Which action is attributed to aldosterone

A water container with The concentration of plasma aldosterone was measured by radioimmunoassay RIA. Plasma was mixed with diethylether fold the volume , shaken for 30 min, staying at room temperature for 15 min and quickly frozen in a mixture of acetone and dry ice. The organic phase was collected, dried, and reconstituted by 0.

Decanted the supernatant, cells were further incubated with 0. At the end of the incubation, 0. After incubation with or without the appropriate stimulant, ZG cells were washed twice with ice-cold saline and then harvested in 50 ml of cell lysis buffer 1. The cytoplasmic protein concentration in the supernatants was determined by the protein-dye method of Bradford [27] , using BSA as a standard.

The next incubation was performed with a rabbit monoclonal antibody against rabbit StAR and Pscc. The antibody of StAR was kindly provided by De.

Stocco Dept. Cell Biol. Health Sci. The antibody of Pscc was purchased from Chemicon International, Inc. The protein expression was quantified by scanning densitometry [28] , [29] , [30]. In the present RIA system, a known amount of unlabeled aldosterone, an aliquot of plasma extract or medium samples, adjusted to a total volume of 0.

Duplicate standard curves with five points ranging from 3 to pg of aldosterone were included in each assay. An adequate amount 0. The inhibition curves produced by ether-extracted rat plasma and the incubation medium of rat ZG cells were parallel to those given by unlabelled aldosterone.

The concentrations of corticosterone in rat plasma or medium of zona fasciculate-reticularis ZER were measured by RIA as previously described [31] , [32]. The anti-corticosterone antiserum PSW was provided by Dr. The intra- and inter-assay coefficients of variation were 3.

The intra- and inter-assay coefficients of variation were 6. The intra- and inter-assay coefficiencies of variant CV were 5. The treatment means were tested for homogeneity using the two-way ANOVA, and the difference between specific means was tested for significance using Duncan's multiple-range test. Data from the in vivo experiments were analyzed by Student's paired and unpaired t -tests. A difference between two means was considered statistically significant when P was less than 0.

Plasma ACTH levels in rats were enhanced by 4. There was no significant difference in Tmax of plasma corticosterone between swimming and water immersion groups Table 2. Plasma glucose levels showed no change after lactate and pyruvate infusion Fig. Plasma lactate Fig. Intravenous infusions of either pyruvate or lactate for 10 min did not alter the secretion of ACTH Fig.

Plasma Ang II showed no change after lactate and pyruvate infusion Fig. Lactate at 1—10 mM resulted in no change on aldosterone production by rat ZG cells Fig. To determine whether the effects of lactate on ZG cells were correlated to the altered StAR or Pscc protein expressions, the levels of these proteins in ZG cells were assessed by Western blotting and densitometry.

Lactate at the concentrations of 2. Administration of lactate did not alter the expressions of Pscc protein in rat ZG cells data not shown. Our previous studies have demonstrated that the increased plasma testosterone levels in male rats during exercise are at least a result of a direct and LH-independent stimulatory effect of lactate on the secretion of testosterone by the Leydig cells in rat testicular tissues [35] , [36].

In the present study, plasma lactate and aldosterone levels were significantly increased after 10 min swimming. Although the plasma aldosterone had a little increase after water immersion at 10 min, the increased folds were not significantly higher than the basal value and the swimming group. These results suggest that swimming is capable of stimulating glucose metabolism and zona glomerulosa cell releasing aldosterone.

Since the levels of plasma ACTH and corticosterone were enhanced by either swimming or water immersion Fig. Moreover, the maximum responses of plasma ACTH and corticosterone were faster or earlier and greater in swimming group than in water immersion group Fig.

However, the above responses or summation effect of exercise and stress did not happen in the secretion of aldosterone and Ang II, because the levels of plasma aldosterone Fig. It is a coincidence that previous studies have also evidenced that exercise can lead to aldosterone secretion [14] , [37] , [38].

We had detected the levels of plasma ACTH and plasma corticosterone, where the stress hormones were secreted from anterior pituitary and adrenal cortex, respectively, and found that swimming for 10 min in male rats resulted in an increase of plasma ACTH and plasma corticosterone level by 4. Whereas the enhancements of plasma ACTH and plasma corticosterone doubled in male rats during water immersion. The reason why a mild increase occurred in plasma ACTH and corticosterone after intravenous infusion of pyruvate or lactate was not clear.

