David L. Vesely

Three peptides from the atrial natriuretic factor prohormone amino terminus lower blood pressure and produce diuresis, natriuresis, and/or kaliuresis in humans.

BackgroundThree peptides consisting of amino acids 1-30, 31-67, and 79-98 of the 126–amino acid atrial natriuretic factor prohormone (proANF), which have blood pressure-lowering, diuretic, natriuretic, and/or kaliuretic properties in animals, were investigated to determine if they have similar properties in humans. Methods and ResultsThirty-six healthy, normotensive human volunteers (18 men and 18 women, ages 20 to 58 years) were divided into six similar groups based on age, sex, weight, blood pressure, and heart rate. After a 60-minute baseline period, 100 ng of proANFs 1-30, 31-67, 79-98, or ANF/kg body wt per minute was given intravenously for 60 minutes followed by a 3-hour postinfusion data collection period. Each of the atrial natriuretic peptides decreased systolic and diastolic blood pressures (P<.05), with proANF 31-67 causing the largest decrease. Urine flow increased 4- to 12-fold and was still significantly increased (P<.01) for 2 to 3 hours after stopping the respective infusions of proANFs 1-30, 31-67, and 79-98. Atrial natriuretic factor (ANF) increased urine flow 4- to 11-fold but by 2 hours after infusion was significantly increased in only 1 of 6 subjects. Sodium excretion increased 3-to 8-fold, 3- to 6-fold, 0- to 2-fold (NS), and 3- to 11-fold, respectively, with proANFs 1-30, 31-67, 79-98, and ANF. Natriuretic effects of proANFs 1-30 and 31-67 were significantly prolonged (P<.001) compared with ANF. ProANFs 1-30, 31-67, 79-98, and ANF increased potassium excretion 2- to 3-fold, 0-fold, 3- to 4-fold, and 2-fold, respectively. High-performance gel permeation chromatography followed by the respective radioimmunoassays revealed that proANFs 1-30, 31-67, 79-98, and 68-98, as well as ANF circulate as distinct peptides. ConclusionsProANFs 1-30, 31-67, and 79-98, as well as ANF have significant blood pressure-lowering and diuretic properties. ProANFs 1-30 and 31-67 also have natriuretic properties in humans that are significantly (P<.001) prolonged compared with ANF. ProANF 79-98, although not possessing any natriuretic property, is the strongest stimulator of potassium excretion of the four atrial natriuretic peptides.

The N-terminus and a 4,000-MW peptide from the midportion of the N-terminus of the atrial natriuretic factor prohormone each circulate in humans and increase in congestive heart failure.

Two peptides consisting of amino acids 1-30 and 31-67 of the N-terminus of the prohormone of atrial natriuretic factor (pro-ANF) that have vasodilatory and natriuretic properties were investigated to determine if they circulate in humans. Specific and sensitive radioimmunoassays were developed to amino acids 1-30, 31-67, and 99-126 of pro-ANF. Evaluation of human plasma that had been subjected to reverse-phase high-pressure liquid chromatography suggested that pro-ANFs 1-30 and 31-67 as well as ANF were distinct peaks in human plasma corresponding exactly to pure synthetic peaks of these peptides on high-pressure liquid chromatography. Molecular weight determination of the endogenous immunoreactive peptides measured in plasma by G-50 Sephadex gel permeation chromatography revealed that the pro-ANF 1-30 radioimmunoassay recognized a peptide of 10,000 MW, which is consistent with it measuring the whole N-terminus of pro-ANF (amino acids 1-98) but without ANF (C-terminus) attached to it. The pro-ANF 31-67 radioimmunoassay recognized mainly (more than 95%) a peptide of 3,900-4,000 MW, which corresponds closely with its actual molecular weight of 3,878. Our ANF radioimmunoassay recognizes a peptide in plasma of 3,000 MW with the known molecular weight of ANF being 3,081. The mean circulating concentrations of immunoreactive pro-ANF 1-98, pro-ANF 31-67, and ANF in 54 control subjects were 531 +/- 25, 371 +/- 18, and 22 +/- 1 fmol/ml (+/- SEM), respectively. Thirty patients with varying severity of congestive heart failure were also studied. The N-terminus, C-terminus, and pro-ANF 31-67 increased: twofold for New York Heart Association functional Class II, threefold to ninefold for Class III, and 10- to 20-fold for Class IV patients with congestive heart failure. Thus, the N-terminus and a 4,000-MW peptide from the midportion of the N-terminus of pro-ANF as well as ANF circulate normally and increased proportionately to the increasing severity of congestive heart failure. However, because the pro-ANF 31-67 radioimmunoassay was the only assay that discriminated between patients with Class I congestive heart failure and control subjects, this assay may be the most useful to accurately classify the severity of congestive heart failure.

