Uptake and retention of moulting hormones by the integument of crayfishes in vitro. II. Influence of metabolic inhibitors and sulphydryl group inhibitors.

Antimycin A and 2,4-dinitrophenol reduced both the initial uptake and the total uptake of ecdysone into crayfish hypodermis in vitro. Antimycin A did not reduce the retention of moulting hormone, in contrast to 2,4-dinitrophenol. The inhibitory effect of antimycin A could be completely overcome. The membrane-mediated ecdysteroid uptake was sensitive to the sulphydryl group inhibitors N-ethylmaleinimide (NEM) and p-chloromercuriphenylsulphonate (PCMPS). Inhibition of steroid uptake by PCMPS was completely reversed by dithiothreitol.