Since these patterns of hormonal response were different from those in water immersion and swimming groups Fig. It seems that the increase of plasma glucose concentrations during swimming or exercise was at least in part due to the increased secretion of stress hormones, e.

At the same time, Ang II also increases after 10 min exercise, it is apparent that the stimulatory effects of aldosterone release might be related to the renin-angiotensin-aldosterone system. Although the arterial blood pressure was not detected in rats during swimming, the rise of arterial blood pressure should be expected in the present study. The increased level of plasma sodium during swimming might be one of the contributors to the enhanced arterial blood pressure.

During exercise, both blood volume and blood flow decreased to reduce glomerular filtration rate and then to increase osmolality [10]. The juxtaglomerular cells of kidney release the enzyme renin. Renin activates angiotensinogen, converting it into angiotensin I and then Ang II under the action of converting enzyme. Ang II causes blood vessels to constrict and increases aldosterone production. Aldosterone increases the reabsorption of both sodium and water as well as the excretion of potassium from the kidneys, which increases blood volume and therefore increases blood pressure to supply tissue oxygen.

The present results also showed an increase of plasma osmolality and sodium, and a decrease of potassium after 10 min exercise. Since the rise of plasma sodium and the decrease of plasma potassium were different from the increased pattern of plasma aldosterone, other factors in addition to aldosterone might be involved in the regulation of sodium retention, potassium excretion and plasma osmolality during swimming or exercise.

In addition, lactate infusion for 10 min also raised plasma aldosterone and lactate levels. However, the increased fold was not higher than or equal to the levels in the swimming group, thus, lactate might contribute only in part to aldosterone production. Other mechanisms might be involved in the stimulatory effects of exercise on the production of aldosterone. The present results suggest that both exercise- and lactate-infusion-induced increases of plasma aldosterone concentration were coexistent with the increase in plasma lactate.

Because of sodium lactate or sodium pyruvate infusion, plasma sodium level was significantly higher to increase plasma osmolality. Therefore, we suggested that the increase in osmolality was due to high plasma sodium levels. Since lactate infusion increases plasma aldosterone levels in this study and aldosterone is majorly released from adrenal gland, so a further study was designed to investigate if there is a direct stimulatory effect of lactate on adrenal gland which leads to an increased aldosterone production.

Therefore, ZG cells were incubated with lactate. Since the physiological levels of lactate in rat plasma are within a range of 2—10 mM, the effective doses of lactate utilized in vitro in the present study are involved in the normal and exercise physiological statuses. During the 60 min incubation, lactate had no direct effect on aldosterone production in ZG cells.

However, administration of lactate e. It has been well known that Ang II is an effective stimulant for aldosterone secretion both in vivo and in vitro [24] , [25] , [26].

When Ang II combined with lactate treatment at the exercise level 10 mM , ZG cells released more aldosterone to keep body fluid. Thus, lactate plays an important role to stimulate aldosterone release during exercise.

Kellerman RD, et al. In: Conn's Current Therapy Elsevier; Accessed Sept. Ferri FF. Aldosteronism hyperaldosteronism, primary. In: Ferri's Clinical Advisor Feehally J, et al. Endocrine causes of hypertension — Aldosteronism. In: Comprehensive Clinical Nephrology. Funder JW, et al. The management of primary aldosteronism: Case detection, diagnosis, and treatment: An Endocrine Society clinical practice guideline.

The Journal of Clinical Endocrinology and Metabolism. Lee FT, et al. Evaluation and management of primary hyperaldosteronism. Surgical Clinics of North America. Hundemer G. Aldosterone is part of a group of linked hormones, which form the renin— angiotensin —aldosterone system. Activation of this system occurs when there is decrease in blood flow to the kidneys following loss of blood volume or a drop in blood pressure e. Renin is an enzyme that leads to a series of chemical reactions resulting in the production of angiotensin II , which in turn stimulate aldosterone release.

Aldosterone causes an increase in salt and water reabsorption into the bloodstream from the kidney thereby increasing the blood volume, restoring salt levels and blood pressure. The symptoms include high blood pressure, low blood levels of potassium and an abnormal increase in blood volume. Low aldosterone levels are found in a rare condition called Addison's disease.

In Addison's disease, there is a general loss of adrenal function resulting in low blood pressure, lethargy and an increase in potassium levels in the blood see the article on Addison's disease for further information. About Contact Events News.

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