STUDIES ON THE DIURETIC HORMONE OF RHODNIUS-PROLIXUS - SOME OBSERVATIONS ON THE PURIFICATION AND NATURE OF THE HORMONE AND THE DYNAMICS OF ITS RELEASE INVITRO

The behaviour of the diuretic hormone (DH) of Rhodnius prolixus in gel filtration chromatography and electrophoresis suggests that it may be an acidic peptide. DH is insoluble in methanol, unstable to heat and low pH and is hydrolysed by proteolytic enzymes. The rate of disappearance of DH in vitro is very rapid and is influenced considerably by the extent of the surface area presented to it. An apparatus is described which permitted high K+ depolarization of large numbers of Rhodnius mesothoracic ganglia with associated abdominal nerves (MTGN) in vitro, to release the DH. Continuous and discontinuous depolarization procedures achieved very similar total hormone outputs which represented approximately 20% of the total DH store. Cold stimulation of isolated MTGN proved ineffective in releasing DH, whilst the DH released in response to treatment of isolated MTGN with ionophores could not be quantified owing to inhibition of the bioassay. © 1979.