Objective To compare the characteristics of endogenous ouabain(EO) secretion with the other adrenocortical hormones and determine the effects of angiotensin Ⅰ (Ang Ⅰ ), and adrenocorticotrophin(ACTH) on the secretion of EO. Methods EO was measured by radioimmunoassay from primary cultured bovine adrenocotical cells (BAC). Results ①Ouabain was determined in the media of cultured BAC. Both EO and aldosterone secretion were decreased from the outer to inner layer of the cultured adrenal cortex, and the responses to Ang Ⅰ and ACTH were higher than that in the mid layer (P ＜0. 05) and inner layer (P ＜0. 01). Cortisol secretion was activated by Ang Ⅱ or ACTH was significantly higher in the mid layer and in the inner layer than that in the outer layer. ②The time-course experiment showed that the gradually rising amounts of aldosterone and cortisol could be determined dur ing the continuous incubation to 48h with or without Ang Ⅰ or ACTH. However, EO did not increase continuously af ter 24h of incubation in the basal secreting situation and after 12h of incubation in the stimulating situation by Ang Ⅱ or ACTH. ③There were obvious drops in aldosterone and cortisol secretion from 3rd day during a 21 day-period cell culture, but the peak secretion of ouabain was in 7th day. Conclusion It suggests that the secretory mechanism might be different between EO and aldosterone or cortisol. Also, Ang Ⅱ and ACTH might be involved in the regulation of EO secretion.

Objective To compare the effects of ouabain and digoxin on both the systolic blood pressure and sodium pump α-subunit isoforms gene expression in the aortic smooth muscle of rats. Methods Normal SpragueDawley rats were injected with ouabain (20μg·kg-1 ·d-1 ,i. p),digoxin (32 μg·kg-1 ·d-1,i. p)and normal saline once a day, respectively, and indirect systolic blood pressure was recorded once a week. Six weeks later,all the rats were killed and sodium pump α1-,α2-,and α3-subunit mRNA levels were detected in the aortic smooth muscle with reverse transcription polymerase chain reaction(RT-PCR) method. Results The systolic blood pressure of rats infused with ouabain increased significantly at the end of week 6 [132. 6± 9. 0 mmHg (1 mmHg ＝ 0. 133 kPa)vs 115. 7±8.2mmHg, P ＜0. 01] ,while no difference of blood pressure was found between digoxin group and NS group (P＞0.05).The expression of sodium pump α-subunit isoforms in aortic smooth muscle was regulated by either ouabain or digoxin:both ouabain and digoxin increased α1- and α3-subunit expression, α2-subunit decreased in digoxin group but unchanged in ouabain group. Conclusion These results suggest that both ouabain and digoxin could regulate sodium pump α-subunit isoform expression, which might be related to the physiological roles of endogenous ouabain and might be responsible for the difference between the pharmacological and toxicological effects of ouabain and digoxin,including their effects on blood pressure.

Objective To explore expression of endogenous ouabain(EO) in multiple adrenal tumors.Methods Thirty-one cases of adrenal tumors and 6 cases of healthy adrenal tissues were selected. The expression of EO in the adrenal tiss ue was detected with immunohistochemical streptavidin peroxadase conjugated(SP) method.Results Most of EO positive products were localized in cy toplasm of the zona reticularis of human adrenal cortex, and positive products s howed to be fine granular. There was no positive signal in the medulla. EO showe d on diffused positive in patients with pheochromocytoma accompanied high blood pressure[SBP:(165.22±7.61) mmHg, DBP:(105.52±4.26) mmHg], but there were neg ative in ones with normative blood pressure[SBP:(118.52±4.58) mmHg, DBP:(83±3.60) m mHg]. The expression of EO was positive in all adrenocortical hyperplasic, aden oma an d carcinoma, no matter its high or normative blood pressure. The degree of expre ssion of EO in adrenal tissues was related to the level of BP.Conclusion Expression of endogenous ouabain(EO) in health y adrenal tissue and adrenal tumors was a valuable morphological and pathophysio logical clue for the research on ouabain.