Korean J Nephrol.  2008 Sep;27(5):553-559.

Effects of Atrial Natriuretic Peptide on the Arterial Basal Tone in Renovascular Hypertensive Rats

• Choi S
• Kim MY
• Cho NS
• Sun JM
• Whi HW
• Jun JY
• Yoon PJ
• Chung JH
• Yeum CH

Abstract

PURPOSE: Hypertension may be involved an alteration of intrinsic basal tone in vascular smooth muscle. The purpose of this study was to investigate the vasorelaxant effect of atrial natriuretic peptide (ANP) on isolated non-contracted aorta from two-kidney, one clip (2K1C) renovascular hypertensive rats.
METHODS
2K1C hypertension was induced by clipping the left renal artery and were used 6 weeks later. Age-matched rats receiving a sham treatment, which served as controls. The thoracic aortae were mounted in tissue baths to measure the isometric tension.
RESULTS
ANP diminished basal tone in previously unstimulated thoracic aortic rings from 2K1C hypertensive rats, while it had no effect in the control rats. Endothelial destruction potentiated the vasorelaxant effect of ANP on basal tone in 2K1C rats. A similar potentiation of the ANP response was observed by pre-treatment with N omega-nitro-L-arginine methyl ester (L-NAME) or methylene blue in aortic rings with endothelium. Treatment with calcium-free Krebs decreased basal tone and abolished ANPresponse. These effects were observed only in aortic rings from 2K1C rats. Similarly, staurosporine and calphostin C, inhibitors of protein kinase C (PKC), lowered basal tone and abolished ANP-response in hypertensive rats.
CONCLUSION
These results demonstrate that ANP has a vasorelaxant effect on basal tone in 2K1C renovascular hypertension. Inhibition of ANP effects on basal tone by calcium-free Krebs and PKC antagonists suggests that altered Ca2+ -active tone is involved in hypertension, that modifies the response of vascular smooth muscle to the ANP.

Keyword

Atrial natriuretic peptide; Basal tone; Renovascular hypertension

MeSH Terms

Animals
Aorta
Aorta, Thoracic
Atrial Natriuretic Factor
Baths
Endothelium
Hypertension
Hypertension, Renovascular
Methylene Blue
Muscle, Smooth, Vascular
Naphthalenes
NG-Nitroarginine Methyl Ester
Placebos
Protein Kinase C
Rats
Renal Artery
Salicylamides
Staurosporine
Atrial Natriuretic Factor
Methylene Blue
NG-Nitroarginine Methyl Ester
Naphthalenes
Placebos
Protein Kinase C
Salicylamides
Staurosporine