Eiichi Ogawa

Experimental studies on the carbonic anhydrase activity—XII: Effect of adrenocorticosteroids on carbonic anhydrase and NA+-K+-activated adenosine triphosphatase from kidney of adrenalectomized mice and rats

Abstract The effects of adrenocorticosteroids administration on renal carbonic anhydrase and Na+-K+-ATPase activities in adrenalectomized animals were investigated. In mice, carbonic anhydrase activities in homogenate, microsomal and supernatant fractions were decreased, while microsomal Na+-K+-ATPase activity was increased after adrenalectomy. In rats, the changes of both enzymic activities after adrenalectomy were reverse to those observed in mice. These changes in carbonic anhydrase activity after adrenalectomy were restored to normal levels with aldosterone and DOCA replacement, but corticosterone and cortisol had no effect on its enzymic activity in both animal species. The elevation in Na+-K+-ATPase activity after adrenalectomy in mice was restored with DOCA and cortisol, but aldosterone had no effect on enzymic activity. The decline in Na+-K+-ATPase activity after adrenalectomy in rats was prevented and approached the normal levels with replacement of both mineralo- and glucocorticoids. From above results it became clear that the adrenocorticosteroids have a role in maintaining normal levels of renal enzymic activities.

Effects of aldosterone, actinomycin D, puromycin and cycloheximide on RNA synthesis, carbonic anhydrase and atpase activities of the kidney and on urinary excretion of sodium in adrenalectomized mice

Abstract Aldosterone (2 μg/kg) administered to adrenalectomized mice increased the synthesis of RNA from [6-14C]-orotic acid in the kidney and increased the carbonic anhydrase activity but not the microsomal ATPase activity. However, urinary excretion of sodium was decreased 2–4 h after aldosterone administration. Aldosterone increased the specific radioactivity of RNA, but not the overall content of RNA in the kidney. The increase in specific radioactivity is primarily a nuclear RNA. The increase in carbonic anhydrase activity and decrease of urinary excretion of sodium produced by aldosterone were inhibited by actinomycin D (300 μg/kg), puromycin (60 mg/kg) and cycloheximide (1 mg/kg). These findings are consistent with the so called “induction hypothesis”—that is aldosterone would have its major effect in the nucleus, resulting in increased synthesis of RNA and ultimately in increased synthesis of specific enzymes. The results of this study indicate the possibility that kidney carbonic anhydrase may be a mediator of the action of aldosterone on tubular reabsorption of sodium in adrenalectomized mice.

Experimental studies on the carbonic anhydrase activity—XV: Early effect of aldosterone and actinomycin D on carbonic anhydrase and adenosine triphosphatase in normal and adrenalectomized rats

Abstract Effect of the single administration of aldosterone and actinomycin D on the activities of carbonic anhydrase in kidney and liver and of ATPase in kidney microsomes was examined with normal and adrenalectomized rats. In normal rats, both aldosterone and actinomycin D alone inhibited kidney carbonic anhydrase activity and a minimum value was obtained in 4–6 hr after treatment. (Na + -K + -Mg 2+ )- and Mg 2+ -ATPase activities were not affected by either drug. Aldosterone and a smaller dose of actinomycin D had a stimulatory effect, while a larger dose of actinomycin D showed an inhibitory effect on liver carbonic anhydrase activity. Adrenalectomy produced an elevation in carbonic anhydrase activity of the kidney and liver and a decrease in (Na + -K + -Mg 2+ )-ATPase activity. Administration of aldosterone depressed the elevated carbonic anhydrase activity to normal level without any effect on ATPase activity. Although actinomycin D had no effect on carbonic anhydrase activity from kidney and liver of adrenalectomized rats; in aldosteronepretreated adrenalectomized rats, actinomycin D inhibited carbonic anhydrase activity as in normal rats. Actinomycin D had an inhibitory effect on (Na + -K + -Mg 2+ )-ATPase activity in adrenalectomized and aldosterone-nontreated rats.

Experimental studies on the carbonic anhydrase activity—XIV: Effect of aldosterone and actinomycin D in vitro on carbonic anhydrase from liver and kidney of mice

Abstract After incubating kidney and liver slices in Krebs-Ringer phosphate solution with or without aldosterone, actinomycin D and cortisol, carbonic anhydrase activity in 77,000 g supernatant fraction was examined. In the kidney, aldosterone increased and actinomycin D decreased the enzymic activity, while cortisol had no effect. In the liver, aldosterone and a smaller dose of actinomycin D increased, while cortisol decreased the enzymic activity. The elevation of renal carbonic anhydrase activity after aldosterone treatment was blocked by the concurrent addition of actinomycin D. The depression of renal carbonic anhydrase activity and the elevation of hepatic carbonic anhydrase activity after actinomycin D treatment were blocked by the concurrent addition of aldosterone. Smaller doses of aldosterone and actinomycin D were added directly to kidney and liver homogenates and the changes in enzymic activity were examined. Kidney carbonic anhydrase activity was increased by aldosterone and decreased by actinomycin D. Liver enzymic activity was increased by aldosterone and a smaller dose of actinomycin D, although neither drug had a direct effect on the activities of renal and hepatic carbonic anhydrase in 700 g supernatant, 77,000 g precipitate and 77,000 g supernatant fractions.