EFFECT OF IONS PERFUSET HEART OF FROG

 

EFFECT OF IONS PERFUSET HEART OF FROG

 

Aim: To isolate frog’s heart and to study the effect of variousions

 

Requires: Recording instructions. Perfusion funnel, Syme’s cannula perfusion fluid. Sodium Chloride, potassium chloride and calcium chloride solutions.

 

Speed of the drum: Slow speed with gear and pulleys S4 – D1.

 

Procedure: Perfusion of frog’s heart: The .heart of the pithed frog is exposed and the pericardium is removed. A thread is passed beneath the inferior venacave. A small opening is made on the ventral side of the inferior vanacav and blood is completely washed out using perfusing fluid.

               

                The nozzle of the cannuala is in inserted through the opening of the inferior venacave till the tip of the cannula reaches the sinus venosus. Now the venacave is tied to the cannula with the thread. Then .by holding the cannuala and by keeping the index finger at the nozzle of the cannualaand by keeping the index finger at the nozzle of the cannuala along with the inferior venacave. The other structures are, removed from the heart.

 

                The cannuala with the heart is fized to the clamp attached to the myograph stand. The horizontal limb of the cannuala is connected by means of rubber tube to the perfusion tunnel which is also fixed to the myograph stand by clamp and the perfasion fluid from the funnel is allowed to pass through’ the heart.

 

                The bent hook is passed through the tip of the ventricle, and the head of this bent pin is tied with the thread which is also tied to the stariling’s level fized to the myograph stand for this experiment the lever is fixed up side down.

 

2) Study of effects of ions: First the normal cardiogram is recorded. Few drops of 1% sodium chloride solution is added through cannuala and the effect is recorded. Then the solution in the cannuala is washed out and normal cardiogram is recorded ‘similarly the effects of 1%. potassium chloride and 1% calcium solution are recorded.

 

Observations:

1. Effect of sodium chloride sodium ions first exit the cardiac tissue and then the rate and force of contraction are increased later the sodium chloride causes increase in amplitude and stoppage of heart in diastole.
2. Effect of potassium chloride the potassium ions relax the heart and the heart stops in diastole immediately.
3. Effect of the calcium chloride when calcium chloride is added the force of contraction gradually increases and the heart stops in systole which is called the calcium rigor the calcium rigor is irreversible one.

Inference

 

1) Composition of perfusion fluid

 

a) Sodium chloride              ………………………0.650 gm%

b) Calcium Chloride            ………………………0.0 12 gm%

c) Potassium Chloride         ………………………0.014 gm %

d) Sodium bicarbonte         ………………………0.010 gm %

e) Sodium phosphate          ………………………0.001 gm %

 

2) Mode of action of ions:

                The excess of sodium ions depresses the cardiac function as the sodium ions complete with calcium ions which are necessary for causing the action potential and contraction of the muscle. The potassium ions also cause the heart to become dilated but the reason is different from the action of sodium the excess of potassium ions decreases, the resting membrane potential. As the resting membrane potential decreases, the intensity of the action potential are decreases, which Makes the contraction of heart to become progressively, weaker. The calcium ions cause the exactly opposite effects of sodium and potassium ions. The calcium makes the heart to go into spastic contraction by exciting the cardiac contraction contractile process.