Effects of different drugs on isolated intestine

1. Effects of different drugs on isolated intestine

2. Experimental purpose • To master the experiment condition of isolated intestinal smooth muscle and effects of different drugs on them; • To master the fundamental method of designing drug interaction and to improve the designment ability by observing the relationship between Barium Chloride and receptors

3. Gastrointestinal tract (Smooth muscle)

4. Experimental animals • Mice jejunoileum

5. Experimental drugs • 10-4 mol/L Isoprenaline Hydrochloride • 10-4 mol/L Propranolol Hydrochloride • 10-3 mol/L Acetylcholine Hydrochloride • 10-3 mol/L Atropine Sulfate • 10-3 mol/L Verapamil • 2% Barium Chloride

6. Experimental apparatus • RM6240 signal acquisition and processing system; Magnus experimental facility (include Magnus tube, thermostatic waterbath, almighty bracket and so on) ; Tonotransducer; Air pump; Surgical instruments and syringes, et al.

7. Experimenta principles • Intestinal innervation include adrenergic nerves and cholinergic nerves, and the latter plays a leading role. Intestinal receptors include M- cholinergic receptors, β- adrenergic receptors and a small quantity of α- adrenergic receptors, whose stimulation or inhibition can make intestine contract or relax.

8. Experimenta principles • To stimulate M- cholinergic receptors can induce intestine contraction, and to block them induce intestine relaxation. On the contrary, to stimulate β- adrenergic receptors induce intestine relaxation, and to block them induce intestine contraction. All of the above effects ultimately depend on Ca2+ channel opening or closure.

9. Sequence of administration first second • Action weak strong • Mechanism clear unclear • Receptor agonist antagonist agonist

10. Experimental method and procedure • Group discussion to design optimal sequence of administration; • Preparation of experimental facility: Wash the Magnus tube; Turn on the thermostatic waterbath and set tempreture at about 37℃; Turn on the computer; Hang the 1g counterweight and make the baseline rise about 2 big lattices .

11. Experimental method and procedure • Preparation of intestinal samples: Fetch a mouse and sacrifice it by dislocation of cervical vertebra; Open the abdomen immediately and find the enterocinetic intestines; Cut the jejunoileum into 1 to 2cm pieces and put them in cold Krebs’ solution for future use.

12. Experimental method and procedure • Fixing samples: Wash your hands and dip some nutrient fluid on your finger tips; Fetch a piece of intestinal samples and tie a thread at each end; Fix the sample, bung the Magnus tube with rubber stopper, pour enough nutrient fluid into the Magnus tube and adjust the length of the thread to make the baseline rise about 1 big lattice; Turn on air pump, set the velocity at 1 to 2 bubbles each second; Trace a length of normal curve.

13. Experimental method and procedure • The dosage of each drug is 0.1ml, and another 0.1ml can be added if the effect is not obvious enough. • Analyze and discuss the experimental results, finish the test report.

14. Attention • The experiment should be carried out under the suitable condition and gas should be supplied continuously; • The manipulation should be light and soft to keep activity of intestine; • Add the drug over the liquid surface and never underneath it.

15. Questions • Intestinal innervation and their effects; Intestinal receptor distribution and different effects by stimulating or blocking them. • The fundamental principles of designing sequence of administration. • How can you observe that the contraction of intestines is based on Ca2+?