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Báo cáo Y học: Endogenous cardiac glycosides, a new class of steroid hormones

The search for endogenousdigitalishas led to the isolationof ouabain as well as several additional cardiotonic steroids of the cardenolide and bufadienolide type from blood, adre-nals, and hypothalamus.The concentration of endogenous ouabain is elevated in blood upon increased Na + uptake, hypoxia, and physical exercise.Changes in blood levels of ouabain upon physical exercise occur rapidly. | Eur. J. Biochem. 269 2440-2448 2002 FEBS 2002 doi 10.1046 j.1432-1033.2002.02911.x MINIREVIEW Endogenous cardiac glycosides a new class of steroid hormones Wilhelm Schoner Institut fur Biochemie und Endokrinologie Justus-Liebig-Universitdt Giessen Germany The search for endogenous digitalis has led to the isolation of ouabain as well as several additional cardiotonic steroids of the cardenolide and bufadienolide type from blood adrenals and hypothalamus. Tie concentration of endogenous ouabain is elevated in blood upon increased Na uptake hypoxia and physical exercise. Changes in boood levels oT ouabain upon physical exercise occur rapidly. Adrenal cortical cells in tissue culture release ouabain upon addition of angiotensin II and epinephrine and it is thought that ouabain is released from adrenal cortex in vivo. Ouabain ỊeveỊs in blood are elevated in 50 of Caucasians with low-renin hypertension.Infusion over several weeks of low concentrations of ouabain but not of digoxin induces hypertension in rats. A digoxmliike compound which has been Íolhie cl from human urine and adrenals as well various other endogenous cardiac glycosides may counterbalance their actions within a regulatory framework of water and salt metabolism. MannoUlr arnnin. for ínslnnee. wHoe cnn-centration is increased after cardiac infarction may show natriuretic properties because it inhibits the a1 isofotm of Na K -ATPase the main sodium pump isoform of the kidney much better than other sodium pump isoforms. n analogy to other steroid hormones cardiotonic steroid hormones in blood are bound to a specific cardiac glycoside binding globulin. The ci íscovery of ouabain as a new adrenal hormone affecting Na metabolism and the development of the new ouabain antagonist PST 2238 allows for new possibilities for the therapy of hypertension and congestive heart failure. This will ead n turn oo a betrer understanding of ithe disease on a physiological and endocrinological level and of the action of .