Isolation and purification of the diuretic hormone from Rhodnius prolixus

Extracts of Rhodnius prolixus mesothoracic ganglionic masses were subjected to column chromatographic separation procedures. The eluates were assayed biologically for diuretic hormone activity.Gel filtration through columns of polyacrylamide gel was found to separate soluble diuretic activity into two distinct zones. Poor recovery was obtained with respect to the activity of the crude extract. No diuretic activity was found to co-chromatograph with a sample of 5-hydroxytryptamine. When samples of haemolymph from freshly fed Rhodnius were chromatographed under similar conditions only the second zone (low molecular weight) was found to have diuretic activity. It is this low molecular weight zone which would more reasonably qualify as the physiologically active diuretic hormone. Likewise, the diuretic activity released from isolated mesothoracic ganglionic masses by K⁺-rich Ringer's solution showed only low molecular weight activity after chromatography.