Kidneys Of Adrenalectomized Rats Research Articles

The binding of 18-hydroxydeoxycorticosterone and 18-hydroxycorticosterone to mineralocorticoid and glucocorticoid receptors in the rat kidney.

Possible roles—physiological or pathological—for the adrenal steroids 18-OH-deoxycorticosterone (18-0H-D0C) and 18-OH-corticosterone (18-OH-B) are of wide current interest. Although no direct proof of such roles for these steroids has been established, they have been implicated in inappropriate salt retention and in some forms of hypertension. The initial step in the action of all steroid hormones studied to date appears to be the binding of the steroid to a cytoplasmic receptor in target tissue. This study examines the possibility that these 18-OH-steroids may act by binding to mineralocorticoid (Type I) or glucocorticoid (Types II and III) receptors in kidneys of adrenalectomized rats. Competitive binding assays have been used to estimate the affinity of the 18-OH-steroids relative to either aldosterone (Type I) or corticosterone (Types II and III) for the three classes of receptors. Previously determined Kdiss values of aldosterone or corticosterone are used to calculate Kdiss values of the 18-OH-stero...

Glucocorticoid receptors in rat kidney: the binding of tritiated-dexamethasone.

The effects of glucocorticoid hormones are thought to be initiated by binding to stereospecific intracellular receptor proteins in target tissues. The kidney enjoys a variety of functions influenced by glucocorticoid hormones. High affinity glucocorticoid receptors have been demonstrated in adrenalectomized rat kidney by the specific binding of dexamethasone (DM). These receptors have been designated Type II, and can be distinguished from high affinity mineralocorticoid receptors (Type I) and the CBGlike corticosterone receptors (Type III) on the basis of differing affinities for a series of physiological and synthetic steroids. By Scatchard plot analysis, the equilibrium (dissociation) constant of the 3HDM–cytoplasmic receptor complex was 5 X 10-9M (25 C), and the concentration of binding sites 1.6 X 10-13 moles per mg protein in the cytoplasmic high speed supernatant (HSS). Similar concentrations of receptor were found in outer cortex and medulla—papilla. The affinity of the Type—II receptor for steroid...

In vitro stimulation of gluconeogenesis from pyruvate and of 14CO 2-fixation by dexamethasone phosphate and vasopressin in the kidney cortex of adrenalectomized rats

Dexamethasone phosphate and vasopressin stimulate glucose synthesis and 14CO 2-fixation of adrenalectomized rat kidney cortex explants in vitro . 3′,5′-cyclic-AMP demonstrates similar effects as vasopressin. In contrast to dexamethasone phosphate, vasopressin and 3′,5′-cyclic-AMP act without any lag phase. Their stimulatory effects are additive to that of the adrenal steroid. All hormonal effects are suppressed by cycloheximide. The implications of these results concerning different mechanisms of action for the adrenal steroid and vasopressin (or 3′,5′-cyclic-AMP) will be discussed.

Effect of mineralocorticoid agonists and antagonists on binding of 3H-aldosterone to adrenalectomized rat kidney plasma membranes

Binding of 3H-aldosterone to plasma membranes of adrenalectomized rat kidney has been demonstrated in vivo and in vitro . Steroids with mineralocorticoid activity, deoxycorticosterone or 9-α-fluorohydrocortisone (agonists), or aldosterone antagonists (spironolactone, progesterone) markedly reduced the binding of 3H-aldosterone to renal plasma membranes. Steroids without agonist or antagonist properties (testosterone, 17-β-estradiol) were not effective. The 3H-aldosterone-membrane complex was resistent to solubilization and subsequent chromatography employing Sephadex G-25. These experiments indicate that binding of 3H-aldosterone to adrenalectomized rat kidney plasma membranes may be involved in the cellular mode of action of aldosterone.