Adrenomedullin, endothelin, neuropeptide Y, atrial, brain, and C-natriuretic prohormone peptides compared as early heart failure indicators

OBJECTIVES The present investigation was designed to determine the best endogenous plasma marker of early congestive heart failure (CHF). METHODS Forty volunteers with mild CHF (New York Heart Association Class I, n = 12), moderate (Class II, n = 8), or severe (Class III and Class IV, each = n of 5) and 10 age-matched healthy individuals had the simultaneous evaluation of their respective plasma samples by the following radioimmunoassays: atrial natriuretic peptide, ANP; three N-terminal ANP prohormone assays, i.e., proANPs 1-30, 31-67, and 79-98 with the numbers referring to their amino acid (a.a.) sequences in their 126 a.a. prohormone; brain (BNP) and C-natriuretic peptides; N-terminal BNP prohormone; adrenomedullin; neuropeptide Y and endothelin. RESULTS ProANPs 31-67, 1-30 and 79-98 had 100% (P = 0.01), 83% (P = 0.09) and 50% (P = 0.74) sensitivity in differentiating Class I CHF subjects from healthy subjects. The ANP, BNP, NT-proBNP, CNP, adrenomedullin, neuropeptide Y, and endothelin assays could not differentiate mild CHF subjects from healthy individuals. Logistic regression analysis revealed that only proANP 31-67 significantly (P = 0.0001) discriminated between early CHF (5226 +/- 377 pg/ml) and healthy individuals (1595 +/- 157 pg/ml). The positive and negative predicative values of proANP 31-67 were excellent (100% for each). The peptides measured in these assays were found to be independent markers of CHF with respect to left ventricular ejection fraction. CONCLUSIONS ProANPs 31-67 is the most sensitive marker in discriminating NYHA Class I CHF subjects from healthy individuals. The ANP, BNP, NT-proBNP, CNP, adrenomedullin, neuropeptide Y and endothelin radioimmunoassays cannot discern mild CHF. These peptides are independent of left ventricular ejection fraction.

Atrial natriuretic prohormone peptides 1–30, 31–67, and 79–98 vasodilate the aorta

Human prohormone atrial natriuretic peptides 1-30, 31-67, and 79-98 caused vasodilation of porcine aortas which began in 30 seconds and was maximal at 10 minutes. These three peptides were found to be equally potent to atrial natriuretic factor in their vasodilatory activity which was found with or without endothelium present. This vasodilation was associated with a 4 to 5 fold increase in cyclic GMP in the aorta secondary to activation of particulate guanylate cyclase [E.C. 4.6.12]. These data demonstrate that three N-terminal peptide segments of the atrial natriuretic factor prohormone cause vasodilation.

