Masataka Majima (1), Keiichi Adachi (1), Takashi Ohno (1), Michiko Ogino (1), Maki Saito (1), Kazuyuki Kizuki (2), Osamu Katsumata (3), Shohei Yamashina (3) and Makoto Katori (1)
(1) Department of Pharmacology and (3) Department of Anatomy, Kitasato University School of Medicine, Kitasato 1-15-1 Sagamihara, Kanagawa 228, Japan (2) Department of Biochemistry, Faculty of Pharmaceutical Sciences, Science University of Tokyo, 12 Ichigaya-Funakawara-machi, Shinjuku-ku, Tokyo 143, Japan
Abstract: Urinary kallikrein excretion during oxytocin (OT) infusion were studied in anesthetized (sodium pentobarbital, 50 mg/kg, i.p.) young (4-weeks-old) spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY). OT-infusion (30 nmol/kg/30 min) to WKY significantly increased urinary excretion of the active kallikrein from the basal levels (25.4+-5.6 10-2 X AU/15 min, n=5) to 37.3+-5.0 10-2 X AU/15 min (P<0.05, n=5) and 50.7+-17.1 10-2 x AU/l5 min (P<0.05, n=5) 15 and 30 min after the start of OT-infusion, respectively. In SHR, OT-infusion did not increase the urinary excretion of active kallikrein, but did decrease the urine volume and sodium excretion. The concentration of the active kallikrein in the kidney of WKY was not changed by OT-infusion, but that of SHR was slightly increased. The OT-infusion resulted in significantly higher concentrations of the active kallikrein in SHR kidney than in WKY kidney. These results suggest that less excretion of urinary kallikrein in SHR during OT-infusion may be attributable to a lower response in the secretion of kallikrein from the kidney.
Keywords:
Renal kallikrein, Spontaneously hypertensive rat, Oxytocin, Diuresis, Natriuresis