Synthesis and biological activity of a linear fragment of the atrial natriuretic factor (ANF).

A linear fragment of the atrial natriuretic factor, ANF(106-125), unable to form an intramolecular cystine bridge, was synthesized by the solid-phase method. The fragment showed smooth muscle relaxant activity in the rabbit aorta and chick rectum assays, an inhibitory effect on aldosterone secretion from bovine adrenal zona glomerulosa cells, and had affinity for specific ANF receptors located in zona glomerulosa cell membranes. The potency of ANF(106-125) in these four assay systems was about two to three orders of magnitude lower than that of ANF(103-125) which contains the intact cyclic structure.

Immunoreactivity of vasopressin and a novel pituitary protein '7B2' in Long-Evans and Brattleboro rat hypothalamus and hypophysis.

The unlabeled antibody (peroxidase-anti-peroxidase) method was used to simultaneously localize vasopressin and a novel pituitary protein designated '7B2' in rat hypothalamus and pituitary. Results showed the common localization of both substances within magnocellular neurons of supraoptic, supraoptic retrochiasmic and paraventricular nuclei. The distribution was also similar in the inner zone of the median eminence and in the posterior lobe of the pituitary gland.

Gluco- and mineralocorticoids may regulate the natriuretic effect and the synthesis and release of atrial natriuretic factor by the rat atria in vivo.

Adrenalectomy abolished the acute natriuretic effect of ANF which was partially restored to about 50% by combined therapy with gluco- and mineralocorticoids. It is suggested that the lack of effect of ANF may be due to a decreased renal vascular reactivity to the peptide in adrenalectomized animals. Simultaneous administration of Dexamethasone and Deoxycorticosterone acetate to adrenalectomized rats produced a marked increase in immunoreactive ANF in atrial tissue and plasma.

Reduction of blood pressure and increased diuresis and natriuresis during chronic infusion of atrial natriuretic factor (ANF Arg 101-Tyr 126) in conscious one-kidney, one-clip hypertensive rats.

Conscious one-kidney, one-clip hypertensive rats and their normotensive controls were infused during 7 days with synthetic ANF (Arg 101-Tyr 126) at 100 ng/hr/rat (35 pmol/hr/rat) by means of osmotic minipumps. The basal blood pressure of 193 +/- 6 mmHg gradually declined to 145 +/- 6 mmHg at day 4 after the infusion was started. No changes in blood pressure were observed in ANF-infused normotensive rats.

Identification of a biologically active circulating form of rat atrial natriuretic factor.

An atrial natriuretic peptide has been isolated from plasma of morphine treated rats by means of glass beads extraction, immunoaffinity chromatography, and reverse phase HPLC. 1.3 micrograms of immunoreactive material was obtained.

ANF (Arg 101--Tyr 126) is the peptide secreted by rat atrial cardiocytes in culture.

The atrial natriuretic factor (ANF) secreted from rat cardiocytes in culture was purified and characterized. The purification procedure involves extraction of ANF by activated Vycor glass, followed by HPLC on C18 mu Bondapak and Vydac columns. The detection of ANF in column eluates was performed by a simple and sensitive radioimmunoassay.

Adenosine-sensitive adenylate cyclase in rat anterior pituitary.

An adenosine-sensitive adenylate cyclase has been demonstrated in anterior pituitary cultured cells in the present studies. N-ethylcarboxamideadenosine (NECA), L-N6-phenylisopropyladenosine (PIA), and 5'-N-methylcarboxamideadenosine (MECA), all stimulated adenylate cyclase in a concentration-dependent manner in the order of potency NECA greater than PIA greater than MECA. Adenosine showed a biphasic effect on adenylate cyclase: stimulation at lower and inhibition at higher concentrations, whereas 2'-deoxyadenosine only inhibited adenylate cyclase in a concentration-dependent manner.

Chronic infusion of low doses of atrial natriuretic factor (ANF Arg 101-Tyr 126) reduces blood pressure in conscious SHR without apparent changes in sodium excretion.

