Myogenic contractions in locust muscle induced by proctolin and by wasp philanthus triangulum venom
Piek, T.; Mantel, P.
Journal of Insect Physiology 23(3): 321-326
Myogenic slow contractions of the extensor tibiae of Locusta migratoria can be induced by proctolin [from Periplaneta americana proctodaeum] in a concentration of 10-10 to 10-9 mol/l perfusion fluid. Proctolin in a concentration of 10-8 mol/l causes a prolonged contraction interrupted by rhythmical relaxations. Higher concentrations of proctolin cause a powerful but irreversible contraction. In some preparations in which proctolin is ineffective in a concentration of 10-9 mol/l, a short stimulation of nerve 3b can initiate a series of rhythmic contractions. If nerve 3b is stimulated at the peak of such a contraction a rapid relaxation is induced. Administration of the venom of P. triangulum in a concentration which blocks the excitatory and inhibitory neuromuscular transmission, induces similar myogenic contractions. Stimulation of nerve 3b at the peak of such a contraction again causes a relaxation. Similar myogenic contractions can also be induced by administration of locust homogenate.