Action of steroids on H+ and NH+4 excretion in the toad urinary bladder

This study was done to determine if steroid compounds will stimulate the urinary bladder of the toad to increase its capacity to acidify the urine and excrete NH+4. Aldosterone, 17 beta-estradiol, dexamethasone, pregnenolone, and cholesterol were tested on the bladder. All compounds tested were found to stimulate the rate of acidification by the bladder, above that of a paired control hemibladder. In contrast, only the steroids aldosterone and 17 beta-estradiol were found to stimulate NH+4 excretion in the bladder. Cycloheximide was found to block the action of aldosterone on the NH+4 excretion, but did not have a significant effect on the stimulation of acidification by aldosterone. We conclude that steroids stimulate H+ and NH+4 excretion in the toad urinary bladder. In addition, the NH+4 excretory system seems to be more specific to this effect than is the H+ excretory system.