Conscious SHR and WKY rats were infused during 7 days with synthetic ANF (Arg 101-Tyr 126), 100 ng/hr/rat (35 pmol/hr/rat) by means of miniosmotic pumps. The SHR initial blood pressure of 177 +/- 5 mmHg gradually dropped to 133 +/- 3 and 142 +/- 4 mmHg the last two days of infusion. No significant change in blood pressure was observed in the ANF-infused WKY group.

Effect of different anesthetics on immunoreactive atrial natriuretic factor concentrations in rat plasma.

The effect of different conditions of blood withdrawal and use of different anesthetics on immunoreactive atrial natriuretic factor (IR-ANF) concentrations in plasma was studied in rats. The concentration of IR-ANF in plasma from jugular vein of non-anesthetized conscious rats, cannulated either 24 hr before blood withdrawal was 93.9 +/- 17.

Identification of aldosterone secretion inhibitory factor in bovine adrenal medulla.

We report the first demonstration of an Aldosterone Secretion Inhibitory Factor (ASIF) in acid extracts of bovine adrenal medulla. Following separation from catecholamines and enkephalins, this factor leads to an 80% inhibition of PGE1-stimulated secretion of aldosterone from bovine adrenal zona glomerulosa. ASIF is retained on cation exchange gels and behaves as a small 5K-dalton peptide on Sephadex G-50.

Localization of immunoreactive synthetic atrial natriuretic factor (ANF) in the heart of various animal species.

The localization of two synthetic fragments of the C-terminal portion of atrial natriuretic factor: Arg 101-Tyr 126 which displays full biological activity and Leu 94-Arg 109 which is completely devoid of biological activity, has been investigated by immunohisto- and immunocytochemical methods in the heart of mammals (rat, mouse, guinea pig, hamster, rabbit, cat, dog, man) and nonmammalian vertebrates toad (Bufo marinus), frog (Rana catesbeiana), fish (Cyprinus carpio, Puntius schwanenfeldi, Cichlosoma biocellatum, Carrasius auratus), snake (Python reticulatus) and hen. Antibodies against the synthetic fragments of ANF were raised in rabbits and used either for immunofluorescence (Coons' technique), immunohistochemistry (unlabeled antibody technique) or immunocytochemistry (protein A-gold technique). Results obtained by immunofluorescence and by the unlabeled antibody technique were similar: antibodies against Arg 101-Tyr 126 ANF allowed visualization of granulated cardiocytes in the atria of all mammals.

Vascular and adrenal receptors for atrial natriuretic factor in the rat.

Previous studies have shown that atrial natriuretic factor, a powerful vasorelaxant of precontracted vessels, inhibits the secretion of aldosterone stimulated by angiotensin II, adrenocorticotropic hormone, and potassium. We now report the presence of specific binding sites for atrial natriuretic factor in rat blood vessels (mesenteric and renal arteries) and adrenal capsules. Radioiodinated synthetic atrial natriuretic factor bound to a single class of high-affinity (KD = 0.

Ninhibin: a sperm factor attenuates the atrial natriuretic factor mediated inhibition of adenylate cyclase: possible involvement of inhibitory guanine nucleotide regulatory protein.

The effect of ninhibin, a sperm factor extracted from bovine sperm, was studied on adenylate cyclase from rat aorta. Ninhibin treatment of the membranes activated adenylate cyclase in a concentration dependent manner. The maximal activation (approximately equal to 4-fold) was obtained at 2micrograms ninhibin and at 10 min of treatment at 37 degrees C.

Immunoreactive atrial natriuretic factor (IR-ANF) in human plasma.

A direct radioimmunoassay for ANF in human plasma was developed. A synthetic alpha-human atrial peptide (Ser 99-Tyr 126) was used for preparation of the iodinated tracer and the standards. The sensitivity of the method is 1.

Inhibition of pituitary adenylate cyclase by atrial natriuretic factor.

The effect of synthetic rat atrial natriuretic factor (ANF) on adenylate cyclase activity was studied in rat anterior and posterior pituitary homogenates. ANF (Arg 101-Tyr 126) inhibited adenylate cyclase activity in anterior and posterior pituitary homogenates in a concentration dependent manner. The maximum inhibitions observed were 42% in anterior pituitary with an apparent Ki of 10(-10) M, and 25% with an apparent Ki of 10(-11) M in posterior pituitary.

