scholarly journals The propeptide Asn1–Tyr126 is the storage form of rat atrial natriuretic factor

1987 ◽  
Vol 241 (1) ◽  
pp. 265-272 ◽  
Author(s):  
G Thibault ◽  
R Garcia ◽  
J Gutkowska ◽  
J Bilodeau ◽  
C Lazure ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Atrial Natriuretic Factor ◽  
Secretory Granules ◽  
Activity Analysis ◽  
Differential Centrifugation ◽  
Percoll Gradient ◽  
Cell Debris ◽  
Glucuronidase Activity ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

Granules from rat atria were isolated by differential centrifugation and by a 53% (v/v) Percoll gradient after tissue homogenization in 0.25 M-sucrose/50 mM-Na2EDTA. About 40% of the immunoreactive ANF (atrial natriuretic factor) sedimented with the atrial granules during differential centrifugations. On the Percoll gradient, two distinct bands were observed. Cell debris, mitochondria, lysosomes, myofilaments and microsomes were mostly contained in the lightest-density (rho) (1.03-1.07 g/ml) fraction, as demonstrated by electron microscopy and by enzymic markers such as lactate dehydrogenase, monoamine oxidase, cytochrome c reductase, beta-glucuronidase and acid phosphatase. Atrial granules were mostly contained in the denser (rho 1.11-1.15 g/ml) band and were only slightly contaminated by lysosomes, as shown by beta-glucuronidase activity. Analysis of the ANF content in these isolated granules by h.p.l.c., amino acid composition and sequencing demonstrated that it was only the pro-ANF [ANF-(Asn1-Tyr126)-peptide]. The precursor was present in all granules, as demonstrated by immunocytochemistry. Since hormonal propeptides usually undergo intracellular processing, and the matured peptides are subsequently stored in the secretory granules, these results indicate that the processing pathway of ANF may be different from that of other hormonal peptides.

Regulated secretion of atrial natriuretic factor from cultured ventricular myocytes

1993 ◽  
Vol 264 (1) ◽  
pp. H282-H285 ◽  
Author(s):  
C. E. Irons ◽  
C. A. Sei ◽  
C. C. Glembotski
Keyword(s):  
Transit Time ◽  
Atrial Natriuretic Factor ◽  
Ventricular Myocytes ◽  
Secretory Granules ◽  
Subcellular Fractionation ◽  
Neonatal Rat ◽  
Cell Type ◽  
Regulated Secretion ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

We have investigated endothelin (ET)-regulated secretion of atrial natriuretic factor (ANF) from primary neonatal rat ventricular myocytes, where hormone release is thought to be constitutive. In a dose-dependent, nifedipine-sensitive manner, ET acutely enhanced ANF release by two- to fivefold over control cultures within 15 min of agonist exposure, demonstrating that ventricular myocytes display a primary characteristic of a regulated secretory cell type. Unlike atrial cultures, ET enhanced ANF release during the first 30 min of exposure; thereafter, secretion rates returned to control levels. KCl, however, effectively enhanced ANF release only during the first 15 min of exposure. Subcellular fractionation of ventricular culture homogenates did not reveal atrial-type dense secretory granules, and pulse-chase labeling experiments showed that the transit time of newly synthesized ANF was short in ventricular myocytes [time required for half of labeled ANF to be released from cells (t1/2) = 0.5-1.5 h) compared with atrial myocytes (t1/2 = 4 h). These results suggest that, whereas ventricular myocytes possess some of the characteristics of a constitutively secreting cell type (e.g., few, if any, dense secretory granules and rapid transit time for newly synthesized hormone); however, they also display the capacity for regulated secretion of ANF in response to the physiological agonist ET.

scholarly journals Contribution of blood and systemic circulation to the processing of pro-(atrial natriuretic factor)

1988 ◽  
Vol 250 (3) ◽  
pp. 665-670 ◽  
Author(s):  
K K Murthy ◽  
G Thibault ◽  
M Cantin
Keyword(s):  
Atrial Natriuretic Factor ◽  
Secretory Granules ◽  
Systemic Circulation ◽  
Initial Distribution ◽  
Metabolic Clearance ◽  
Time Intervals ◽  
Natriuretic Factor ◽  
Atrial Cardiocytes ◽  
Hydrolysis Of ◽  
Atrial Natriuretic

Atrial natriuretic factor-(Asn1-Tyr126)-peptide, the 13.6 kDa propeptide of atrial natriuretic factor (ANF), is stored in the secretory granules of atrial cardiocytes. ANF-(Ser99-Tyr126)-peptide, the 28-amino-acid species, is the circulating form of this hormone in the rat. As the site of maturation of the prohormone is still unknown, the present study was undertaken to understand the contribution of the circulation to the maturation process of pro-ANF. 125I-ANF-(Asn1-Tyr126)-peptide was incubated with whole rat blood, plasma or serum for different time intervals, and the products were analysed. There was minimal activation of the propeptide in either whole blood or plasma. Incubation with serum, however, resulted in the formation of an 11 kDa and a 3 kDa peptide which corresponded respectively to the N-terminal and C-terminal parts of the propeptide. These results suggest that hydrolysis of the propeptide in serum is brought about by enzymes that may be stimulated during coagulation but which may not play a major role in the activation of pro-ANF in the circulation. Plasma analysis at different time intervals after prohormone injection indicated a non-specific hydrolysis of the pro-ANF molecule. The disappearance rate curves, obtained with radiolabelled pro-ANF, suggested the presence of two components with half-lives of 2.1 +/- 0.4 min and 52.5 +/- 8.4 min respectively. A metabolic clearance rate of 1.49 +/- 0.22 ml/min and an initial distribution volume of 47.4 +/- 8 ml were calculated. These results indicate that the maturation of pro-ANF to its active circulating form takes place before it is released into the circulation.

