Aquaporin-2 water channels in spontaneously hypertensive rats.
Vasopressin (AVP), an antidiuretic hormone, is known to induce hypervolemia and to regulate the renal expression of aquaporin-2 (AQP2) water channels, but it is not yet known whether the latter are involved in the pathogenesis of essential hypertension. The aim of the present study was therefore to make a comparative study of blood pressure (BP), urinary volume (UV), urinary osmolarity (uOsm), urinary AQP2 (uAQP2), and plasma AVP levels (PAVP) in male spontaneously hypertensive rats (SHR; n = 30) at 3, 7, and 12 weeks of age and in male Wistar-Kyoto rats (WKY, n = 30), also after the subcutaneous administration of OPC-31260 (OPC), a human AVP V(2) receptor antagonist. At 3 weeks, SHR had markedly higher uOsm and lower UV levels than WKY. At 7 weeks, SHR were hypertensive, showing increased uAQP2, PAVP, and uOsm levels and a decreased UV. At 12 weeks, no significant changes were observed in this condition. At 7 and 12 weeks of age, OPC-treated WKY rats showed significant reduction in BP and uOsm and increase in UV with respect to untreated animals. From 3 weeks of age, OPC-treated SHR presented significantly lower BP levels, higher UV levels, and lower uOsm than untreated animals. In treated WKY and SHR, uAQP2 levels were lower than in untreated animals. The PAVP appeared to be higher in OPC-treated rats from both strains. These findings suggest that AVP and the AQP2 are involved in the pathogenesis of hypertension in SHR.
Buemi
Michele
M
Nephrology, Department of Internal Medicine, University of Messina, Messina, Italy. Buemim@Unime.it
Nostro
Lorena
L
Di Pasquale
Giuseppe
G
Cavallaro
Emanuela
E
Sturiale
Alessio
A
Floccari
Fulvio
F
Aloisi
Carmela
C
Ruello
Antonella
A
Calapai
Gioacchino
G
Corica
Francesco
F
Frisina
Nicola
N
D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D051399:Aquaporin 2 / Q000187:drug effects / Q000378:metabolism* / Q000652:urine; D020346:Aquaporins / Q000187:drug effects / Q000378:metabolism*; D001552:Benzazepines / Q000494:pharmacology; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001794:Blood Pressure / Q000187:drug effects; D004195:Disease Models, Animal; D006973:Hypertension / Q000209:etiology* / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014667:Vasopressins / Q000097:blood / Q000187:drug effects
D065092:Antidiuretic Hormone Receptor Antagonists; D051399:Aquaporin 2; D020346:Aquaporins; D001552:Benzazepines; D015415:Biomarkers; D014667:Vasopressins; C076251:mozavaptan