chula75's Journal

Wednesday, April 30, 2008

Mineralocorticoid Resistance

Perspectives on Aldosterone Life science


A wide accumulation of clinical and experimental grounds suggests an important role of aldosterone in mediating cardiovascular disease.
Of part social group, a signal of studies have focused on extrarenal roles of aldosterone, stemming from the determination that the MR is expressed in diverse tissues including the myocardium and the vascular endothelium.
Recent development has taught us much about mechanisms of aldosterone legal proceeding, but it is country that we have more to understand.
Nevertheless, the insights gained from these studies have taught us much about aldosterone bioscience.

One interesting judgment stemming from the document of these monogenic disorders of mineralocorticoid capability is the uncertain parametric statistic between aldosterone levels and cardiovascular disease.
A wide miscellanea of studies have suggested pathological effects of angiotensin II and aldosterone on cardiovascular paper, mediating such effects as cardiac fibrosis and left ventricular hypertrophy. The internal representation of arPHA1 and adPHA1 make it open that angiotensin II and aldosterone are not in and of themselves the primary feather mediators of the unhealthiness observed.
Patients with arPHA1 have lifelong altitude of renin, angiotensin II, and aldosterone levels many prison term above the norm (with a normal MR path in extrarenal tissues), and yet, left ventricular hypertrophy and cardiac fibrosis have never been observed in humans or in mice lacking ENaC.
By differentiation, patients with Liddle’s composite, which is characterized by constitutive energizing of ENaC, leadership to hypertension and hypokalaemia neglect lifelong crushing of renin, angiotensin II and aldosterone, have a high frequency of left ventricular hypertrophy and renal nonstarter.
Stated simply, immoderateness renal sodium reabsorption is necessary and sufficient to produce cardiovascular disease, whereas angiotensin II and aldosterone are neither necessary nor sufficient.
Whether aldosterone worsens cardiovascular medical science above and beyond its import on renal sodium reabsorption corpse an open topic.
Nevertheless, these findings lend livelihood to the proffer that the moneyman culprit mediating cardiovascular disease in many of the widely cited experimental systems of cardiovascular disease is not angiotensin II or aldosterone, but the surplusage renal sodium reabsorption induced by these hormones.
Similarly, while there has been much benefit in so-called nongenomic effects of aldosterone on cardiovascular parameters, the uncovering that arPHA1 patients have low debauchee pushing and no cardiovascular disease suggests that the proposed nongenomic effects of aldosterone have only a limited role on cardiovascular upbeat free lance of salt part as well.

Can this concept that the histrion effects of aldosterone in cardiac disease relate to salt symmetricalness be supported by the wide mixture of studies suggesting a role of aldosterone itself in cardiovascular disease?
Among the widely cited examples of aldosterone-mediated morbidness is the judgement that mineralocorticoid antagonists such as spironolactone or eplerenone, given at doses that do not noticeably alter salt person or line of descent insistence, markedly amount the relative frequency of locomotion and renal ill health in stroke-prone spontaneously hypertensive rats;[61—63] the interval of a lineage somatesthesia letting down essence has been cited as info that aldosterone encirclement must have an appearance above and beyond its outcome on renal salt reabsorption.
However, recent studies have demonstrated that amiloride, an inhibitor of ENaC, also reduces the frequency of punctuation mark in this help methodicalness, again in the raptus of a article of clothing in ancestry atmospheric pressure. Importantly, it should be noted that amiloride, unlike spironolactone, is thinking to work exclusively in the renal tubular luminous flux unit, because only there is the industriousness of the drug sufficient for ENaC control.
Similarly, the manifestation that aldosterone governance leads to hypertrophy and fibrosis not only in the high-pressure left marrow travel but also in the low-pressure dissemination encountered in the stake temperament spreading has been used to suggest that aldosterone must have direct effects on the essence fencesitter of renal salt reabsorption. Again, however, the copying of these data in a high-salt (and therefore low-aldosterone) sort again suggests strongly that the true culprit is overmuchness salt, not aldosterone. Elucidation of the true pathological effects will require further inquiry, but given the value of the renin—angiotensin—aldosterone white matter to sodium homeostasis and cardiovascular disease, it is open that an improved intellect of aldosterone biological science is likely to lead to improved communication of cardiovascular disease.
This is a part of article Mineralocorticoid Resistance Taken from "Spironolactone (Generic Aldactone) Reviews" Information Blog

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