Epidermal water permeation in vertebrates: an in vitro study using tritiated water.

Structural lipids play an important role in the water holding property of the skin. beta emitters are known to pass through the skin barrier. A permeability cell was constructed and tritiated water was used to determine the rate of in vitro water permeation through the epidermis. The epidermal sheets from different classes of vertebrates were compared for water permeation. Some of the samples were treated with solvents, surfactants and conditioners, to fathom permeability changes of the epidermis after these treatments, at various time intervals. Solvent treated epidermal sheets show very high degree of permeation, both in rat pup skin and pigeon skin. Glycerol, Brij 99 and beewax treated skin shows negligible permeation; or rather, helps in retention of water compared to normal and solvent treated skin. Comparison of water permeation in rat, pigeon and lizard skin shows that the reptilian integument is more efficient, as it allows very less permeation of water compared to the avian and mammalian epidermis. These observations suggest that tritiated water could be used for determining in vitro water permeation through the epidermis.

Effect of cholinesterase inhibitors on acetylcholine and insulin induced glucose uptake and certain hepatic enzymes in pigeon liver: an in vitro study.

Insulin and acetylcholine (ACh) are both known to promote glucose uptake by liver of birds. Acetylcholine induced glucose uptake can be predictably potentiated by inhibiting acetylcholinesterase activity. Monocrotophos, acothione (organophosphorus compound) and prostigmine are known inhibitors of acetylcholinesterase (AChE). In the present study the action of these three inhibitors of AChE alone as well as in combination with insulin and acetylcholine on in vitro glucose uptake by pigeon liver slices was investigated. Both organophorus compounds potentiated the action of insulin as well as acetycholine mediated glucose uptake by liver slices while prostigmine had inhibitory influence. The three compounds also induced alterations in enzyme activities in the liver slices. These results are discussed in detail in the text.

Effect of ACTH on glucose uptake by hepatic cells and its effect on hepatic enzymes in presence of insulin and acetylcholine.

An intrinsic hypoglycaemic activity has been attributed to ACTH. This action of ACTH is essentially mediated by increased insulin secretion. In the present study, the direct action of ACTH on glucose uptake by pigeon hepatocytes has been studied by in vitro technique. The results have shown that ACTH has a direct influence on glucose uptake and this action is not additive in presence of insulin. Glucose uptake in presence ACTH with Acetylcholine was not any more than what was obtained with ACTH alone. These observations have been taken to indicate a non-existence of synergistic action of ACTH with insulin or acetylcholine in promoting glucose uptake by avian liver cells.