Lohrmann and Kamemoto (16) and Sommer and Mantel (33) have reported, respectively, that in the crabs, C. sapidw and C. muenas, branchial **Na influx is rapidly changed by injected dopamine, pericardial organ extracts and dibutry1 cyclic AMP, a cyclic AMP analog which is more permeable
than CAMP in the cell membrane. Sommer and Mantel (32) also reported increased branchial Na, KATPase ESA with injected CAMP and, in a second study, showed that branchial cyclic AMP concentrations were increased by low-salinity stress (33). Recent work also suggests that crab branchial Na, K-ATPase ESA may be controlled by gill tissue concentrations of polyamines. Although these developments are interesting, much work must be done to identify and characterize both short- and long-term control systems for ion transport in the crustacean gill. In this regard it is of interest that Schwarz and Graszynski (30) have developed a split-lamella, Ussingtype gill preparation, which is proving to be useful in the in vitro study of the mechanisms and physiological control of ion transport in crab gills (21). Riestenpatt et al. (25) have found that cyclic AMP stimulates sodium uptake in split crab gill lamellae from freshwater-acclimated E. sinensis by increasing apical sodium channel number and apical
sodium conductance. Thus, both the apical and basolateral transport of sodium seem to be under physiological control.
Lohrmann and Kamemoto (16) and Sommer and Mantel (33) have reported, respectively, that in the crabs, C. sapidw and C. muenas, branchial **Na influx is rapidly changed by injected dopamine, pericardial organ extracts and dibutry1 cyclic AMP, a cyclic AMP analog which is more permeablethan CAMP in the cell membrane. Sommer and Mantel (32) also reported increased branchial Na, KATPase ESA with injected CAMP and, in a second study, showed that branchial cyclic AMP concentrations were increased by low-salinity stress (33). Recent work also suggests that crab branchial Na, K-ATPase ESA may be controlled by gill tissue concentrations of polyamines. Although these developments are interesting, much work must be done to identify and characterize both short- and long-term control systems for ion transport in the crustacean gill. In this regard it is of interest that Schwarz and Graszynski (30) have developed a split-lamella, Ussingtype gill preparation, which is proving to be useful in the in vitro study of the mechanisms and physiological control of ion transport in crab gills (21). Riestenpatt et al. (25) have found that cyclic AMP stimulates sodium uptake in split crab gill lamellae from freshwater-acclimated E. sinensis by increasing apical sodium channel number and apicalsodium conductance. Thus, both the apical and basolateral transport of sodium seem to be under physiological control.
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