scholarly journals Steroidogenic effect of atrial natriuretic factor in isolated mouse Leydig cells is mediated by cyclic GMP

1986 ◽  
Vol 239 (2) ◽  
pp. 463-467 ◽  
Author(s):  
A K Mukhopadhyay ◽  
M Schumacher ◽  
F A Leidenberger
Keyword(s):  
Cyclic Gmp ◽  
Atrial Natriuretic Factor ◽  
Leydig Cells ◽  
Maximal Effect ◽  
Dependent Manner ◽  
Testosterone Production ◽  
Natriuretic Factor ◽  
Fold Stimulation ◽  
Stimulation Of ◽  
Atrial Natriuretic

The effects of different atrial natriuretic peptides on cyclic GMP formation and steroidogenesis have been studied in Percoll-purified mouse Leydig cells. Rat atrial peptides rANP (rat atrial natriuretic peptide), rAP-I (rat atriopeptin I) and rAP-II (rat atriopeptin II), in the presence of a phosphodiesterase inhibitor, stimulated cyclic GMP formation in a concentration-dependent manner. In the presence of saturating concentrations of the peptides, a 400-600 fold stimulation of cyclic GMP accumulation was observed. Among the peptides, rAP-II appeared to be the most potent. ED50 values (concentration causing half-maximal effect) for rAP-II, rANP and rAP-I were 1 × 10(-9) M, 2 × 10(-9) M and 2 × 10(-8) M respectively. A parallel stimulation of cyclic GMP formation and testosterone production by the cells was observed after incubation of the cells with various concentrations of rAP-II. In the presence of a saturating concentration of rAP-II (2 × 10(-8) M), maximum stimulation of intracellular cyclic GMP content was obtained within 5 min of incubation. Testosterone production by mouse Leydig cells could be stimulated by 8-bromo cyclic GMP in a concentration-related manner. At a 10 mM concentration of the cyclic nucleotide, steroidogenesis was stimulated to a similar extent as that obtained with a saturating concentration of human chorionic gonadotrophin (5 ng/ml). On the basis of these results we conclude that cyclic GMP acts as a second messenger in atrial-peptide-stimulated steroidogenesis in mouse Leydig cells. The steroidogenic effect of atrial peptides appears to be species-specific, since none of these peptides stimulated testosterone production by purified Leydig cells of rats, though in these cells a 40-60-fold stimulation of cyclic GMP formation in response to each of the three peptides was observed. However, 8-bromo cyclic GMP could stimulate testosterone production in rat Leydig cells. Therefore we conclude that the lack of steroidogenic response in rat Leydig cells to atrial-natriuretic-factor-stimulation results from an insufficient formation of cyclic GMP in these cells. This species difference would appear to result from a lower guanylate cyclase activity in rat Leydig cells.

Calcium and calmodulin regulate atrial natriuretic factor stimulation of cyclic GMP in a human renal cell line

Peptides ◽  
1991 ◽  
Vol 12 (5) ◽  
pp. 1127-1133 ◽  
Author(s):  
Michihito Sekiya ◽  
Jean Vaughn ◽  
Yuji Shigematsu ◽  
Edward D. Frohlich ◽  
Francis E. Cole
Keyword(s):  
Cell Line ◽  
Cyclic Gmp ◽  
Renal Cell ◽  
Atrial Natriuretic Factor ◽  
Natriuretic Factor ◽  
Renal Cell Line ◽  
Stimulation Of ◽  
Atrial Natriuretic

scholarly journals Kinetic analysis of internalization, recycling and redistribution of atrial natriuretic factor-receptor complex in cultured vascular smooth-muscle cells. Ligand-dependent receptor down-regulation

1992 ◽  
Vol 288 (1) ◽  
pp. 55-61 ◽  
Author(s):  
K N Pandey
Keyword(s):  
Smooth Muscle ◽  
Cell Surface ◽  
Atrial Natriuretic Factor ◽  
Dependent Manner ◽  
Receptor Complex ◽  
Down Regulation ◽  
Surface Receptors ◽  
Natriuretic Factor ◽  
Metabolic Degradation ◽  
Atrial Natriuretic

The kinetics of internalization, sequestration and metabolic degradation of atrial natriuretic factor (ANF)-receptor complex were studied in rat thoracic aortic smooth-muscle (RTASM) cells. These parameters were directly determined by measuring 125I-ANF binding to total, intracellular and cell-surface receptors. Pretreatment of cells with the lysosomotropic agent chloroquine and the energy depleter dinitrophenol led to an increase in the intracellular 125I-ANF radioactivity. After 60 min incubation at 37 degrees C, cell-associated 125I-ANF radioactivity fell rapidly in chloroquine-treated cells (> 85%) compared with the controls (< 45%). 125I-ANF radioactivity increased to a peak of 65% of the initial level within 15 min in chloroquine-treated cells compared with only 22% in the control cells. During the initial incubation period at 37 degrees C, chloroquine inhibited the release of both intact and degraded 125I-ANF in a time-dependent manner. However, at later incubation times, the effect of chloroquine was diminished and release of both degraded and intact ligand was resumed. Extracellular unlabelled ANF did not affect the release of degraded 125I-ANF but it accelerated the release of intact ANF by a retroendocytotic mechanism. After the endocytosis, about 30-40% of ANF receptors were restored to the cell surface from the internalized pool of receptors. The restoration was blocked by chloroquine or dinitrophenol but not by cycloheximide. Exposure of RTASM cells to unlabelled ANF resulted in a time- and concentration-dependent loss of ANF receptors. Unlabelled ANF (10 nM) induced a loss of more than 52% of 125I-ANF binding, and a complete loss occurred at micromolar concentrations. It is inferred that ANF-induced down-regulation of its receptor resulted primarily from an increased rate in internalization and metabolic degradation of ligand-receptor complex by receptor-mediated endocytotic mechanisms.

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