Changes in the diuretic and antidiuretic properties of the hemolymph during the six-day vitellogenic cycle in the American cockroach

Abstract

The “antidiuretic principle” concentration in the hemolymph of Periplaneta americana (L.) is low during the initial period of the six-day vitellogenic cycle. On the fourth day the concentration begins to rise and reaches a maximum on the fifth and sixth days of the cycle. The diuretic factor remains relatively constant except on day three when a peak is seen. However, the increase in “antidiuretic principle” on days 4,5, and 6 may mask a similar rise of diuretic activity. It is postulated that the physiological role of the antidiuretic principle is in conservation of water to counteract the tremendous water loss via the eggs. However, the possibility that the principle is actually a smooth-muscle stimulating hormone which enhances the movement of the eggs down the oviduct cannot be ruled out. There may be two components involved with each one having overlapping functions.