Two new hormones: Prohormone atrial natriuretic peptides 1–30 and 31–67 circulate in man

Two peptides consisting of amino acids 1-30 and 31-67 of the N-terminal end of the prohormone of atrial natriuretic factor (pro ANF) which vasodilate aortas in vitro, lower blood pressure in vivo, and have natriuretic properties were found to circulate in 54 normal human volunteers. The mean circulating concentration of pro ANF 1-30 was 1861 +/- 87 pg/ml (SEM) while pro ANF 31-67 mean concentration was 1478 +/- 71 pg/ml versus a level of 67 +/- 3 pg/ml for atrial natriuretic factor (ANF). In chronic renal failure their mean concentrations increased to 40,484 +/- 6,929 pg/ml (SEM), 108,566 +/- 16,888 pg/ml, and 348 +/- 81 pg/ml for pro ANFs 1-30 and 31-67 and ANF respectively. Since pro ANF 1-30 and pro ANF 31-67 circulate in man and have physiologic effects they meet the criteria of two new hormones.

Increased Release of the N-Terminal and C-Terminal Portions of the Prohormone of Atrial Natriuretic Factor During Immersion-Induced Central Hypervolemia in Normal Humans

Abstract The role of peptides from the N terminus and C terminus of the 126 amino acid atrial natriuretic factor (ANF) prohormone in modulating renal sodium and water handling has not been defined. Since water immersion to the neck (Nl) provides an acute central volume expansion identical to that produced by 2 liters of saline but without plasma compositional change, immersion to the neck was used to assess the N-terminal and C-terminal portions of the ANF prohormone response to acute central blood volume expansion in seven seated sodium-replete normal subjects. Both the C terminus, which contains amino acids 99– 126 and is identical to ANF, and the whole N terminus (i.e., amino acids 1–98) increased promptly with Nl and peaked after 1 hr of immersion. A M, 3900 peptide from the midportion of the N terminus consistent with amino acids 31–67 (i.e., pro-ANF-31–67) also increased with Nl and followed a pattern of increasing circulating concentration nearly identical to that of the whole N terminus of the prohormone, except that its maximal concentration was at the second hour of the 3 hr of Nl. With cessation of immersion, ANF decreased to preimmersion levels within 1 hr whereas the N terminus and pro-ANF-31–67, although their circulating concentrations were decreasing, were still significantly elevated at 1 hr. These findings suggest that the increase in plasma ANF, the N terminus of the ANF prohormone, and pro-ANF-31–67 from the midportion of the N terminus, with natriuretic properties similar to ANF, contribute to the natriuretic response to Nl, implying a physiologic role for these atrial peptides in modulating volume homeostasis in humans.

Atrial Natriuretic Peptide Prohormone Gene Expression: Hormones and Diseases That Upregulate its Expression

Atrial natriuretic peptides consist of a family of peptide hormones that are synthesized by three separate genes and then stored as three different prohormones (i.e., 126‐amino acid [a.a.]) atrial natriuretic peptide (ANP), 108‐a.a. brain natriuretic peptide (BNP), and 126‐a.a. C‐natriuretic peptide (CNP) prohormones. The gene encoding for the synthesis of the atrial natriuretic peptide prohormone (proANP) consists of three exons and two introns. Exon 1 encodes the signal peptide and the first 16 a.a. of the ANP prohormone. These 16 a.a. form the N ‐terminus of a peptide hormone named long‐acting natriuretic hormone (LANH). A valine‐to‐methionine substitution in LANH results in a 2‐fold increased incidence of strokes in humans. Exon 2 of the proANP gene encodes for three peptide hormones, i.e., vessel dilator, kaliuretic hormone, and ANP. Each of the proANP gene products have vasodilatory, diuretic, natriuretic, and/or kaliuretic properties. Stretch, glucocorticoids, thyroid hormone(s), mineralocorticoids, and calcium enhance proANP gene expression. Enhanced proANP gene expression is found in congestive heart failure, hypertension, and cirrhosis with ascites. The proANP gene is present with invertebrates and plants as well as in humans and other vertebrates.

Circadian rhythm of prohormone atrial natriuretic peptides 1-30, 31-67 and 99-126 in man.

