Unknown
Unknown
Agonist
Without washing