Hemodynamic-independent anti-natriuretic effect of urotensin II in spontaneously hypertensive rats.
The present study aims to test the hypothesis that U-II might have a direct anti-natriuretic action in spontaneously hypertensive rats (SHR). Bolus U-II injection (15 nmol kg(-1)) caused a transient decrease in glomerular filtration rate (GFR), urine flow rate (UV), urinary sodium (UNaV) and potassium excretion (U(K)V) that corresponded with a committed decrease in mean arterial pressure (MAP) and renal blood flow (RBF) during the first 30 min. Continuous U-II infusion (0.2 nmol kg(-1)h(-1)) following a bolus U-II injection (0.3 nmol kg(-1)) caused an anti-natriuretic effect without any significant change in MAP, RBF, GFR, UV and UKV during the entire 1.5-h perfusion period in SHR. The levels of aldosterone and angiotensin II were not altered in the plasma and kidney, while plasma antidiuretic hormone decreased in response to U-II injection (15 nmol kg(-1)). Protein levels of U-II receptors (UT) were significantly increased in the kidney of 17-week-old SHR when compared with the age-matched WKY rats, while mRNA transcripts of both U-II and UT were increased in the kidney, left ventricle and thoracic aorta. In conclusion, U-II exerts a hemodynamic-independent anti-natriuretic action in adult SHR. The anti-natriuretic action of U-II in SHR is probably associated with an increased expression of the U-II-UT system in the kidney, suggesting a potential renal role of U-II in the pathogenesis of hypertension.
Shi
Ying
Y
Department of Physiology and Pathophysiology, Shanghai Medical College, Fudan University, 138 Yi Xue Yuan Road, Shanghai 200032, China.
Cao
Yin-Xiang
YX
Lu
Ning
N
Yao
Tai
T
Zhu
Yi-Chun
YC
D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D005919:Glomerular Filtration Rate / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D007668:Kidney / Q000098:blood supply / Q000502:physiology; D008297:Male; D009318:Natriuresis / Q000502:physiology*; D010446:Peptide Fragments / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012039:Regional Blood Flow; D012964:Sodium / Q000378:metabolism; D014579:Urotensins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D014655:Vascular Resistance / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000378:metabolism
D010446:Peptide Fragments; D011498:Protein Precursors; D014579:Urotensins; D014662:Vasoconstrictor Agents; C492079:urotensin II (4-11), Pen(5)-Trp(7)-Orn(8)-; D000804:Angiotensin II; C029677:urotensin II; D012964:Sodium