The Effect of Pitressin and Pitocin on Water Balance in Bufo Regularis Reuss

Abstract

1. In Bufo regularis the injection of either pitressin or pitocin is followed by an increase in the rate of water absorption through the skin, together with a marked decrease in urine flow. The response to pitressin is greater than that to pitocin. 2. The effect of pitocin in increasing water uptake can be attributed to the activity of the 5-10% of the pressor fraction which it contains. 3. A mixture of pitressin and pitocin has the same effect on water balance as a corresponding dose of pituitrin. Pitressin alone has a greater anti-diuretic effect than it has when pitocin is added. 4. Taking into account the antagonistic action of pitocin to pitressin it is possible to account for the anti-diuretic action of pitocin in terms of its pressor fraction content. 5. It is concluded that the pressor fraction is the main factor responsible for both the dermal and the renal components of the water-balance effect produced in B. regularis by injection of mammalian posterior pituitary extracts. This conclusion is discussed in relation to the findings of other workers.