Phosphorylation State of pro-Atrial Natriuretic Factor in Rat Atrial Secretory Granules*

Endocrinology ◽  
1990 ◽  
Vol 127 (6) ◽  
pp. 2839-2848 ◽  
Author(s):  
G. M. WILDEY ◽  
A. J. FISCHMAN ◽  
M. N. MARGOLIES ◽  
R. M. GRAHAM ◽  
C. J. HOMCY
Keyword(s):  
Atrial Natriuretic Factor ◽  
Secretory Granules ◽  
Phosphorylation State ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

scholarly journals Atrial natriuretic factor in the vena cava and sinus node.

1990 ◽  
Vol 38 (8) ◽  
pp. 1123-1135 ◽  
Author(s):  
C Sola ◽  
G Thibault ◽  
H Haile-Meskel ◽  
M B Anand-Srivastava ◽  
R Garcia ◽  
...  
Keyword(s):  
Superior Vena Cava ◽  
Atrial Natriuretic Factor ◽  
Secretory Granules ◽  
Superior Vena ◽  
Sinus Node ◽  
Vena Cava ◽  
Natriuretic Factor ◽  
Atrial Cardiocytes ◽  
Transitional Cells ◽  
Atrial Natriuretic

We investigated the localization of atrial natriuretic factor (ANF) mRNA and of immunoreactive ANF in the vena cava and sinus node of rat and, for comparative purposes, in atria and ventricles. In situ hybridization with an ANF cRNA probe revealed that the supradiaphragmatic portion of the inferior vena cava contains almost as much mRNA as the atria, whereas the levels were less in the superior vena cava and higher than in ventricles in the sinus node. Immunoreactive ANF (high Mr form) was found to be 22 times less abundant in the supradiaphragmatic vena cava and 148 times less abundant in the superior vena cava than in atrial cardiocytes. The wall of the supradiaphragmatic portion of the vena cava and the valve (eustachian valve) that separates the atrial cavity from that of the vein are made up of atrial-like cardiocytes containing secretory granules. The subendothelial area of the superior vena cava also contains atrial-like cardiocytes with secretory granules, whereas the outer portion of the vein is made up of "transitional cells" without or with only a few secretory granules. Secretory granules in the vena cava and nodal cells, as well as transitional cells, contain immunoreactive ANF. With immunocryoultramicrotomy, virtually all cells, whether atrial-like, transitional, or nodal, and even those without secretory granules, were found to contain immunoreactive ANF in their Golgi complex and in secretory vesicles in the vena cava and in the sinus node.

Binding and aggregation of pro-atrial natriuretic factor by calcium

1992 ◽  
Vol 262 (4) ◽  
pp. C907-C915 ◽  
Author(s):  
G. Thibault ◽  
A. F. Doubell
Keyword(s):  
Atrial Natriuretic Factor ◽  
Divalent Cations ◽  
Secretory Granules ◽  
Sodium Dodecyl ◽  
Carboxyl Groups ◽  
Condensed State ◽  
Natriuretic Factor ◽  
Ph Dependent ◽  
High Level ◽  
Atrial Natriuretic

Analysis of atrial secretory granule content by sodium dodecyl sulfate-gel electrophoresis followed by a 45Ca2+ overlay assay indicates that a 17,000 protein binds 45Ca2+. This protein, which can be immunostained by atrial natriuretic factor (ANF) antiserum, corresponds to proANF. Ca2+ binding is proportional to the amount of proANF and pH dependent. Generation of ANF-(1-98) by thrombin digestion of proANF does not affect Ca2+ binding. Blocking the carboxyl groups of proANF and the use of NH2-terminal fragments bearing those carboxyl groups demonstrated that the Ca(2+)-interaction site is probably located within the highly acidic portion (11-30) of the propeptide. Ca2+ binding to proANF induces its aggregation that can be verified by sedimentation. ProANF aggregation is Ca2+ dependent, being optimal at 10 mM, partially pH dependent, and greatly increased by high concentrations of proANF. However, because of its relatively low-binding affinity, Ca2+ can be substituted by other divalent cations such as Sr2+, Ba2+, or Mg2+. The high level of Ca2+ in atrial secretory granules and the aggregation of proANF in the presence of Ca2+ suggest a possible involvement of these physicochemical properties in the condensed state of the matrix of secretory granules. Indeed, detergent solubilization of the membrane of the secretory granules in presence of Ca2+ resulted only in a partial dissolution of the dense core matrix. We therefore postulate that, in the Golgi complex, proANF and Ca2+ associate to form a condensed aggregate that helps package secretory material into secretory vesicles.

Atrial Natriuretic Factor Receptors

1987 ◽  
Vol 16 (1) ◽  
pp. 63-77 ◽  
Author(s):  
John W. Jacobs ◽  
George P. Vlasuk ◽  
Michael Rosenblatt
Keyword(s):  
Atrial Natriuretic Factor ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

Acute and chronic sodium loading stimulates atrial natriuretic factor (ANF) in man

1986 ◽  
Vol 113 (1_Suppl) ◽  
pp. S165-S166 ◽  
Author(s):  
G. WAMBACH ◽  
S. GÖTZ ◽  
G. SUCKAU ◽  
G. BÖNNER ◽  
W. KAUFMANN
Keyword(s):  
Atrial Natriuretic Factor ◽  
Natriuretic Factor ◽  
Sodium Loading ◽  
Atrial Natriuretic
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