Regulation of secretion and clearance of C-type natriuretic peptide in the interaction of vascular endothelial cells and smooth muscle cells.
OBJECTIVE
To clarify the significance of C-type natriuretic peptide in the interaction between endothelial cells and vascular smooth muscle cells by investigating the endothelial production of C-type natriuretic peptide and the clearance mechanism of C-type natriuretic peptide using the endothelial cells-smooth muscle cells co-culture system.


RESULTS
Secretion of C-type natriuretic peptide in the direct co-culture of endothelial cells with smooth muscle cells elicited as much as a 60-fold increase compared with endothelial cells alone. The accumulation of intracellular cyclic GMP in the co-culture was consequently increased and the elevation of cyclic GMP level in the co-culture was abolished by the anti-C-type natriuretic peptide monoclonal antibody. The elevated cyclic GMP production in the co-culture was abolished by the anti-transforming growth factor-beta neutralizing antibody. Candoxatrilat (10(-6)-10(-4) mol/l), a neutral endopeptidase inhibitor, dose-dependently increased the concentrations of C-type natriuretic peptide in the culture medium with endothelial cells alone, but not in the endothelial cells-smooth muscle cells co-culture. The transcript of neutral endopeptidase messenger RNA was detected in endothelial cells but not in smooth muscle cells by reverse transcriptase polymerase chain reaction. Treatment with C-atrial natriuretic factor4-23 (10(-9)-10(-6) mol/l), the specific ligand for the clearance receptor of the natriuretic peptides, resulted in dose-dependent augmentation of C-type natriuretic peptide concentration and concomitant intracellular cyclic GMP production in the endothelial cells-smooth muscle cells co-culture but not in endothelial cells alone.


CONCLUSIONS
The present study demonstrated that direct interaction between endothelial cells and smooth muscle cells augments C-type natriuretic peptide secretion from endothelial cells through transforming growth factor-beta activation, and revealed that the enzymatic degradation is responsible for the steady state level of C-type natriuretic peptide in endothelial cells alone and that the receptor-mediated clearance mainly determines the augmented level of C-type natriuretic peptide in the interaction between endothelial cells and smooth muscle cells. The results taken together raise the possibility that endothelial C-type natriuretic peptide might play a role in regulation of vascular tone and remodelling.
Komatsu
Y
Y
Department of Medicine and Clinical Sciences, Kyoto University Graduate School of Medicine, Japan.
Itoh
H
H
Suga
S
S
Igaki
T
T
Ogawa
Y
Y
Kishimoto
I
I
Nakagawa
O
O
Yoshimasa
T
T
Nakao
K
K
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000378:metabolism*; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D018920:Coculture Techniques; D006152:Cyclic GMP / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006162:Guanylate Cyclase / Q000502:physiology; D008657:Metabolic Clearance Rate; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D020098:Natriuretic Peptide, C-Type; D015260:Neprilysin / Q000235:genetics; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D017461:Receptors, Atrial Natriuretic Factor / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology
D011506:Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D020098:Natriuretic Peptide, C-Type; D009320:Atrial Natriuretic Factor; D015260:Neprilysin; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C073616:atrial natriuretic factor receptor C; D006152:Cyclic GMP