EVIDENCE FOR PROCTOLIN AND A 2ND MYOTROPIC PEPTIDE IN THE COCKROACH, LEUCOPHAEA-MADERAE, DETERMINED BY BIOASSAY AND HPLC ANALYSIS

Purification and analytical HPLC methods were developed for quantitatively determining proctolin in extracts of foreguts, hindguts, and heads of Leucophaea maderae. The system will measure as little as 30 ng of proctolin from extracts containing up to 50 organs. Comparison of analytical results with bioassay data indicates that all of the myogenic activity in these foregut and hindgut extracts can be accounted for by proctolin (0.83 ng/foregut, 3.3 ng/hindgut). Proctolin was absent from head extracts but these extracts contained another myogenically active peptide, the hindgut-stimulating neurohormone. Proctolin and neurohormone caused an increase in the frequency, amplitude, tonus and coordination of contractions of the hindgut. Both peptides produced a protracted excitation of the hindgut. Both proctolin at 3 × 10-10 M and HSN at 0.5 head equivalents/ml evoked responses that lasted for 65 min before the preparations were rinsed in fresh saline solution. © 1979.