Effects of tilting and volume loading on plasma levels and urinary excretion of relaxin, NT-pro-ANP, and NT-pro-BNP in male volunteers

Abstract

The polypeptide relaxin (RLX) has been suggested to play a role in cardiorenal integration and to be related to the natriuretic peptide system. We hence examined the effects of variations in thoracic blood volume and intravenous volume loading on plasma and urinary RLX levels and associated changes in natriuretic peptide levels in healthy men. Two groups of eight subjects were randomly tilted into a 15 degrees feet-down or a 15 degrees head-down position. Ten volunteers were crossover subjected to an infusion of 15 ml/kg of 0.9% NaCl (over 60 min) or control during an observation period of 10 h. Blood and urine were sampled at timed intervals. RLX, NH(2)-terminal prohormones of atrial natriuretic peptide (NT-pro-ANP), and NH(2)-terminal prohormones of brain natriuretic peptide (NT-pro-BNP) were determined by enzyme, radio-, and electrochemoluminescence immunoassays, respectively. NT-pro-ANP levels (in percentage of baseline levels) were higher (P < 0.05) during the head-down (124 +/- 13%) than during the feet-down position (82 +/- 6%). NT-pro-BNP and RLX were not affected by tilting. Volume loading induced a short-lasting increase in plasma NT-pro-ANP, a delayed increase in plasma NT-pro-BNP, had no effect on plasma RLX, and induced a parallel increase in urine flow, renal excretion of sodium, RLX, and NT-pro-BNP. It is concluded that variations in thoracic blood volume in healthy men are not associated with variations in plasma RLX. Increased urinary RLX and NT-pro-BNP excretion during volume loading suggest renal production and a possible role of kidney-derived RLX and brain natriuretic peptide in sodium homeostasis in men.

High Intraindividual Variation of B-Type Natriuretic Peptide (BNP) and Amino-Terminal proBNP in Patients with Stable Chronic Heart Failure

“…BNP (28 ), by Ͼ200% in a delayed fashion after a few hours (29 ). Water consumption during exercise in the heat, i.e., with dehydration, also increased BNP by Ͼ400% (27 ), but the effects of typical daily beverage consumption on BNP are unknown.…”

Characterization of NT-proBNP in Human Urine

“…Urine NT-proBNP immunoreactivity has been determined in physiological studies (9,10 ), in heart failure (11)(12)(13)(14), for screening of left ventricular dysfunction in the community (15 ), and for prediction of cardiovascular events in heart failure (16 ). These studies and an editorial (17 ) suggest that urine NT-proBNP represents an alternative to plasma NT-proBNP as a clinical biomarker.…”

The Alteration Of Plasma Atrial Natriuretic Peptide Levels Induced By Postural Changes In Archery Athletes

“…[31] Sağlıklı kişiler üzerinde yapılan bir çalışmada kişi-ler 15° eğimde baş aşağı ve ayrıca ayaklar aşağı gelecek şekilde tutulmuş, baş aşağı pozisyona bağlı plazma pro-ANP düzeylerinin artış gösterdiği saptanmıştır. [32] Vogelsang ve ark.nın [13] çalışmasında da oturur pozisyona göre yatar pozisyonda, plazma ANP düzey-lerinin daha yüksek olduğu belirtilmiştir. Ancak bu iki çalışmada, kişilerin sportif özelliklerine göre bir ayrım yapılmamıştır.…”