Reversal of hypertension by transplants and lipid extracts of cultured renomedullary interstitial cells.

Transplants and lipid extracts of the same monolayer tissue culture of renomedullary interstitial cells from murine renal medulla exerted a similar antihypertensive action in rats having hypertension of the sodium-volume-dependent-type. The antihypertensive action resembled that caused by lipid extracts of rabbit renal medulla and extracts of lapine renomedullary interstitial cells grown in tissue culture. The recession of the arterial pressure of the hypertensive animals usually occurred slowly and steadily to a maximum within 6 to 12 hours. On occasions, a substantial acute depressor effect preceded the slow and steady decline of the pressure. As the pressure was lowered, there was either minimal or no change in the pulse rate. The lowering of the hypertensive pressure before there was vascularization of the transplant appears to support the view that the transplanted cells secreted and/or liberated an antihypertensive substance(s) that seeped out and was absorbed by nearby capillaries and/or lymphatics and circulated and acted in the manner of a hormone. The extracted and purified lipid from the same cells as used for transplantation is proposed as a candidate for such hormonal action. Evidence is presented that minimizes the possibility of the classic renomedullary prostaglandins as this antihypertensive lipid. The findings add support to the concept that the kidney exerts a hormonal antihypertensive action that opposes the well known hormonal prohypertensive renal actions.