Physiological salt solution - PSS

Physiological salt solution

1. Physiological salt solution Dr. Jervin

2. Introduction Need: to maintain tissue viability outside the animal body to mimic the internal environment of ions and nutrients Generally termed as Ringer solution

3. Despite over 100 years of their use in in vitro experiments most of the standard salt physiological solutions are still poor substitutes for blood.

4. Problems encountered with blood Coagulation has to be prevented. Blood is easy to oxygenate, but attempting to do this often results in problematic bubbling because of the surface active properties of proteins in the blood. Contact of blood with glass and other foreign surfaces results in the release of pharmacologically active compounds, e.g. amines (5HT) and kinins as well as the loss of platelets and other blood cells Blood is a very good nutrient for bacteria.

5. Vane Cascade EXTRACORPOREAL source of blood blood taken from a large artery used to flow over and thereby maintain isolated tissue which when used is returned via a suitable vein. This technique is the basis of the superfusion cascade assay system

6. Composition

7. role of each ingredient Na+ - major extracellular cations - maintains the electrolyte level in the tissue - makes the solution isotonic by maintaining the osmolarity K+ - major intracellular cation - important role in nerve conduction, muscle contraction,. - maintains heart rhythm CaCl2 - controls excitabilty of muscle, nerves, and glands. maintains cellular integretity , permeabilty MgCl2- 2nd most important intracellular cation reduces spontanoeus activity, role in neurtransmission HCO3- , NaHPO4 – buffer( pH7.4) glucose: major nutrient(fatty acid : cardiac muscle)

8. Variants Krebs - nerve muscle preparation - may be used for any tissue Tyrode - exp with non inervated muscle - esp mammalian smooth muscle. Frog Ringer - amphibian tissue. Ringer Locke - heart muscle preparation. DeJolan , McEwen :mammalian isolated oragan (nerve associates) and avian skeletal muscle.

9. METHODS FOR DELIVERING PHYSIOLOGICAL SOLUTION TO TISSUE Perfusion (directly connected to the vascular system) Tissue bath (sample immersed in fluid) Superfusion (solution running over the tissue surface)

10. However, oxygen solubility in water is low and thus carries little oxygen. Temperature is adjustable for homeotherms (warm blooded), room temp for poikilotherms (cold blooded). Normally the bathing temperature is kept somewhat below body temperature so as to reduce metabolic needs and so preserve tissue.

11. Precautions CaCl2 should be added at the last pH to be maintained at 7.3-7.4 Distilled water or double distilled water or deionised water is to be used Carbogen or oxygen is used for aeration error < 1%

12. Storage Fresh solution is always preferred Max storage time: 24hrs in refrigerator Risk of microbial growth : due to prescence of glucose If storage > 24hrs is required : Ca2+ and glucose is added only at the time of experiment