Ascorbic acid metabolism in adrenalectomized rats

Male albino rats were adrenalectomized and their ascorbic acid, dehydroascorbic acid, and diketogulonic acid were determined in liver and urine, while only the total ascorbic acid was determined in blood, at the intervals of 4, 8, and 12 days after adrenalectomy. Activities of ascorbic acid synthesizing enzyme d-glucurono-δ-lactone hydrolase, l-gulono-γ-lactone hydrolase, and l-gulono-γ-lactone oxidase were estimated in liver. The activities of ascorbic acid degrading enzymes dehydroascorbatase and 2,3 diketoaldonate decarbozylase were studied in liver and kidney. In adrenalectomized rats there was a slight decrease in the ascorbic acid level and an appreciable decrease in dehydroascorbic acid content of the liver. On the other hand, there was about two-fold increase in the diketogulonic acid content of liver. The content of ascorbic acid and dehydroascorbic acid in the urine of adrenalectomized rats decreased significantly, while there was slight increase in the diketogulonic acid content. There was also a slight decrease in total ascorbic acid content of blood. Decreases of about 20% and 30% were observed in the activities of d-glucurono-δ-lactone hydrolase and l-gulono-γ-lactone oxidase respectively, while the activity of l-gulono-γ-lactone hydrolase remained practically unchanged. An appreciable increase in the activity of dehydroascorbatase and a moderate increase in the activity of diketoaldonate decarboxylase were observed in liver and kidney of adrenalectomized rats. All corresponding alterations were more conspicuous in rats 12 days after adrenalectomy.

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

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.

Regulation of the (Na + + K +)-activated ATP hydrolyzing enzyme system in rat kidney II. The effect of aldosterone on the activity in kidneys of adrenalectomized rats

1. 1. The aim of the study has been to examined the effect of aldosterone in vivo on the activity of (Na + + K +)-ATPase (ouabain sensitive; ATP phosphshydrolase, EC 3.6.1.3) in kidneys of adrenalectomized rats. 2. 2. Repeated injections of aldosterone increased the activity of (Na + + K +-ATPase in the microsomal fraction from whole kidneys after 14 and 24 h. In this period corticosterone had no effect on activity of the enzyme, while combinations of aldosterone and corticosterone caused a significant increase in activity. After 48 h, corticosterone restored the activity to normal levels, while aldosterone at best increased the activity to a level midway between the activity of adrenalectomized and of normal rats. 3. 3. In an attempt to localize an effect of aldosterone, the activity of (Na + + K +-ATPase was measured in preparations from subdivisions of the kidneys. Aldosterone in physiological doses (0.25 μg, 2.5 μg, and 5.0 μg per 100 g rat 4. every 4.5 h for 24 h produced a significant increase in activity in the outer medulla where the ascending limbs of Henle predominate. In the inner cortex an increase in activity was observed after treatment with the two higher doses of aldosterone, while only insignificant changes were found in the outer cortex. The rise in activity was gradual and first detectable after more than 6 h of treatment. 4. 4. The results are compatible with an adaptation of the level of (Na + + K +-ATPase to the sustained increase in reabsorption of sodium following repeated injections of aldosterone to adrenalectomized rats.

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

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 glucocorticoids and insulin on 3',5'-AMP phosphodiesterase activity in adrenalectomized rats.

Glucocorticoids stimulate the rate of lipolysis which is reduced in adrenalectomized animals. This hormonal action is antagonized by insulin. The antilipolytic action of insulin appears to be mediated by a reduced intracellular concentration of 3′,5′-AMP. This reduction can partly be attributed to an insulin-induced acceleration of 3′,5′-AMP degradation. — It is shown that the stimulatory influence of glucocorticoids on lipolysis is due to a reduction of 3′,5′-AMP phosphodiesterase (PDE) activity, which is increased by adrenalectomy. PDE activity was also increased in liver, skeletal muscle and kidney of adrenalectomized rats; treatment with a glucoeorticoid prevented this increase.In vitro, PDE purified from beef heart was inhibited by glucocorticoids in high concentrations (Ki=1.1 · 10−3 M for 6 α-methylprednisolone hemisuccinate,K i=1.6 · 10−3 M for prednisolone succinate).In vivo, the glucocorticoid-induced decrease of PDE activity (with retarded onset as shown in liver), may essentially be attributed to a decreased enzyme synthesis. — Studies on the interaction of insulin and glucocorticoids on PDE activity were performed in the liver. In adrenalectomized, alloxan diabetic rats insulin stimulated PDE activity suppressed by treatment with a glucoeorticoid, unsuppressed PDE activity was not increased by insulin. In contrast, the action of glucocorticoids on PDE activity was independent of the presence or the effectiveness of insulin.

