Effect of inhibitors on chloride-dependent transmural potential in the rectal wall of Schistocerca gregaria

Previous experiments in vitro revealed a transmural potential difference (PD) and a short-circuit current (Isc) across the rectal wall of Schistocerca gregaria, which were dependent on chloride ions in lumen. The present report shows that anoxia, dinitrophenol and cyanide inhibit DP and Isc, proving that the required energy derives from oxidative metabolism. Acetazolamide also inhibits DP and Isc. Ouabain, when in haemocoele, has also an inhibitory effect, not ascribable to a Na⁺K⁺ pump blocking action. It is suggested that HCO₃^? plays an important rôle in the active transport of Cl^? from lumen to haemocoele and that ouabain may in some way inhibit chloride pumping.