Medullopressin: A New Pressor Activity from the Renal Medulla

Abstract

The kidney contains blood pressure-lowering substances, such as prostaglandin E2 or prostaglandin A2, and blood pressure-raising substances such as thromboxane A2. Most of the postulated substances, however,have not yet been isolated in a pure state and are of unknown structure. In the present study, we separated a chloroform extract from the medulla of pig kidneys using various chromatography procedures. Each fraction was tested in spontaneously hypertensive Wistar rats. One of these fractions caused a powerful blood pressure increase of 30.1 ± 7.1 mmHg systolic and 34.7 ± 6 mmHg diastolic (N =7; p =0.0003), reaching its maximum 55 ± 27 s after completion of the injection and lasting for 201 ± 59 s. A long-lasting contractile response in porcine and bovine coronary artery rings was observed. In the mouse aortic rings, the contractile response accounted for 0.38 ± 0.13 g, i.e., 31.9 ± 10.9% of the maximum potassium response (N =11; p =0.003). Because this activity could not be attributed to any known vasoactive substance, it was considered to arise from a novel underlying active substance in the kidney medulla, which we named medullo-

The vasodepressor function of the kidney: prostaglandin E2 is not the principal vasodepressor lipid of the renal medulla

“…These two proteins are rate‐limiting enzymes in the prostaglandin synthesis pathway, and renal medullary prostaglandins are believed to be potential regulators of sodium balance and blood pressure. However, as shown here for the first time, a kidney medulla extract like the one used in this study is devoid of prostaglandins, as well as of proteins, and thus free of any proteinaceous enzymes (Glodny & Pauli 2005). To our best knowledge, there is no other potential candidate molecule of known structure that has been isolated from or shown to be present in the renal medulla.…”

The Vasodepressor Function of the Kidney: Further Characterization of Medullipin and a Second Hormone Designated Angiolysin

“…This response was initially obscured, partly due to the presence of a hypertensive substance, which briefly triggered a rise in blood pressure. This blood pressureincreasing substance, however, can be separated from the blood pressure-lowering substance as previously described (10).…”