DERIVATION OF ANTIHYPERTENSIVE NEUTRAL RENOMEDULLARY LIPID FROM RENAL VENOUS EFFLUENT

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  • 1 January 1982
    • journal article
    • research article
    • Vol. 99  (1) , 64-75
Abstract
The ANRL [antihypertensive neutral renomedullary lipid] was derived from the renal venous effluent as the kidney exerted its nonexcretory antihypertensive function. This was made possible by 3 developments: improvement in the extraction of ANRL from fresh renal medulla; the fact that purified ANRL caused an acute vasodepressor effect (acted as a vasodilator); and experience with unclipping the 1-kidney, 1 clip hypertensive rat. Unclipping after an anastomosis between the ureter and the vena cava caused the MAP [mean arterial pressure] to return to normal levels in an average of 20 h. At an average of 5 h, when the MAP had dropped an average of 34 mm Hg (from .apprx. 190), an exchange infusion was started and blood was collected from the renal vein. The plasma was separated, lyophilized and extracted for total lipids. The lipids were subjected to 2 TLC procedures and tested for vasodepressor activity. Renal venous effluent, under those conditions, yielded a considerable amount of vasodepressor lipid that was similar to that derived from fresh renal medulla. Controls (normal, nephrectomized and hypertensive animals) yielded little or no such lipid. Indomethacin did not interfere with the derivation of the vasodepressor lipid. As the MAP was lowered and the ANRL-like lipid appeared in the renal venous blood, the RIC [renomedullary interstitial cell] degranulated. The RIC appear to be the source of the antihypertensive lipid. This lipid may well be the sought-after antihypertensive hormone.