Changes of regional blood flow induced by atrial natriuretic factor (ANF) in conscious rats.

The effect of synthetic atrial natriuretic factor (ANF 101-126) has been studied on regional blood flow distribution. Microspheres (15 +/- 3 microns), labelled with either 113Sn or 57Co, were injected through an intraventricular cannula into conscious rats while a reference blood sample was withdrawn. Two minutes after the first microspheres injection either ANF or NaCl were injected.

Immunocytochemical localization of renin in juxtaglomerular cells.

The involvement of various organelles in the synthesis, transport, and packaging of renin in the juxtaglomerular cells of newborn mice has been investigated by immunocytochemistry with the protein A-gold technique. Highly specific rabbit antibodies against mouse submandibular renin were used. Mild fixation and embedding in glycol methacrylate allowed enough sensitivity to identify a steep gradient of labeling from rough endoplasmic reticulum to Golgi complex to secretory granules.

Inhibitory effect of atrial natriuretic factor on adenylate cyclase activity in adrenal cortical membranes.

The effect of rat synthetic atrial natriuretic factor (ANF) on adenylate cyclase activity was studied in adrenal cortical membranes. Synthetic ANF (Arg 101-Tyr 126) inhibited adenylate cyclase activity in a concentration-dependent manner. The maximum inhibition observed was about 25% with an apparent ki of 5 X 10(-11) to 10(-10) M.

Synthetic atrial natriuretic factor induces release (possibly receptor-mediated) of vasopressin from rat posterior pituitary.

The synthetic fragment (Arg 101-Tyr 126) of atrial natriuretic factor (ANF) induces release of arginine vasopressin from the isolated posterior lobe of the rat hypophysis in vitro. At a physiological concentration (3 X 10(-10)M) ANF was three times more effective than 61 mM KCL. In vitro binding studies with 125I-ANF revealed the presence of high affinity receptor sites displaying a pK = 9.

Structure-activity relationships of atrial natriuretic factor (ANF). II. Effect of chain-length modifications on vascular reactivity.

The effect of the length of ANF peptides on the inhibition of the norepinephrine-induced contraction was studied. Starting from the 26 residues ANF (Arg101-Tyr126), shorter N- and/or C-terminal fragments were produced, either by N-terminal chemical cleavage or C-terminal enzymatic digestion of ANF or both respectively. The N-terminal removal of Arg101 did not modify the inhibitory response.

Effects of chronic bromocriptine treatment of an estrone-induced, prolactin-secreting rat pituitary adenoma.

Bromocriptine (BROM), a dopamine (DA) agonist, is commonly and successfully used for long-term treatment of human prolactinomas. We have studied the effects of chronic BROM administration to female 344 Fisher/Lis rats bearing an estrone-induced, prolactin (PRL)-secreting pituitary tumor recently characterized as a model for human prolactinoma. The animals were injected twice daily with BROM (2.

Effect of chronic infusion of synthetic atrial natriuretic factor (ANF 8-33) in conscious two-kidney, one-clip hypertensive rats.

Conscious two-kidney, one-clip hypertensive rats were chronically infused during 7 days with synthetic ANF (8-33) (1 microgram/hr/rat) by means of osmotic minipumps. The initial blood pressure of 183 +/- 4 mmHg gradually decreased to 116 +/- 5 mmHg the last 2 days of infusion. Pressure diuresis returned to normal and pressure natriuresis was attenuated.

Radioautographic localization of 125I-atrial natriuretic factor (ANF) in rat tissues.

Rats were injected either with synthetic 125I-Arg 101-Tyr 126 atrial natriuretic factor (ANF) or with 125I-ANF together with an excess of cold Arg 101-Tyr 126 ANF. Binding sites in various tissues were accepted depending on two criteria: displacement of radioactivity by cold ANF and absence of localization of silver grains on putative target cells in the presence of cold ANF. Binding sites were localized on zona glomerulosa cells and on adrenergic and noradrenergic cells of adrenal medulla, on hepatocytes, on the base of mature epithelial cells of villi in the small intestine, on smooth muscle cells of the muscularis layer of the colon and on the base of epithelial cells of the ciliary bodies.