The effect of adrenomedullin and proadrenomedullin N- terminal 20 peptide on angiotensin II induced vascular smooth muscle cell proliferation

Document Type: Original Article

Authors

1 Cadres Division One, The 401st Hospital of PLA, Qingdao 266071, China

2 Institute of Cardiovascular Research, Peking Medical University, First Hospital, Beijing 100083, China

Abstract

Objective(s): The study aimed to investigate the effects of adrenomedullin (ADM) and proadrenomedullin N- terminal 20 peptide (PAMP) on angiotensin II (AngII)-stimulated proliferation in vascular smooth muscle cells (VSMCs).
Materials and Methods: Thoracic aorta was obtained from Wistar rats and VSMCs were isolated from aorta tissues and then cultured. In vitro cultured VSMCs were stimulated with Ang II (10-8 mol/l) followed by various doses of PAMP or ADM (10-9, 10-8, or 10-7 mol/l). Cell proliferation as assessed by 3H-TdR incorporation. Protein kinase C (PKC) activity was measured by counting γ-32P radioactivity with liquid scintillation. In a separate cohort, in vitro cultured rat aortic vessels were treated with different doses of Ang II or PAMP (10-9, 10-8, or 10-7 mol/l). Cellular and secreted levels of PAMP, ADM and Ang II were measured using radioimmunoassay in the tissues and intubation mediums, respectively.
Results: Ang II (10-8 mol/l) treatment significantly increased both 3H-TdR incorporation and PKC activity in VSMCs (by 2.68 and 1.02-fold, respectively; both P<0.01 vs. the control). However, Ang II-induced elevation of 3H-TdR incorporation, and PKC activity was significantly inhibited by various doses of ADM and PAMP (all P<0.01 vs. the Ang II group). In rat aortic vascular tissues or intubation media, Ang II treatments stimulated the expression and secretion of PAMP and ADM in a dose-dependent manner, while PAMP treatments had no significant effects on Ang II levels.
Conclusion: ADM and PAMP inhibit Ang II-induced VSMCs proliferation. The interaction of Ang II, ADM and PAMP may regulate VSMCs and cardiovascular function.

Keywords


 

1. Nishikimi T, Kuwahara K, Nakagawa Y, Kangawa K, Nakao K. Adrenomedullin in cardiovascular diseases: a useful biomarker, its pathological roles and therapeutic application. Curr Protein Pept Sci 2013; 14:256-67.

2. Hirata Y, Takagi Y, Takata S, Fukuda Y, Yoshimi H, Fujita T. Calcitonin gene-related peptide receptor in cultured vascular smooth muscle and endothelial cells. Biochem Biophys Res Commun 1988; 151:1113-1121.

3. Haller H, Baur E, Quass P, Behrend M, Lindschau C, Distler A, et al. High glucose concentrations and protein kinase C isoforms in vascular smooth muscle cells. Kidney Int 1995; 47:1057-1067.

4. Shimosawa T, Fujita T. Hypotensive effect of a newly identified peptide, proadrenomedullin N-terminal 20 peptide. Hypertension 1996; 28:325-329.

5. Sugo S, Minamino N, Kangawa K, Miyamoto K, Kitamura K, Sakata J, et al. Endothelial cells actively synthesize and secrete adrenomedullin. Biochem Biophys Res Commun 1994; 201:1160-1166.

6. Eto T. A review of the biological properties and clinical implications of adrenomedullin and proadrenomedullin N-terminal 20 peptide (PAMP), hypotensive and vasodilating peptides. Peptides 2001; 22:1693-711.

7. Shimekake Y, Nagata K, Ohta S, Kambayashi Y, Teraoka H, Kitamura K, et al. Adrenomedullin stimulates two signal transduction pathways, cAMP accumulation and Ca2+ mobilization, in bovine aortic endothelial cells. J Biol Chem 1995; 270:4412-4417.

8. Takano K, Yamashita N, Fujita T. Proadrenomedu-llin NH2-terminal 20 peptide inhibits the voltage-gated Ca2+ channel current through a pertussis toxin-sensitive G protein in rat pheochromocytoma-derived PC 12 cells. J Clin Invest 1996; 98:14-17.

9. Inatsu H, Sakata J, Shimokubo T, Kitani M, Nishizono M, Washimine H, et al. Distribution and characterization of rat immunoreactive proadreno-medullin N-terminal 20 peptide (PAMP) and the augmented cardiac PAMP in spontaneously hypertensive rat. Biochem Mol Biol Int 1996; 38:365-372.

10. Sims C, Ashby K, Douglas JG. Angiotensin II-induced changes in guanine nucleotide binding and regulatory proteins. Hypertension 1992; 19:146-152.

11. Andreis PG, Markowska A, Champion HC, Mazzocchi G, Malendowicz LK, Nussdorfer GG. Adrenomedullin enhances cell proliferation and deoxyribonucleic acid synthesis in rat adrenal zona glomerulosa: receptor subtype involved and signaling mechanism. Endocrinology 2000; 141:2098-2104.

12. Goichberg P, Kalinkovich A, Borodovsky N, Tesio M, Petit I, Nagler A, et al. cAMP-induced PKCzeta activation increases functional CXCR4 expression on human CD34+ hematopoietic progenitors. Blood 2006; 107:870-879.

13. Hinson JP, Kapas S, Smith DM. Adrenomedullin, a multifunctional regulatory peptide. Endocr Rev 2000; 21:138-167.

14.  Rossi F, Bertone C, Petricca S, Santiemma V. Adrenomedullin antagonizes angiotensin II-stimulated proliferation of human aortic smooth muscle cells. Peptides 2006; 27:2935-41.

15. Hamid SA, Baxter GF. Adrenomedullin: regulator of systemic and cardiac homeostasis in acute myocardial infarction. Pharmacol Ther 2005; 105:95-112.