on July 20, 2009
Published online before print July 20, 2009, doi: 10.1161/HYPERTENSIONAHA.109.135608
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Submitted on May 2, 2009
From the Christchurch Cardioendocrine Research Group (T.C.R.P., E.A.E., T.G.Y., S.C.P., A.M.R.), Department of Medicine, University of Otago Christchurch, Christchurch, New Zealand. * To whom correspondence should be addressed. E-mail: suetoniapalmer{at}clear.net.nz.
Abstract—Production and clearance of plasma C-type natriuretic peptide (CNP) and amino terminal (NT)-proCNP immunoreactivity in the human circulation remain poorly characterized. Accordingly, we have measured arterial and venous concentrations of CNP and NT-proCNP across multiple tissue beds during cardiac catheterization in 120 subjects (age: 64.2±9.0 years; 73% men) investigated for cardiovascular disorders. The heart, head and neck, and musculoskeletal tissues made the clearest contributions to both plasma CNP and NT-proCNP (P<0.05). Net release of NT-proCNP was also observed from hepatic tissue (P<0.001). Negative arteriovenous gradients for CNP were observed across renal, hepatic, and pulmonary tissue (P<0.05), indicating net clearance, whereas no tissue-specific site of NT-proCNP clearance was identified. Age, mean pulmonary artery pressure, left ventricular end diastolic pressure, Brandt score of myocardial jeopardy, and troponin I were independent predictors of circulating CNP levels in multivariable analysis. Sex and kidney function were independently predictive of arterial NT-proCNP. The proportional step-up of CNP (+60%) across the heart was less than for brain natriuretic peptide (+123%) but greater than for NT-pro-brain natriuretic peptide (NT-proBNP) (+36%) and NT-proCNP (+42%; P<0.001 for all). We conclude that cardiac and head and neck tissue are important sources of CNP. Circulating CNP but not NT-proCNP concentrations are related to cardiac hemodynamic load and ischemic burden. Although cardiac release is most evident, multiple additional tissues release NT-proCNP immunoreactivity without evidence for an organ-specific site for NT-proCNP degradation. Taken together, differences in magnitude and direction of transorgan gradients for CNP compared with NT-proCNP suggest net generalized cosecretion with differing mechanisms of clearance.
Revised on May 24, 2009
Regional Release and Clearance of C-Type Natriuretic Peptides in the Human Circulation and Relation to Cardiac Function
Suetonia C. Palmer*;
Key words: natriuretic peptides • circulation • plasma • glomerular filtration rate • human