Two peptides consisting of amino acids 1-30 and 31-67 of the N-terminal end of the prohormone of the atrial natriuretic factor (pro ANF), vasodilate aortas in vitro, lower blood pressure in vivo, and have natriuretic properties similar to the atrial natriuretic factor (ANF, amino acids 99-126 of the prohormone). It has been recently discovered that pro ANF 1-30 and pro ANF 31-67 as well as ANF circulate in man. To determine if these three peptide hormones have a circadian variation in their circulating plasma concentrations, eight housestaff volunteers were studied on a day when they were in the hospital for 24 hr. These 5 men and 3 women, ages 25 to 39 had blood samples taken at 0800, 1200, 1600, 2000, 0000, 0400 and 0800 on the following day. One-half of these house officers were up all night while the other half went to sleep from midnight to 0800 and had their 0400 plasma samples drawn while in a supine position. The peak level for all three peptide hormones was at 0400 for both supine and upright subjects. It was concluded that there are circadian rhythms in normal, active people of these three peptide hormones, whose peak levels are at 0400 irrespective of posture.

Expression of brain natriuretic peptide by human bone marrow stromal cells

Bone marrow stromal cells (BMSC) have been shown to generate neural cells under experimental conditions in vitro and following transplantation into animal models of stroke and traumatic CNS injury. Hastened recovery from the neurological deficit has not correlated with structural repair of the lesion in the stroke model. Secretory functions of BMSC, such as the elaboration of growth factors and cytokines, have been hypothesized to play a role in the enhanced recovery of neurological function. Using gene expression arrays, real time RT-PCR and radioimmunoassay, we have found that brain natriuretic peptide (BNP) is synthesized and released by BMSC at physiologically relevant levels in vitro. BNP, like its close homolog atrial natriuretic peptide (ANP), exerts powerful natriuretic, diuretic and vasodilatory effects. We speculate that transplanted BMSCs facilitate recovery from brain and spinal cord lesions by releasing BNP and other vasoactive factors that reduce edema, decrease intracranial pressure and improve cerebral perfusion.

Atrial natriuretic peptides in pathophysiological diseases

Time for primary review 32 days. Atrial natriuretic peptides (ANPs) consist of a family of peptides which are synthesized and then stored as three different prohormones (i.e., 126 amino acid [a.a.] atrial natriuretic peptide (ANP), 108 a.a. brain natriuretic peptide (BNP), and 126 a.a. C-natriuretic peptide prohormones (CNP) prohormones) [1]. The present review will concentrate on atrial peptides and especially on the natriuretic peptides originating from the ANP prohormone in pathophysiological conditions. There are several excellent recent reviews on the biochemistry and molecular biology of the natriuretic peptides [2,3] and their physiology [4–6] so these aspects will not be reviewed in detail in the present review. ### 2.1 Cerebrovascular disease — molecular biology of natriuretic peptides To understand which of the atrial natriuretic peptides may be associated with cerebrovascular accidents (i.e., strokes) [7,8] and other cardiovascular disease states, it is necessary to briefly review the molecular biology of how the respective atrial natriuretic peptides are synthesized. The gene encoding for the synthesis of atrial natriuretic peptide preprohormone consists of three exons (coding) sequences separated by two intron (intervening) sequences (Fig. 1) [9–12]. Exon 1 encodes the signal peptide which is cleaved from the preprohormone (152 a.a.) in the endoplasmic reticulum to form a prohormone of 126 a.a., which is the storage form of the various atrial peptide hormones within tissues [11–13]. Exon 1 also encodes for the first 16 amino acids of this prohormone [9–12] which after proteolytic processing of the ANP prohormone is also the first 16 a.a. of a peptide hormone named long acting natriuretic peptide (LANP) (Fig. 1). Exon 3 encodes for the terminal tyrosine (i.e., a.a. 126 of the ANP prohormone) in humans and 3 a.a. (Try-Arg-Arg) in rat, mouse, rabbit, and cow [9–13]. Exon 2 encodes for the rest of the prohormone (i.e., a.a. 17–125 in humans) [9–13]. Fig. 1 Structure of … * Tel.: +1-813-972-7624; fax: +1-813-972-7623 vesely.david_l{at}tampa.va.gov