Effect Of Eserine On The Action Of Acetyl Choline On Frog Rectus Muscle

Aim

To determine the action of eserine on the action of Acetyl Choline on the frog rectus

Apparatus

Recording Drum or Kymograph Stand with lever Bent glass tube Frog dissection instruments

Procedure

A pitched frog dissected and rectus abdominis exposed Lower end is fastened to bent glass tube Muscle immersed in beaker containing ringer Two normal contractions are recorded with interval of 3 min Eserine is added to medium and amplitude of contraction is

observed

Observation

Observations are recorded on recording drum and interpreted

Inference

Eserine potentiates the effect of Acetylcholine on muscle It inhibits both true and pseudo cholinesterase Causes accumulation of choline at motor end plate and

hence increased amplitude of contraction

Effect Of d-Tubocurarine On The Action Of Acetyl Choline On Frog Rectus Muscle

Aim

To know the effects of d-Tubocurarine on Acetylcholine contractions of frog rectus muscle

Apparatus

Kymograph or Recording drum Frog dissection instruments Oxygen tube Aerator Simple lever

Solutions

Frog ringer solution ( Nacl : 9gm, Kcl : 0.42 gm, Cacl2 : 0.24gm, NaHCo3 :0.5 gm, Distilled Water : 1.4 lit

Acetylcholine 1microgram/ml d-Tubocurarine 2 microgram/ml

Dissection

A pitched frog is laid on a plate. Skin of the abdominal wall is cut and open. Identify the horizontal ladder like fibrous bands of rectus

abdominis muscle. Separate both muscles from the abdominal wall. Pass threads underneath the muscle. Tie the upper ends and lower ends.

Swipe off the upper end with a piece of xiphisternum and lower end with pubic attachment.

The muscle with threads is kept in a beaker with lower end is tied to the oxygen tube and upper end to the simple lever.

It has a counter weight or load of 1.4gm using plasticine. A beaker of ringer solution is kept under the oxygen tube and

oxygen is allowed to pass. Leave the preparation for half an hour. Put sufficient load so that the contractions will be able to raise the

lever

Dissection

Procedure

The drum is started and is allowed to rotate for 15 sec After 15 sec, the ringer solution is changed with Acetylcholine solution. After 90 sec, it is replaced with frog ringer solution. The muscle that contracts during Ach exposure, slowly relaxes and

comes to original position Repeat the process until you get equal contractions with Ach. Now immerse the muscle in d-Tc solution for 30 sec Replace with Ach and repeat contractions If 10 micrograms of d-Tc is given, complete depression of Ach

contraction is seen

Observation

Stimulatory action of Ach on rectus abdominis muscle Blocking action of curare or d-Tc on Ach induced

contractions of rectus muscle