The effect of aldosterone and cortisocterone on the (Na++ K+)‐activated ATP hydrolyzing enzyme system in kidneys of adrenalectomized rats

The effect of aldosterone and cortisocterone on the (Na⁺+ K⁺)‐activated ATP hydrolyzing enzyme system in kidneys of adrenalectomized rats

Aldosterone-induced RNA synthesis in the adrenalectomized rat kidney

1. 1. RNA synthesis induced by a single intravenous dose of aldosterone in rat kidney was characterized by differential thermal phenol extraction, a procedure which partially separates transfer, ribosomal and messenger RNA. 2. 2. Aldosterone stimulates the incorporation of [ 14C]orotic acid into RNA fractions obtained at all temperatures. 3. 3. Stimulated incorporation was observed at 30 and 60 min after administration of aldosterone. 2–3 h after aldosterone administration, the incorporation of [ 14C]orotic acid into RNA was again approaching control levels. 4. 4. Gradient density analysis showed consistent aldosterone stimulation in the 28-, 18- and 4-S peaks of RNA. 5. 5. Phenylbutazone, a nonsteroidal antinatriuretic agent, did not appear to stimulate the incorporation of [ 14C]orotic acid into RNA.

Effect of adrenalectomy on amino acid incorporation into protein by cell-free preparation from liver and kidney of rats at various time after the operation

Amino acid incorporation into protein by liver ribonucleoprotein particles and kidney microsomes, obtained from normal and adrenalectomized rats, was investigated. The liver and kidney particles were prepared at various times, ranging from 3 h to 31 days after adrenalectomy. The 14C-incorporating activity of liver particles from adrenalectomized rats was greater than that observed with particles from liver of normal animals up to 15 days after adrenalectomy; at 21 and 31 days after the operation the liver particles showed an activity 60 and 80 %, respectively, of that of the control group. Microsomes from kidney of adrenalectomized rats demonstrated an incorporating activity higher than that of the microsomes from kidney of normal animals at all the times investigated; a sharp increase was observed at 21 and 31 days after adrenalectomy, when the activity of the liver particles was low. A correlation was established between incorporating activity of liver and kidney particles; to an increase or decrease in the activity of the particles from the liver corresponded a decrease or an increase, respectively, in the activity of the kidney microsomes. The 14C-incorporating activity of both liver and kidney particles was directly proportional to the ratio of μg RNA to mg protein in these particles up to 15 days after adrenalectomy, deviations occurring at more prolonged time after the operation.

Glucose-6-phosphate dehydrogenase and renin in kidneys of hypertensive or adrenalectomized rats.

Using a histochemical method, moderately strong glucose-6-phosphate dehydrogenase activity can be demonstrated in the macula densa of the distal tubules in the normal rat kidney. In rats rendered hypertensive by overdosage with cortexone (DOC) and saline, this enzymatic activity was found to decrease almost to zero within 4 weeks. This change was more marked in unilaterally nephrectomized animals than in intact rats. Measured by bioassay, the renin content of kidney extracts from the same animals was found to decrease simultaneously with the loss of enzymatic activity in the macula cells. The reverse effect, a marked increase in activity of the macula densa, was obtained in adrenalectomized animals. It is suggested that both the macula densa cells and the juxtaglomerular apparatus are parts of a system which respond similarly to changes in sodium balance and which may be related to the formation of renin.