MECHANISMS OF ACID-BASE TRANSPORT AND CONTROL IN LOCUST EXCRETORY SYSTEM

Recent evidence for secretion of H+ (J(H)) and ammonia (J(amm)) and co ncomitant absorption of bicarbonate and OH- in Malpighian tubules and hindgut (ileum, rectum) of desert locusts is reviewed. We include data in theses on ileal J(H), J(amm), and ammoniagenesis and evidence sugg esting their control by neuropeptides from corpus cardiacum and ventra l ganglia acting via cyclic AMP. The importance of each segment of the excretory system in acid-base elimination is estimated and compared w ith data on recovery of whole locusts from acidosis, including composi tion of the excreta. The capacity of the excretory system is more than adequate to account for the regulation of hemolymph pH in feeding loc usts injected with an acid load.